Astronomers. In the wild.

News from the solar neighborhood

2011-07-25T03:36:00.003-05:00

The past week was a remarkable one for planetary science. Not only we had a probe arriving to an asteroid but also the solar family welcomed a new member.

In one side we have that the probe Dawn arrived to asteroid Vesta and is now in orbit around it. The story behind the whole mission is quite interesting. Actually the mission was cancelled many times and was only successful after the contractor (Orbital Sciences Corporation) offered to build the probe at cost. I certainly don't know of any other cases where the contractor ends up offering a whole probe at cost.

Vesta as seen from Dawn after it entered orbit.

The scientific program of this probe is quite ambitious. It plans to visit two of the biggest members of the asteroid belt, Vesta and Ceres, which were chosen as representative of "young" and "evolved" asteroids. Additionally, Vesta is (allegedly) the source of many of the micrometeorites that produce shooting stars in the sky which made it a particularly attractive target of study. This is also the first time a probe enters around the orbit of two objects. In previous "tours" like the Voyager missions the observations were made during flyby's. A similar option was considered a few years ago for Cassini with a potential transfer to Uranus which would had required a 20+ year cruise time. Eventually, that option was discarded and it was decided to send Cassini in a collision route with Saturn.

In a different development, it turns out that Pluto (the good old planet, now dwarf planet) system has at least three moons. This was spotted with the Hubble Space Telescope and the new satellite will be most likely studied by the probe New Horizons during its expected flyby of the system.

The Pluto system as shown by latest Hubble observations.

If you add all this with the results that are being announced from EPS-HEP there is no doubt that the past week has been one of the most exciting in a long time.

What is the relevance of the JWST?

2011-07-15T21:52:00.004-05:00

The James Web Space Telescope, the succesor of the Hubble Space Telescope is now under the very serious treat of termination due to budget cuts. The story goes like this: last week, the House Commerce, Justice, and Science Appropriations Subcommittee recommended the cancellation of the JWST project. This was followed when the full House Science, Space and Technology Committee approved the subcommittee's plan.

From a scientific standpoint this is a total disaster. We need the JWST if we are going to push the frontiers of current research to an epoch where the first stars and galaxies formed. The scientific case has already been well explained by Julianne Dalcanton in Cosmic Variance so I don't need to repeat it again.

But, from the point of view of the average Joe in the street, what is the justification for pouring truckloads of money in the JWST? Maybe the most poetic justification reads something like it will enhance our comprehension of the origin of cosmos and the existence of life in it. But nonetheless, I find that, while completely true, this kind of answers are easy to dodge by any opportunistic politician who wants to present himself as the "hero of the community" by "saving the hard earned money of the community from falling into this resources swamp".

Well, this is utter nonsense. Let me tell you why. The principal outcome of massive scientific collaborations is not a stream of papers with the latest and greatest results about fundamental questions but a stream of highly trained people who goes and contributes to the society in countless ways. I can not really estimate how many people went on to get a PhD based on Hubble's data or research started by Hubble's observation and while a few of them remain in the academia most have gone into all other corners of life. Many of them have joined big corporations or started their own corporation and contributed to the development of many technologies that are now commercialized and now create jobs for the people producing and manufacturing them. That is not to mention the secondary sources of income that are created when this people go and spend their income. So please keep in mind that by shooting down the JWST you are not only shooting down the few professional astronomers in your district but actually the training of some of the most skilled people in the society, the kind of people who will later produce some of the best sources of income available in society.

If you are in the USA, please take five minutes of your time and contact your representative to keep the JWST alive, the vote of the congress is still required to terminate this project.

If history can give us some clues as what can happen, let me mention the Superconducting Supercollider, the project that was supposed to lead experimental high energy in the late 20th and early 21st century. After its cancellation not only we as scientists remain with doubts about fundamental physics as the Higgs boson or superpartners but also the region of Texas where it was going to be built entered into a local recession and furthermore, now the advance of the field is led by the CERN in Europe, ending with decades of US dominance of the field. Please don't allow this to happen again.

Blog v3

2011-07-13T21:12:00.006-05:00

As anyone of you reading this has undoubtedly realized, the site has been completely overhauled. This is an attempt to bring it up to date in web standards. We now have an atom feed for updates, latex to mathml translation for maths and a new theme. You won't see it, but also the backend editor is new and is supposed to produce cleaner code. Let me know if you find any glitch with the new design.

On an unrelated thing. Neptune was discovered almost 165 years ago by John Galle who was looking for it after Adams and Le Verrier had predicted its existence based on the effect of Neptune on the orbit of Uranus. Since the orbital period of Neptune is 164.79 years we can say today that we are celebrating Neptune's first birthday!

Happy "birthday" Neptune!

Interestingly enough, from his observational notebooks we know now that Galileo had observed Neptune in his telescope which was too rudimentary to actually show its disc and reveal it as a planet. Additionally, in a strike of bad luck he just happened to observe Neptune when its proper motion was less noticeable. Nonetheless, there is some evidence that he was at least aware that it moved to respect the background stars. Unfortunately, bad weather prevented him to pursue this issue further. It is interesting how a small set of circumstances shapes history, not only of science.

Linux kernel 2.38 and Ubuntu Natty: The devourer of laptops

2011-07-12T11:24:00.016-05:00

Some of you have undoubtedly installed a Linux distribution featuring the kernel 2.38 (or a latter version). This kernel comes with Ubuntu 11.4 Natty Narwhal but also in Fedora 15 and some rolling release distributions like Arch or LMDE.

While installing a new fancy distro carries the advantage of bringing you with the latest packages including the new fool-proof desktop environments that have been recently in the spotlight (unity and gnome 3) it will also bring you to one of the most annoying bugs that I have dealt with.

All the Linux kernel versions starting with 2.38 made changes to the Active-State Power Management (ASPM) that have resulted in a dramatic power consumption increase. This might be not so evident for a desktop computer but can easily trounce the charge duration of a laptop by a third, not to mention the fact that it turns it into a portable pan.

To fix this we need to enable the pcie_aspm=force option. The downside is that this might turn some systems unstable or even prevent them from booting. Use this at your own risk.

A simple way to see if this fix will work for your recently turned into pan laptop is to enable this option for a single boot. In Ubuntu you need to select your Ubuntu system and press e in the menu that allows you to choose an operating system just after turning on your computer. This allows you to edit the boot options for this session. Locate something looking like quiet splash and add pcie_aspm=force inmediately next to it, separated by a space. If your computer boots and remains stable you will notice that it will heat considerably less and that battery life is extended.

Now, to make this change permanent we need to edit the bootloader. Open a terminal and enter:

gksu gedit /etc/default/grub

which will ask you for privileges escalation (the password of the administrator). Then, look for this line

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

and change it to

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash pcie_aspm=force"

Make sure that this is indeed how the line looks like, we don't want to screw the bootup. After that we need to update the bootloader:

sudo update-grub

And that's it, you have rescued your laptop from becoming your next broiler. Just reboot and the change must be there permanently.

From the quantum world to the guy next door (part 1)

2010-11-23T02:25:00.021-06:00

This post will be a little more technical than the usual ones. Nonetheless, I believe there ia "market" for it: students who are just learning quantum mechanics and might require to dispel much of the baloney that is told about the quantum weirdness. Recently I was discussing with one of the cobloggers of astronomers in the wild about some limerick from David Morin's mechanics book:

When walking, I know that my aim
Is caused by the ghosts with my name.
And although I don't see
Where they walk next to me,
I know they're all there, just the same.

This is mentioned just as some side note when discussing the stationary action principle, specifically, in the context of learning if there is a deep reason behind it. The stationary action principle says that the quantity S, called the action and given by

\[ S= \int_{t_a}^{t_b} dt\ L(x,\dot{x};t) \]

should take a stationary value. That means that from all possible paths involved in getting from a to b, a classical particle will take the path in which the action takes a minimum value (well, actually a stationary one, usually the minimum). This is the principle behind classical mechanics. The motion of everything we can see around us, including the stars in the sky or matter around a black hole follow from this principle.

Hence, it would be great to know if there is a reason behind this principle. Well, yes, there is. It is deeply rooted in quantum mechanics and its essence is captured in above's limerick.

So, the purpose of the few next posts will be to see how we can pass from the quantum description of the world to the kind of phenomena we observe everyday when dealing with baseballs, pulleys and all that.

This is not a trivial question, every experiment has confirmed the validity of quantum mechanics as the correct description of our world but it is in stark contrast with the intuition we have all developed from observing microscopical objects all our life. Nonetheless, at first glance, both descriptions are radically different. To see how weird the quantum behavior is for us, macroscopic beings, let's consider one situation that shows most of the quantum subtleties: the double slit experiment.

Consider some particles source S, placed at a point A. In front of it, we place a screen C with two slits in it. Hence, we expect that any particle arriving to a screen at the point B where the arrival of electrons is measured must pass through one of the slits. This configurations is shown below.

Well, if we do this experiment with marbles, baseballs, grains of sand or any other classical object coming out of the source S, then the outcome will be just what we expect. Namely, if we shut one of the slits, then the distribution of arriving marbles at B will be peak just in front of the open slit. The resulting distribution of arriving marbles at B when both slits are open is just a sum of the peaks produced by the particles entering through each slit. This is shown below.

Here, the outcome of the double slit experiment with classical particles is shown. If we shut one slit, we get one sharp distribution (shown in blue). The outcome with both slits open is just the sum of the two peaks and it is shown in red.

There is a second classical object that we can throw against our screen at C: waves. So, lets imagine that we place the whole setup in a pool and the source at A stirs the water a little bit so it create waves. In a realist experiment, we should place S very far from C so we can have some nice plane waves arriving at C, but ignore such nuances for our purposes. When the incoming wave arrives to C, each slit will act as a new wavefront and produce an outgoing wave. Since we have two slits, the outgoing waves will be out of phase from some parts and in phase for others. This is better seen in the picture below.

The darker zones correspond to places where destructive interference happens, namely where the waves are completely out of phase and cancel out. On the other hand, clear zones are where waves are in phase and constructive interference happens. The outcome of all this, is that the distribution at B will be different from the one we got using marbles as we now have some interference pattern, as shown below.

As you can see, we now have many peaks and actually the biggest one is in front of a closed part of the screen C ! This is just the result of the way waves behave: they can add or subtract from each other in stark contrast with marbles as we do not expect one marble to cancel another!

So, if an electron behaves exactly as a marble we expect that the chance of arrival at some point x of the target B will obey two simple rules:

Each electron which passes from the source S to some point x in B should go through either hole 1 or 2.
The chance of arrival to x is the sum of two parts: P1 the chance of arrival coming through hole 1, plus P2; the chance of arriving after coming through hole 2.

I repeat, this is the case for classical particles. Even in classical mechanics we can get a different behavior by using waves, as illustrated above. Now, we use to imagine electrons as lil' charged things and with a big degree of naivety we would expect these two rules to extend to electrons.

Well, what happens when we use electrons? It turns out that we get a distribution identical to the one we get from waves! This is a good place to stop today, but nonetheless I should tease you a little.

The questions that arise immediately are: is the electron a wave? If so, how can we reconcile that with our intuition that it should pass through one hole? how can we measure that? As of now, we could actually say that the electron is indeed a wave. Nonetheless, that contradicts our experience of electric charge as a flow of electrons, which has proved to be extremely successful. Additionally, when using electrons to strip electrons from some metal the behavior is consistent with particles (its analog with photons is the well known photoelectric effect). Actually, all the subsequent discussion for the quantum case can be carried as well with photons. This kind of behavior with electrons behaving as confused teens not making their mind about being particles or waves is usually stated as the wave/particle duality. Hopefully, by the end of this series of posts you will agree with me that such duality is a rather childish way to describe things: electrons are particles, which get their peculiar behavior due to the way probabilities/amplitudes add. Furthermore, the mechanism to get the amplitude will lead us directly to the classical world with which we are all so familiar.

Besides, now that we can not use the two rules stated above, what rules should we use to calculate the distribution at B? This last question is essential: the big difference between the classical and quantum world is in the way we calculate probabilities. That is the topic for the next post. Meanwhile, you can read what happened when this experiment was performed in 1998 by E. Buks et al.

For all you able to read spanish, I decided to continue this "story" in my spanish website: sinédoque. This was due to the capabilities of blogger which were too meager at the time, specially regarding mathematical expressions. I have just implemented a new system on this blog so maybe some more "math heavy" posts will appear here in the future. Keep tuned.

The Towers of Hanoi

2010-02-15T09:56:00.007-06:00

I don't know why but I recently came back to this old, interesting little problem. For those not familiar with the puzzle, here's an excerpt from Wikipedia:

[The Towers of Hanoi puzzle] consist of three rods, and a number of disks of different sizes which can slide onto any rod. The puzzle starts with the disks in a neat stack in ascending order of size on one rod, the smallest at the top, thus making a conical shape.
The objective of the puzzle is to move the entire stack to another rod, obeying the following rules:

Only one disk may be moved at a time.
Each move consists of taking the upper disk from one of the rods and sliding it onto another rod, on top of the other disks that may already be present on that rod.
No disk may be placed on top of a smaller disk.

Here's an image of how the initial configuration looks like with 8 disks (also from Wikipedia):

Also, here's an applet of the puzzle so you can try to solve it yourself: MazeWorks - Tower of Hanoi. Try with 3, 4 and maybe 5 disks, and see if you can solve it with the fewest number of moves.

You'll notice that, according to that applet, the minimum number of moves for the puzzle with N disks seems to be 2^N-1. The other day it occurred to me that this can be proven by mathematical induction easily, and that the procedure for doing so is actually the recipe for a recursive algorithm to solve the problem. I'll talk about these two items separately.

Proof that it takes 2^N-1 moves to solve the puzzle.

We want to prove that a solution to the Towers of Hanoi problem requires 2^N-1 moves, where N>=1 is the number of disks to move. Let's proceed by mathematical induction.

1) Base case: we prove the claim is valid for N=1.

If there is one only disk, moving it to the correct peg requires (trivially) a single move. And 2^1 - 1 = 1, which show what we want to prove is true for the base case.

2) Induction Hypothesis: we assume the claim is valid for N=k, where k >= 1 is some number.

This assumes that the solution to the k-disk problem takes 2^k - 1 moves. That is, we assume it takes 2^k - 1 moves to transfer k disks from one peg to an empty peg, using a third empty peg as auxiliary. Note that because of the rules, an "empty peg" is equivalent to "a peg containing one or more disks that are all larger than the disks we're moving".

3) Prove the claim holds for (k+1) disks: we must show that if the induction hypothesis is true, then we can prove that the claim is true for the (k+1)-disk problem as well.

In other words, we want to show that if it's true that the k-disk problem requires 2^k-1 moves to solve, then the (k+1)-disk problem requires 2^(k+1)-1 moves to solve.

So we want to solve the (k+1)-disk problem. Let's call the peg on which the disks initially reside the S (source) peg, the peg to which we want to transfer all the disks the D (destination) peg, and the third peg the I (intermediary) peg, which we'll use as auxiliary peg during the process. Then, we proceed as follows:

Move the upper k disks from the S peg to the I peg. This is possible since we assumed it in the induction hypothesis, which also establishes doing so takes 2^k - 1 moves. This leaves the largest disk alone on the S peg.
Now that it's possible, move the largest disk from the S peg to the D peg. The disk is now in its final position, so we don't have to move it again. This takes 1 move.
Move the k disks that were on the I peg to the D peg. Again, by induction hypothesis, this takes 2^k - 1 moves. It doesn't matter we're moving the disks to a non-empty peg, since the disk on the D peg is larger than any disk we're moving, and hence doesn't interfere with the task. The S peg is used as auxiliary peg in this process. After this, the problem is solved, for all disks lie on the D peg.

So what was the total move count? In step i), we used 2^k-1 moves, in step ii) a single move, and in step iii) 2^k-1 moves again. The total:

Moves = (2^k-1) + (1) + (2^k-1) = 2*(2^k) + (1-1-1) = 2^(k+1) - 1

And so, we have proved that if it takes 2^k-1 moves to solve the k-disk problem, then it takes 2^(k+1)-1 moves to solve the (k+1)-disk problem. This, together with the base case whose validity we verified in the first step, makes the claim valid for all N. Q.E.D.

Optimality

Note, however, that at first this proof does not guarantee this is the optimal number of moves needed to solve the problem, only that the N-disk problem can be solved with 2^N-1 moves. Luckily, it seems I can justify the optimality of the solution formally.

Consider the following modified proposition, which we'll prove by induction too: "It takes 2^N-1 moves to solve the N-disk problem, and this is the minimum number of moves of any solution". This is trivially true for the base case (N=1).

To prove the induction step, consider the following argument. We want to show that solving the (k+1)-disk problem requires a minimum of 2^(k+1)-1 moves.

But consider that no matter how you solve the problem, at one point you'll need to move the largest disk to the D peg. Since the largest disk cannot be placed on top of any other disk, this means that the remaining k disks must be on the I peg when this happens. There is no other way this could be. So any solution strategy, no matter what is is, must pass through this common state.

Now, by the (modified) induction hypothesis, moving k disks from one peg to another is done optimally in 2^k-1 moves. So putting the puzzle in the configuration required to move the largest disk to the D peg requires a minimum of 2^k-1 steps. Similarly, after the largest disk is moved to the D peg, transferring the remaining k disks to the D peg also requires a minimum of 2^k-1 steps.

Finally, the middle step, moving the largest disk to the D peg, is trivially optimal, since we're moving a single disk.

With this, we prove that if the solution of the k-disk problem requires a minimum of 2^k-1 moves, then the solution of the (k+1)-disk problem requires 2^(k+1)-1 moves, and that it is also the minimum number of moves.

The uniqueness of the optimal solution is also proved with the same argument, since moving a single disk (both in the base case and in moving the largest disk to the D peg) is both optimal and the unique way to do it.

Solution Algorithm

A nice thing of this proof by induction is that it naturally produces a recursive solution algorithm. Basically, we define a function, let's it call it Solve(n, A, B, C), that moves n disks from peg A to peg C, using peg B as intermediary. The function is defined recursively following the logic of the proof above (Python pseudocode):

 def Solve(n, A, B, C):
  if (n==1):
    A.transferTo(C)
  else:
    Solve(n-1, A, C, B)
    A.transferTo(C)
    Solve(n-1, B, A, C)

This is almost full Python code; it's only missing the data structure definitions needed to handle the disks and pegs. But it shows the heart of the algorithm. Note how the function calls itself recursively twice: first in a series needed to move the (n-1) disks to the intermediate peg, then in a second series to move the (n-1) disks onto the final peg. In each call, the peg order is changed to reflect which pegs are source, destination and intermediate.

You can get the full Python code here.

LHC alarmism debunked

2010-01-11T10:01:00.004-06:00

I just attended a seminar by Michelangelo Mangano titled "Black holes at the LHC: safety and society". While of course the bottom line was that there is no real risk of the LHC destroying the universe it is still worthwhile to discuss it a little bit.

So, a little compendium of why you shouldn't be scared of LHC produced black holes:

LHC is almost surely not likely to produce black holes, simple as that, most of the models predicting such scenarios work with additional dimensions and require a higher center of mass energy than would be available at LHC. Anyway, there are indeed some scenarios where black holes can indeed produced at LHC, they are not very plausible but a case can be surely made from them.
Black holes are unstable: Black holes decay via Hawking radiation. Particles can be created out of "nowhere" in the vacuum, a rather sloppy argument essentially says that the uncertainty principle allows particles to pop out of nowhere as long as the energy loan required to create them is payed really fast. Now, consider one of this virtual particles being created just outside the black hole and the other one just inside of the black hole. The net effect for an observer outside the black hole is that black hole is radiating, in the process the black hole is loosing mass that is just escaping in this radiation. This radiation is not only electromagnetic, in principle a black hole can radiate anything.
This makes the black hole to "evaporate" as it looses mass via radiation, it turns out that the lifetime of a black hole is proportional to its mass. For black holes with really small mass, like the ones speculated to be produced at LHC this yields out such a short lifetime that there is not a reason to worry at all.
We can now be cynical and say that QFT in curved spacetime (the fancy name for the framework used to calculate this kind of things) is not really experimentally established, maybe there is something wrong with it and black holes could be stable, then you should consider that...
Black holes produced in particle collisions are charged: Collisions at hadron colliders happen between the charged components of protons and conservation of charge requires that the final product (in this case a black hole) remains charged. Any charged particle, even a microscopic black hole interacts with matter in a way that has being throughly studied and is summarized in the so called Bethe-Bloch equation for the range of energies likely involved in the LHC. The result is that the black hole will just radiate all its energy away in a short distance. But hey, what if we are somehow missing something in the creation of microscopic black holes and it is possible to produce stable and neutral black holes? This looks extremely unlikely but lets go ahead and see what can happen if they are indeed produced.
Accretion rates from microscopic black holes are negligible: Lets say we have a slow moving, stable and neutral black hole. Can it eat the Earth and cause all other kinds of havoc? Well, if we model mass infall into a black hole via Bondi accretion (a fancy name for spherical accretion) it turns out that to gain a considerable mass, say 1 ton, a huge amount of time is required. Right now I don't remember now the exact number but it was of the order of a thousand millions of years. If a predator capable of running at most a 1mm per year is chasing you with bad intentions you wouldn't be scared, would you?

Well, despite this arguments there is still people around trying to halt LHC and the issue has even been brought to court, where it has always been dismissed based on technicalities, mostly because the LHC is out of jurisdiction of the court.

So, why I am telling you all this? Well, wait for tomorrow...

Create wallpaper slideshow in Ubuntu 9.10

2010-01-01T11:19:00.012-06:00

First of all, happy new year! Nothing like the morning of a new year to be messing around with Linux and Python!

One of the new things in Ubuntu 9.10 is that you can now use a wallpaper slideshow for your desktop, which will cycle your desktop wallpaper at regular intervals from a selected pool of wallpapers. The default Ubuntu 9.10 comes with a space-themed wallpaper slideshow, but there is apparently no option to create your own ones. However, the configuration is stored in plaintext XML files, one in /usr/share/gnome-background-properties and the other in the corresponding directory where the images are stored, in /usr/share/backgrounds.

The following Python script will automatically create these two XML files so that you can set a wallpaper slideshow with the images of your preferences.

Slideshow Builder script
(Right-click and select "Save Link As..", or the equivalent in your browser).

Here's the instructions. You will need root access since the directory where you're doing the operations, /usr/share/, is owned by root. Simply use sudo (or sudo -i if you're lazy).

1) Create a directory in /usr/share/backgrounds with the name of your slideshow. For instance, if the desired name is 'space', the dir should be called '/usr/share/backgrounds/space/'.

2) Copy all the wallpaper images to that folder. The supported formats are jpg, png, gif and bmp.

3) Run the Python script in the images directory. This will automatically create two xml files: one in the (current) images directory, and another one in /usr/share/gnome-background-properties.

4) That's all! You can now select the slideshow in the Gnome wallpaper selection interface.

A sample usage of the script is shown in the following image:

And the slideshow now appears in the desktop Background selection screen:

Update: I've fixed the dead link to the script.

No dark matter, yet...

2009-12-18T06:44:00.003-06:00

So, what happened with all this CDMS fuzz? The collaboration reports 3 events out of a expected background of 0.5. Nonetheless, one of the events was out of the "box", so lets forget about it. So, with 2 events we have a 1.06 sigma signal and with 3 events we have a 1.7 sigma signal.

It is just a ridiculously low signal, and by no means can be considered a discover. Nonetheless, it is rather interesting and intriguing. Experiments using liquid targets have a significantly bigger mass and can catch up this signal in one, maybe two years to a level where it can actually be considered a detection, but, until then, the coin is still in the air regarding dark matter.

CDMS results in a few hours!

2009-12-17T13:36:00.002-06:00

As most of you know, there is a rumor about CDMS getting some of sort of signal from its dark matter search. Well, in a few hours we will know if all the fuzz around it was justified.

CDMS stands for cryogenic dark matter search. It is a solid state detector designed to "listen" the sound made by dark matter particles when they interact with the nucleus of the atoms in the detector. These interactions cause the nucleus to recoil, as a result of that the atoms in the detector (which are arranged in a lattice) vibrate and produce phonons (some sort of quanta of sound). This signal can be measured and used to detect the interactions of weak interacting particles.

Now, this is only a very simplified description of the experiment. The practical difficulties are huge. First of all, random thermal vibrations can wash away very easily any signal, so the detector must be kept at really low temperatures. Then, collisions with cosmic rays will also spark the detector as fireworks, for this reason the detector is located underground in a deep mine in Minessota. But, how about other "backgrounds" like nuclear decay of particles in the rocks surrounding the detector? Well, the study of systematic backgrounds is really an art. One way to calibrate the detector is to place it close to some radioactive source and use the signal gathered this way to callibrate the detector.

Early in the year, I saw the results of the CDMS collaboration and there was no signal (or hint of it), so it is hard to think that the results that are about to be announced will have 5-sigma signal (the usual threshold accepted as a detection), but maybe they got some sort of provocative signal at a smaller sigma level. Or maybe all the fuzz was just that, fuzz.

Anyway, we will know the answer in a few hours!

Fixing unrecognized File Type extensions in Ubuntu

2009-09-23T08:53:00.007-05:00

I've had a little 'bug' in my Ubuntu for the past month that was annoying me a bit. I use TeXmacs for creating/editing small LaTeX documents. The problem is that Nautilus was incorrectly detecting the file type of .tm files, thinking they were plain text documents (see image below). The consequence is that TeXmacs files would be opened in gedit (or the default text editor) when opening them through the Nautilus file browser.

The first solution attempt was right-clicking a .tm file, going to "Properties -> Open With" and changing the default application to GNU TeXmacs. This was a disaster, since now *all* plain text files would be opened in GNU TeXmacs, since Nautilus genuinely believed a .tm to be the same as a .txt and thus changed the default application for all text files.

My second attempt at a solution (after googling a bit) was checking the MIME file type associations, which is the way Ubuntu associates an extension to a file type. The info is all in the file /etc/mime.types. However, to my disappointment, this file already contained a mime type for TeXmacs documents, indicated by the entry
"text/texmacs tm ts". So even though the mime type was correctly recognized, it seems Nautilus wasn't picking it up. This could be further deduced from the fact that running the command file on a .tm document in the terminal returned the correct mime type.

After more googling, I finally discovered that this is in fact a bug and found a fix for it:

http://savannah.gnu.org/bugs/?25938#discussion

Essentially, you manually create an xml file describing the TeXmacs mime type to /usr/share/mime/packages and then manually update the mime database of the system (setting an icon for the file type is optional, but may be useful).

NOTE: the original poster of the above bug fix made a small typo: an extra semicolon (;) at the end of the line containing "mime-info xmlns=" Remove it before trying to update the mime database.

After this is done, logout / re-log (or simply kill / restart nautilus from the terminal) and the new file extension should now be recognized:

The nice thing about this is that it should conceivably work for any other file type that has a correct mime type in /etc/mime.types but is not being recognized by Nautilus.

Hope this was helpful ;).

Goodbye MP3s!

2009-09-18T10:04:00.004-05:00

The story - skip to the end if you only want the scripts and could spare my self-righteous opinion.

I've used MP3 as my music compression format for years, as I'm sure most people have, without thinking too much about it. But my relatively recent ascension into Free Software has changed my perspective on many things related to software. Especially, it has given me the awareness that, in general, as a user I am the one in charge and I have the power to choose what I want to use and how I use it - or at least I should.

MP3 entered the equation when I learned that Apple iPods do not play any other music format except WAV, MP3 and ACC related codecs (such as M4A). The reason for this is simple: these are patented, proprietary compression formats that Apple supports in order to introduce DRM (copy protection), using iTunes as a centralizing vehicle. While I can't deny their right to do so, I do believe this sort of policies go against the realization I exposed in the previous paragraph.

I don't own an iPod. I have this small, very practical, albeit ugly, 2GB iBit music player that I bought at Sam's Club for under $80 that will play MP3, M4A, FLAC, OGG and pretty much any format I've thrown at it. Why would this small company support OGG while Apple does not? Would Apple lose business if they did?

So, exercising my right of decision, I've abandoned the MP3 format in favor of free alternatives: OGG for standard music compression and FLAC if I ever need lossless compression. Converting all my music to OGG is no easy task, however, mainly due to the size of my music collection. In Windows, I'd probably have to find a small utility that can do the batch conversion, and it probably would cost me something.

Fortunately, Linux is rooted at the most fundamental level on the basic premise that the power belongs to the user (as opposed to Apple's diametrically opposed mindset), and it provides countless tools that allow you to perform complex tasks with a minimum effort. So I took this as an opportunity to learn a bit about bash scripting and wrote a small script to handle the conversion for me.

The script

Here's the link to the source code. Copy/paste to your favorite text editor, save and set execute permission (chmod +x mpeg2ogg.sh).

mpeg2ogg.sh

The script assumes you have two programs installed in your system: mpg321 and oggenc. The former handles MP3 decoding and the latter compression to OGG. If you don't have them, you can most certainly get them through your favorite package manager (in Debian/Ubuntu, all you need to do is a sudo apt-get install mpg321 vorbis-tools).

Using the script is simple. Navigate to the root directory of your music library (in my case this was /home/meithan/Music), copy the script there (or put it in a dir in your path), and run it . It will find all MP3s in the directory tree rooted in the current directory, and convert them all to OGG. The script builds a list of all the files that it finds and uses it as a queue: every time a file is converted, it removes that entry from the list. Thus, you can stop the script whenever you want, and just run it again at a later time and it will resume where it had stopped (reading from the file list.txt).

A note: since I still don't trust my bashing abilities enough, the script won't delete your original MP3 files. You should first try the OGG files first, and then, if you're confident the conversion was successful, manually delete your old MP3s. Now, since "manually" means something completely different in Linux, here's a minimal script that will batch remove all MP3s in the current directory and its subdirectories:

mp3del.sh

Hope my ranting and/or bash hacking are useful to someone.

Coolest fish ever

2009-02-25T11:21:00.004-06:00

The world is full of surprises and this amazing fish is certainly one of them. This 6 inch wonder is called Macropinna microstoma and features a transparent head!

The fish, discovered alive in the deep water off California's central coast by the Monterey Bay Aquarium Research Institute (MBARI), is the first specimen of its kind to be found with its soft transparent dome intact.

Now, that small orifices in the front of the fish are not its eyes but a smelling organ. The barrel eyes are inside the green barrels and can be rotated inside the transparent head, giving this fish a quite wide visual range.

The barreleye lives about 2000 feet under the surface, where it just stays floating with the eyes looking upward, when a prey arrives they usually have to steal it from siphonophores (jellies that can grow to more than 33 feet). To make this feat it rotate its eyes and goes straight for its prey! Quite amazing.

The universe, yours to discover

2009-02-09T20:22:00.002-06:00

As probably all of you know by now, 2009 is the "year of astronomy", a sort of celebration of the 400th anniversary of the first astronomical observations using a telescope by Galileo (of course it is arguable if he was the first to do it, nevermind).

Of course this blog will join this, so you may expect more posts here, it has been rather complicated posting to this site, it is always hard to grab some time specially since many posts that are intended to be just "quick posts" end up consuming a significant amount of time. It also seems to me that you can do lots of nice posts that will be quickly erased of everyones mind but you are always dangerously close to make some comment that might annoy someone, of course that will change when I get tenure!

Anyway, lets see how this year unfolds!

Summer time

2008-06-22T21:24:00.003-05:00

The semester has ended and it's time for the summer adventures, certainly this summer promises to be loaded of adventure for me. Hopefully the posting frequency will increase, which is quite a good thing as this blog has been rather inactive lately.

Right now I have just arrived to CRyA (Center for radioastronomy and astrophysics) to continue a collaboration on hypercompact HII regions (this regions are where massive star formation takes place, more on that on a some near post). The cab driver as soon as he heard I was an astrophysicist (student, of course) instantly replied: "but that's just an awful lot of f.....n maths", and proceeded to tell me the stories of "all those crazy geniuses" like Dali, Einstein, Newton and that "nut economist" (don't ask me who that nut economist is), at the end of the trip I guess he had the impression that he thought I'm every bit as crazy as them (but way dumber than them), which is fine, at least I'm in good company.

Join the PAM!

2008-04-21T22:27:00.008-05:00

There is a nice project started by Julien Girard called wikiPAM, the idea behind this project is creating a wiki for the mexican astronomical community (the name comes from Proyectos Astronómicos Mexicanos, or Mexican Astronomical Projects). Anyone doing any sort of research in astronomy with a mexican group can get an account there and post their work.

This portal has a lot of potential, you can post your code (or modifications to it), your data, an announcement for your future projects... It seems to me like a wonderful tool for a grad student looking for a thesis project.

As far as I know it is possible to post there information only accessible to people in the same research group, so you can also use it to share confidential information to the rest of your group without anyone else seeing the data before it is made public.

There is also a portal for astronomical societies (i.e. amateur astronomers) in Mexico, it is called Cosmowiki. If you can read spanish look at this interesting account of the first mexican connection to internet that I found at cosmowiki, clearly showing its potential for outreach.

I conclude this small post inviting you to join this nice idea, you "only" need to be involved in research that somehow has the participation of the mexican astronomical community in it (for example having mexican astronomers in your group, or using mexican instrumentation like the LMT).

National astronomy meeting

2008-04-14T20:22:00.002-05:00

Tomorrow starts the national astronomy meeting, this is the only event of the year when all the astronomical community meets in a single place and it's also a great occasion for seeing old friends from other institutions. I'll be participating with some of my work in regions of massive star formation.

Hopefully I'll be posting soon about the interesting stuff that emerges there.

A new kind of supernova

2008-03-01T19:34:00.009-06:00

We are sure that at least two kinds of astrophysical black holes exist, one kind correspond to black holes of stellar mass (around 8 times the mass of the sun or bigger) and the black holes at the centers of galaxies with millions of solar masses. For some time there was speculation about the existence of some intermediate mass black holes with masses around few thousands the mass of the Sun, evidence from the rotation of stars in globular clusters gave the first evidence for the existence of intermediate mass black holes.

Despite evidence from the rotation of stars around the centers of globular clusters, the case is far from closed, the centers of globular clusters are regions of high density, filled with degenerate stars (mostly white dwarves) and maybe the rotation speeds can be explained by an overabundance of stars. A new paper (available here) by Stephan Rosswog, Enrico Ramirez-Ruiz, and William R. Hix proposes a radically new method for searching this black holes.

In close binary systems composed by a red giant and a white dwarf, the white dwarf can steal some matter from the red giant star (which has a low surface gravity), matter falling into the white dwarf has angular momentum and as a result of that an accretion disk is formed, white dwarves are supported against gravitational collapse by electron degeneracy (essentially if you try to pack electrons too closely they will start to move faster as a consequence of the uncertainty principle), this degeneracy can only support a mass of about 1.4 solar masses (otherwise the electrons would move faster than light), this is known as the Chandrasekhar limit, so when the white dwarf has "stealed" enough mass from its companion it will eventually surpass this limit, in this case the star is reignited by a mechanism known as carbon deflagration, creating a supernova explosion of the IA type.

Now, enter intermediate mass black holes. Computer simulations including gravity, hydrodynamics and nuclear physics show the effects of a close interaction between a white dwarf and an intermediate mass black holes. The star is heavily disrupted by tidal effects and acquires a pancake-like form, as the star is squeezed there is a dramatic increase in pressure and the star is reignited and creates a new kind of supernova, around half of the mass is ejected and the other half falls into the black hole creating an accretion disk that should emit x-rays.

This image shows the interaction of a white dwarf and a black hole, the star is heavily deformed in the first two frame, in the intermediate frames the star reignites and explodes, the "bubble" is the ejected material and at the bottom left corner an accretion disk is formed, the last two frames follow the evolution of this disk.

While this supernovas should be much scarcer than usual IA supernovas, new surveys like the LSST should detect enough supernovae to have a good chance of detecting this events, and x-ray emission should be detectable by the Chandra Space Telescope. The light curve should be different, although I haven't seen any detailed model. Considering that globular clusters are composed mostly of old stars and large populations of white dwarves this events should be happening relatively frequently around the universe and might give us unequivocal evidence of intermediate mass black holes.

Back to classes

2008-02-17T18:07:00.004-06:00

This weeks have been a bit hectic, the new semester has started and I have been busy handling endless tasks (which is why I haven't posted much in these days).

This semester I will lecture for half of the general astronomy course, mostly about celestial mechanics (Keppler's laws, tides, Roche lobe and Lagrange points) and some practical optics (mostly the types of telescopes and the effect of diffraction on a telescope's resolution). The later half of the course is about stars and galaxies but I won't be lucky enough to lecture about that.

This seems to be a good place to hear your opinions/ideas about this kind of courses, I have always believed that these courses should be accessible to sophomores (or even freshmen), and with an emphasis on stars, galaxies and the universe more than an "applied physics" course (specially with central forces being discussed in most classical mechanics courses and the Rayleigh limit in optic courses), this could serve the double purpose of exposing students to the wonderful ideas of astronomy even if they lack a strong physics background and help to lure students in to the more advanced astronomy courses. What do you think?

Star formation 101. Part 1

2008-01-25T13:29:00.001-06:00

The time has come to pay one of the old debts of this blog: A mini-course on star formation. The night sky is full of little twinkling stars, but despite their obvious abundance its formation is still far from being a closed case.

Gravitational collapse (a cloud of interstellar gas collapses and produces stars) is the obvious way to produce stars , but it leaves us with a startling question, we can estimate the time of this collapse using the expression:

which is called the free fall time and as you can see it only depends on the density of the cloud and not of its size, for a typical cold cloud this time is around one million years, this is obviously problematic because we know galaxies are much older than that and we can observe star formation in practically every spiral or irregular galaxy.

This indicates us that other forces are acting on molecular clouds, slowing the process of gravitational collapse. There are four hurdles that star formation has to overcome, as we will see in this star formation series it is surprising that even a single star can overcome this hurdles! This hurdles are:

The pressure hurdle: A homogeneous, spherical gas cloud is stabilized against collapse by its own pressure gradient. This means that the temperature of the cloud despite being small still implies enough energy for the particles in the cloud to overcome their own gravitational attraction. We can estimate the size at which the cloud is doomed to collapse, this is called the Jeans radius and is given by

where k is Boltzmann's constant, T the temperature of the cloud, m the mass of the particles and n the numerical density of particles. The Jeans mass is simply , when we plug numbers into it we realize that stars similar to our Sun require cooler and/or denser regions than the average of the interstellar medium. This regions are the molecular clouds.
The dynamical hurdle: As the cloud collapses it is heated, the energy required to heat the cloud comes from its own gravitational potential and it eventually reaches an equilibrium state when

where K is the kinetic energy and V the potential energy, when this condition is satisfied we say that the cloud is virialized. So we can see that star formation requires cooling, otherwise the cloud will get virialized and reach a stable configuration halting the collapse. Thermal conduction and convection are remarkably ineffective in this regions and most of the cooling is radiative.
The angular momentum hurdle: As gravitational collapse shrinks the cloud, angular momentum conservation amplifies any initial angular momentum (which is usually of the same magnitude of galactic rotation) by an enormous amount, the spin frequency is amplified by around 10¹⁶, this is such an spectacular increase in the spin that the cloud should be teared apart by the centrifugal effects. Dissipation is required to get rid of this excess of angular momentum, it is thought that this excess leads to proto-stellar disks.
The magnetic flux hurdle: Lorentz force implies that charged particles are free to move in the direction of the magnetic field but have a hard time moving perpendicularly to it, so the magnetic field behaves as a spring refusing to compression. Collisions between the charged particles and the neutral ones eventually transfer this "springy behavior" to the rest of the cloud. A process known as ambipolar diffusion eventually allows the neutral component to fall through the ionized component.

The current state of star formation is centered around two paradigms: The "standard model" based on the collapse of isothermal clouds under ambipolar diffusion and the "turbulent model" based on the redistribution of energy at diverse scales of the cloud, making some "lumps" where star formation takes place.

In future post I expect to explain you how each of this hurdles can be overcome and give an overview of this two paradigms.

No asteroid impact on Mars

2008-01-10T18:58:00.000-06:00

We ended last year commenting the possibility of an asteroid impact on Mars, this asteroid (2007 WD5) had rather small change of crashing on Mars.

The latest data has ruled out this possibility, the use of archival photos and observations from the German-Spanish Astronomical Center, Calar Alto, Spain; the Multi-Mirror Telescope, Mt. Hopkins, Arizona; and the University of Hawaii telescope, Mauna Kea, Hawaii yielded and impact probability of cero.

We will need to wait for this kind of serious fireworks in the future!

Milkomeda

2008-01-06T18:25:00.000-06:00

The local group of galaxies consists of two big spiral galaxies: our own Milky Way and Andromeda, and a rather small spiral galaxy known as the Triangulum and about 40 small galaxies of varied morphology.

Unlike most galaxies which are redshifted due to the expansion of the universe, Andromeda is blueshifted meaning that it is moving towards us. Eventually the Milky Way and Andromeda will collide, this is a bit uncertain because the only way to know for sure if the local group is bound we need to measure the radial and transverse velocities of its members, we can measure the radial speed from the redshift but transverse speeds are quite complicated to measure. Despite that, the measurements of the radial velocity of Andromeda are of 120 km s-¹ towards us and a transversal velocity of around 100 km s-¹ and it is certainly smaller than 200 km s-¹ (Loeb A., Reid M. J., Brunthaler A., Falcke H., 2005, ApJ,633, 894). Using this values we can conclude that the system is indeed bounded and that the merger is quite likely to happen.

The galaxies of the local group. Andromeda is clearly the biggest member (this doesn't means it is the most massive, we have reasons to believe that the Milky Way has more dark matter and is more massive). The only other major galaxy is Triangulum which is significantly smaller. The rest of galaxies are small and many of them have irregular morphologies like the Small Magellanic Cloud.

Kahn and Woltjer pioneered the study of the dynamics of the local group (Kahn F. D., Woltjer L., 1959, ApJ, 130, 705), they argued that Andromeda and the Milky Way formed quite closely and then separated with the expansion of the universe, then started to approach each other due to their gravitational attraction. From this suppositions they were able to estimate the mass of the local group and the size of the orbit.

A detailed simulation of this merger has been produced by T.J. Cox and Abraham Loeb (arxiv:0705.1170v1). They used a model of the local group proposed by Kyplin et al (Klypin A., Zhao H., Somerville R. S., 2002, ApJ, 573, 597) which has as much as 20 times more dark matter than baryonic matter. The diffuse intragroup medium was supposed to have a mass comparable to the mass of the galaxies. The simulations were carried with the GADGET 2 code (if you are computer and astro savvy, you can download this code and run your own simulations of astrophysical phenomena in your computer).

In this simulation we have the first detailed scenario for the Sun as the merger happens. This merger will start in less than 2 Gyr, first with tidal interactions that will create a stream of matter between the MW and Andromeda. As we mentioned in a previous post, the Earth will be out of the habitable zone in about 1.1 Gyr, unless some advanced civilization enlarges the radius of Earths orbit (Korycansky D. G., Laughlin G., Adams F. C., 2001,Ap&SS, 275, 349). Despite that, let's continue to discuss the fate of the solar system.

During the first close encounter, there is a 12% chance that the Sun will be pulled out of it's current position in the outer arms of the MW and reside in the extended tidal material between the MW and Andromeda, during this phase we expect a burst of star formation. After the second encounter the chance of residing in the tidal material rises to 30% and a more interesting outcome arises, there is a 2.7 % chance that the Sun will be captured by Andromeda. In this scenario any astronomer in the Earth will be able to see the MW (or rather its remains) from Andromeda in the night sky.

This is the simulation by Loeb et al. You can see that the collision won't be a head-on merger, but rather the two galaxies will spiral into each other, the final result of the merger is an elliptical galaxy.

After the merger is completed, the simulation suggests that the Sun will habit in the outer halo of a massive elliptic galaxy, which Cox and Loeb call Milkomeda. This is only a possible scenario using realistic assumptions about the local group, in their paper Cox and Loeb report a dozen of additional runs with different values of the density of the intragroup medium and the transverse medium and find that the outcome is esentially the same. The resulting galaxy has the R^(1/4) brightness distribution that is typical of elliptical galaxies, so our own local group will act as a prototype of the late forming elliptical galaxies.

Tomorrow the AAS anual reunion starts, so we can expect some nice news in astronomy for the next week!

Life and death of interstellar dust

2007-12-26T13:10:00.000-06:00

In this part of the "dusty posts program" we will talk about formation and destruction of dust in the interstellar medium. Before we embark on this questions we need to know at least two things about dust: its size and composition.

As we mentioned in the last post, the dust betrays its presence by absorbing light, the absorption efficiency at some wavelength depends on the size of dust grains. Absorption is a rather complicated phenomenon because there are many physical processes that can cause absorption in our sightline, light might be literally absorbed by the dust grain or it might be scattered out of our sightline. Scattering is also dependent on the ratio between the wavelength of the scattered light and the dust grain diameter. If this ratio is small we talk of Rayleight scattering, otherwise the process is known as Mie scattering.

Detailed analysis of absorption curves leads us to believe that scattering is caused by small solid solid particles which have a diameter comparable to the wavelengths of visible light (this explains the 1/lambda behavior in the visible part of the spectrum), nonetheless we still need other components to explain some features of the absorption curve.

An average absorption curve, the far infrared is on the left and the ultraviolet on the right. There are some variations in different zones of the galaxy, but the shape of the curve is usually quite similar. We can see the peak of absorption are at 200 nm (or 1/lambda = 4.6 ).

Now let's move to the composition of dust. The Sun being so close to Earth is readily observed and we (somehow naively) assume that it is a typical star and its composition is assumed to be fairly typical of the Galaxy. We can then use the Sun abundance of elements as a guide for relative abundances between it and the interstellar medium.

We know that the relative abundances of the Sun and the interstellar medium are different. The main difference is that some elements have an underabundance of elements compared to the Sun. This elements are usually refractory, meaning that this elements can survive high temperatures without being sublimated, this directly points us to dust, as this elements can condense in dust grains that can survive in the vicinity of stars. Depletion is defined as

and as we can see below, this elements are among others Cr, Fe, Ni, Co, Ti. Despite that, the bulk of a grain is quite similar in composition to the dust you can find in your backyard and is mostly divied in to graphites, silicates and olivines.

Interstellar elemental abundances compared relative to hydrogen compared with the Sun. We can see that refractory elements are heavily depleted. The depletion is a logarithmic quantity defined, meaning that some elements like Ti are depleted by three orders of magnitude.

So, how are dust grains formed? The first idea is to think that they grow slowly in the interstellar medium. The problem with this idea is that actual calculations show that this will take too much time, suppose that at time t=0 the grain has a radius r(0), if we suppose the grain grows by addition of species i with mass m_i moving at a mean thermal speed v_i then the radius at a later time t will be

where epsilon is a "sticky coefficient" that meassures the probability that the m_i will remain attached to the grain and s is the density of the solid grain. Using the typical values for interstellar medium we find that for a typical grain (about the size of visible wavelengths) the time required is

which is too much time if we consider that the value of epsilon is smaller than one, and that the age of the universe is around 13 Gyr.

The solution comes from considering denser regions, in particular the atmospheres of cool stars. The material in stars is originally so hot that it did not contain any solids, but as it outflows in later phases of the life of the star it starts to cool with much higher densities than the interstellar medium and the atoms can arrange themselves in to the most stable molecules at that temperature (usually around 10³ K). When this outer layers are ejected in stellar winds the dust goes in to the interstellar medium. There is some controversy about the formation of dust in the early life of the universe, the most accepted view is that this dust was formed around active galactic nuclei.

Now let's move to grains destruction. The simplest way to destroy a grain is to heat it enough so it sublimates. That indeed happens in the vicinities of young, hot stars. The sublimation temperatures depend on the composition and size of the grain, this results in a stratification of the dust with large graphites closer to the star, followed by smaller graphites and large silicates, at larger distances from the star we can find smaller silicates, olivines, fused quartz and silicates with ice mantles.

A more interesting mechanism comes from accumulation of electric charges in the surface of the dust, if the grain is spherical with a radius a and is carrying a charge of Z electrons then the electrons capture cross section if the speed of the electrons is u_e is given by

When enough electric charge accumulates on the surface the stress it causes on the grain as it tries to redistribute, causes the grain to literally explode! Quite an interesting consequence for the well known fact that charges redistributes on a surface!

It actually results that the capture of species by dust grains has a crucial importance in astrobiology, keep tuned!

Merry Christmas

2007-12-24T19:53:00.000-06:00

Today it's Christmas eve. Receive the warmest regards from the "staff" of this blog. On this day, 39 years ago the crew of Apollo 8 entered into orbit around Moon, so this is also an special day for space exploration. Not only that, maybe there is a quite special gift under the tree this year: 2007 WD5.

2007 WD5 is an asteroid that will cross Mars orbital path in January 30. There is some chance (around 1 in 75) that it will impact Mars! This asteroid is around 50 meters wide and might create a half-mile wide impact crater. Despite this event is rather unlikely it will cast some serious fireworks in case it happens.

You can read the JPL official press release here.

This is the orbital path of 2007 WD5, you can clearly see that it intercepts Mars orbit. The uncertainties in the measurement of 2007 WD5 path don't allow us to assure a collision will happen, actually it's quite unlikely it will occur. In a few days we will have more data.

Update: This asteroid has been recently identified in archival imagery, this has allowed astronomers to refine the orbital parameters, now the odds of a collision are of 1 in 25! Still a rather meager chance (4%), but we still need more data for a more accurate prediction.

Dust in the interstellar medium

2007-12-17T13:30:00.001-06:00

Today I will give you a brief overview of a topic that's quite close to me: the effects of dust in interstellar medium. There are some regions in the sky that seem to be almost magically depleted of stars, even in very dense regions. The classical example of this "dark nebulae" is the coalsack in the Crux constellation.

The coalsack dark nebula is the best known region where interstellar dust is so dense that it blocks all the light (in the visible frequencies) in it's sightline.

This regions are not depleted of stars, but rather the light of the stars in the sightline is absorbed by dust. This is far from obvious, after all there is no a priori reason to discard the idea that this regions simply lack any stars.

The first conclusive evidence of light absorption in the interstellar medium came from the work of Robert Trumpler who measured the angular sizes of globular clusters trying to calculate its distance from Earth. The idea was simple, let's assume that globular clusters are roughly the same size, then the smaller a particular cluster seems to us, the farther it is. When Trumpler carried on this plan he realized that the there was a linear relation between the size and the distance, i.e. the clusters were bigger as the distance to them increased. This was quite unexpected and also seemed to point to the rather disturbing conclusion that Earth is located in a special place where globular clusters are smaller.

Rather than that, Trumpler realized that the distance was systematically overestimated (so the clusters weren't that big, after all). Then he assummed that the reason for this bias was extinction in the interstellar medium, meaning that something (presumably dust) was absorbing light on its way to Earth.

Further evidence for dust comes from light polarization. When light is reflected from a dust grain it is polarized depending on the alignement of the grain, if the grains are aligned with Milky Way's magnetic field, we can then use the dust polarization as a measure of the direction of the magnetic field.

Measurements of dust polarization, this measurements show that optical polarization is aligned with the magnetic field.

What is the composition of this dust? This depends on many factors. Nonetheless the most important one is the distance to a star, particullary to hot, young stars. This stars (known as early spectral type) are so hot that that dust sublimates in its vecinity. The grains composed of carbonites are more resistent (and bigger grains have a better chance of survival), then the silicates enter the stage. In colder enviroments larger molecules appear on the surface of the grains.

How are this grains formed? Why is dust relevant for astrobiology? Which are the effects of dust on ionized regions? Keep tuned for later posts!

Doomsday

2007-12-14T18:14:00.003-06:00

What will happen to the Earth in the far future? Can humanity or it's successors live forever in it? By now most of you know the lore: the sun will eventually consume all of its "fuel" (hydrogen and later helium) in 5 billion years, expand in to a red giant that will devour Mercury, Venus and the Earth. After that the Sun will eject the outers layers of its atmosphere and leave a stellar corpse: a white dwarf which is small, extremely hot object supported by the pressure of electron degeneracy. The ejected outer layers will be ionized by the radiation of the white dwarf and form a nice planetary nebula, like the Helix.

The Helix nebula is one of the best known planetary nebulae, in the astro-lore it is usually asummed that the Sun will produce a similar nebula when it dies.

Well, I recently attended a talk by Klaus Peter-Schroeder, from University of Guanajuato, in his talk he disputed this scenario. Now, let's discuss the good, the bad and the evil ...

The good: Previous models assumed a "naive" modeling of mass loss as the Sun ejects it's outer layers based on Reimer's Law, which is basically based on dimensional arguments. An improved version of this law applied to the Sun shows that it will loose enough mass to allow Earth's orbit to enlarge sufficiently to avoid the doomsday scenario.
The bad: Well, that doesn't mean that Earth will be an habitable planet. It will be too uncomfortably close to the Sun, but you might still think that we have around 5 billon years to worry about that. Well, that's wrong. The Sun will increase it's energy output in around a billion years (still a lot of time) by a sufficient amount to increase Earth's temperature around 10 K. You might think that it will be an uncomfortable but still bearable change, nonetheless climate models predict that effects of such a change will be catastrophic.

In "The End of the World", the Doctor travels to Earth's last moments before being engulfed by the Sun. In the show the writers imagined that some "gravity satellites" held back the expansion of the Sun, we now know that it will be tidal dragging to blame for Earth's destruction.
The evil: Well, life on Earth will end one day, but at least will Earth survive to total destruction? Not really, despite that the Sun won't grow enough to engulf Earth, a process known as tidal dragging (you can think of it as a sort of "tidal friction" assisted by dynamical drag) will cause the Earth to spiral into the Sun! The model is extremely sensitive to little details, but we can estimate that the doomsday will happen just 500 000 years before the Sun reaches the tip of the AGB branch.

So the lore is actually quite wrong in practically every detail, but wait! There is still a final twist to this plot. The nice planetary nebula that will act as a sort of mausoleum to the star that made life on Earth possible actually requires stronger stellar winds than the Sun can provide. This is still a point of controversy, but at least among the attendants the consensus was the Sun might produce an irregular planetary nebula at best.

Addendum: It results I was being very naive with the raise of temperature. In Klaus own words:

"It is 1 Gyr for a rise of 10% in the solar irradiance, which makes the Earth leave the habitable zone. But in order to raise the temperature by just 10K, we need much less time! It is difficult to compute because a detailed knowledge of the various positive (and negative) feed-backs is required, but it should be of the order of 100 mio years. That is still very long compared to the timescale of the current climate change....! "

Modest Understanding of Lie Groups Part 0: U(1)

2007-11-17T22:51:00.001-06:00

This semester I had the pleasure to take a very little nice course on mathematics, mathematics for physicists that is. What this means is that half the course we dealt with lie groups and the remaining month or so we studied path integrals. Now, why is this interesting? It just happens to be the sexiest mathematics available to me at this point.

In case you didn't know, finding symmetries in physics leads to a deeper understanding of the phenomena at hand. This is obvious to any undergraduate student facing for the first time electromagnetism. The most basic problem of this course is finding the electrical field a distance d above an very long line of uniform density charge. Needless to say, you want to know how much the line would pull (or repel) a charge, should you feel like putting one a distance d above it. Of course you don't need to understand much about physics to eventually see that it doesn't matter where you place it, as long as it is a distance d perpendicular to the cable. Clearly this is because the line of charge is very long and this places are practically the same to the line. From this information you then can guess that the electric field must only depend on the coordinate perpendicular to the line, a trivial conclusion, but proves the point just fine I guess.

Again, why am I talking about this? Turns out our most precious tool (for the moment) allowing us understanding the world, the Standard Model, is based on symmetry groups. Namely it is usually represented by SU(3)xSU(2)xU(1). Let's start by understanding the simplest part of this: U(1). Imagine a circle, or rather, its points:
In this figure, A and B are two points on the circle. All the points on this circle are characterized by some properties. For example, if a point on the circle is represented by the vector

the point

is also on the circle! Having seen this, it's easy to see that the points on a circle with the operation of addition (since each point is characterized by an angle, we can understand it as the sum of their angles) form a group. If we see this circle on the complex plane, a point on the circle can be represented by a complex number

and a rotation about the center of the circle will be given by multiplying this number by the following phase factor

This will take us

that is, another point on the circle (closure). If this is new to you, try and find the identity and inverse elements.

We can see this phase factor as a 1X1 matrix, and call it U. It's clear then that in this case

But in general for bigger matrices

I hope then to have explained how this implies that the complex numbers of norm 1 form a group under the operation of multiplication. This group is the most simple I can think of for now, the U(1) group (unitary matrices of rank 1, which satisfy the last equation).
Tune in next time for a brief explanation on all the other classic groups.

Everyone salute the blogino

2007-11-03T11:20:00.000-06:00

Last may Symmetry magazine launched a contest for inventing new particles, and the results are out in the latest edition. One of the particles is so relevant for this humble site that it deserves special mention: the blogino, it's creator Jacobo Konigsberg from Fermilab says about it:

Particles created by non-abelian Blog-Blog interactions. Bloginos typically are produced in a very excited state and with a high degree of spin. Even though all their properties have not yet been determined, it is commonly agreed that they exhibit considerable truthiness. They also have the annoying ability to propagate into extra dimensions, away from the blogosphere, and generate lots of phone calls.

The allmighty blogino, the coolest particle around only behind...

The rockon "discovered" by Ike Hall from Fermilab was, hands down, my favorite particle:

Responsible for such things as face-melting guitar solos, heart-pumping rhythms, screaming vocals, and hair bands. Observation of the rockon over the airwaves has been on the decline since 1995.

Yep, that particle really rocks. It's particullary close to me since rock is what I most like in life!

Comet Holmes from OAN-SPM

2007-11-01T16:21:00.000-06:00

Comet Holmes is an old folk for astronomers, discovered in 1892 and with a period of 5.9 years, it was discovered in an outburst during which the comet brigthened to a magnitude around 4-5.

A similar outburst happened last october, from magnitude 17 to 2.5! It is still visible at the dusk (or dawn) if you look at Perseus, maybe some binoculars will be necesary. I won't delve further into it because there are many posts about it in the blogosphere (1)(2)(3), rather I'll show you a nice pic of this comet.

Use this sky chart to look for Comet Holmes, it depicts the sky at a latitude adequate for most of North America and Europe.

Alan Watson, an astronomer at Centro de Radiastronomía y Astrofísica, UNAM was at OAN-SPM (National Astronomical Observatory at San Pedro Martir), and used the 1.5 meter telescope to take this nice picture of comet Holmes in the R band (meaning light was filtered to only allow "red" light arrive the detectors).

The exposition time was 10 seconds. Look at the displacement between the core and the coma.

Are the laws of physics emergent ?

2007-10-24T17:55:00.000-05:00

Last monday I attended a fascinating conference by Robert Laughlin (who won a Nobel Prize for his remarkable work on fractional quantum hall effect). The meadow of his arguments is this: the behavior of the world is ultimately governed by emergent phenomena.

Let's say a kid wants to know how some simple device works, he will surely try one thing: dissasembling the device, look at each part and figure out how they work. This is what Laughlin calls the reductionist approach. Physicis has been carried this way for the past centuries, this is how we arrived to our knowledge of elementary particle physics, by dissambling the matter in to smaller chunks at increasing energies.

Emergent phenomena arraises when collective behavior suddenly becomes different from the behavior of it's individual parts, this pinpoints to one of the fundamenal characteristics of emergent phenomena: universality. This means that the collective behavior is esentially independent of the properties of it's individual parts.

This was exemplified in a funny way by Laughlin who showed Newton burried under a big pile of apples, which is an obviously different behavior from that single apple in Woolsthorpe. Note that for the sake of beeing buried under a big pile of something it won't make a difference to be buried beneath apples, watermelons or potatoes.

One of the really perturbing things mentioned by Laughlin was that Newton's first law is actually emergent and comes from a broken symmetry, this was totally unexpected for me, but maybe one enlightned reader can bring some light to this issue (please!).

But, are fundamental laws of physics emergent? There is no doubt that emergent phenomena is important and quite interesting. And of course, every reasonable physicist will tell you that we don't need to know the detailed behavior of quarks or QED for describing biology or weather.

Whatsoever I don't honestly believe we can have a complete/satisfactory knowledge can be acquired in this way, we actually need to know from where this laws emerge from. As an example, how are we going to figure (say) the properties of fundamental particles? It seems to me that if you keep asking "why?" you eventually need a detailed description, the sort of fundamental physics we have always think about.

And, this might be just a wrong perception but it seems to me that the "reductionist approach" is far more general, at least in the sense we only need to know the law of gravity (and dynamics, of course) to compute the behavior of an arbitrary number of apples, this also applies to any other system where gravity is acting. On the other side you need to have a "lot's of falling things law", "orbital's motion law", "single falling ball law", etc...

Halley's debris

2007-10-20T11:24:00.000-05:00

During the year, earth's orbit crosses the paths of hubris left behind by comets. When this debris enters the atmosphere it is heated by friction and it's temperature raises dramatically making them quite easy to spot, this are the so called shooting stars.

When the earth crosses a dense stream then the number of shooting stars (usually close to one per hour in the whole sky) meteor showers occur. Some well known meteor showers are the Perseids and the Leonids (usually boring, the Leonids can produce the most spectacular meteor showers evey 33 years including the meteor shower of 1833, usually considered the most spectacular ever).

Tomorrow's night (October 21-22) the Orionids will reach their peak, in the north you can expect 20 meteors per hour and 40 in the south.

Use this starmap (from meteorshowersonline) to watch the orionids, the stream of meteors will look as emerging from a radiant, the radiant is quite close to red bright star Betelgeuse.

Remember that this means 20 meteors in the full sky, and to be honest this shower isn't as reliable as the Perseids, nonetheless it is a nice weekend activity.

The source of the Orionids stream is the famous Halley's comet, so you are actually watching little pieces from this comet as they enter the earth, quite amazing if you think about it, there are even missions where high altitude planes collect this comet dust.

Cool Nerd King

2007-10-17T23:51:00.000-05:00

Are you facing the ultimate question: Am I a nerd? The website NerdTests.com offers you the answers you always wanted. In particular in my trip to the oracle I got:

Oficially I am a cool nerd king, whatever that means. Submit your results to the comments section!

First light ... and some Sudoku!

2007-10-17T18:55:00.000-05:00

Well, hello to all of you, kind blog readers, whoever and wherever you are. This is my first post, or making reference to what observational astronomers say when a new telescope captures its first image ever, this is my first light.

I think Luis already mentioned the main points concerning myself. I've been fascinated with Physics, Astronomy and Computers since I was very little, so getting into numerical astrophysics was an inevitability of fate, it seems. In case I seem too geeky, I should note that I also enjoy movies, music, videogames and drinking beer/tequila like there's no tomorrow.

My current research is focused towards numerical models of DEM L316, a pair of supernova remnants in the Large Magellanic Cloud that were caught in action, ie: two supernovas that might have exploded near to each other and thus may now be colliding.

-

Now, time for some Sudoku! For those of you who don't know, Sudoku is a simple number game, where one must fill the blanks in an incomplete 9 x 9 number grid, following a simple rule: a number may only appear once in each row, each column and in each of the nine 3 x 3 blocks of the grid.

I spent most of my afternoon writing a Sudoku solver. Since I'm a bit rusty with my programming skills, I thought it'd be a good exercise. The program is written in C++ and I've compiled it under SuSE 10.3 (which I've just installed on my laptop and works wonderfully).

You can download my Sudoku solver here.

It's a gzipped tarball. I've also included a binary compiled in SuSE 10.3. In order to compile the source in your own distro, if you have the GNU C++ compiler just type "g++ -o sudoku sudoku.cpp". The grid to solve is entered in the data file sudoku.dat, which should be in the same directory as the binary. I've included the hardest grid I've found (for my solver) as example; it takes 605,484 trials to solve it.

The algorithm behind the program is simple. It's a brute-force recursive algorithm. This means my algorithm solves Sudoku by trying a valid number in the first empty position, then trying a valid number in the next grid position, then the next, etc ... all this done through a recursive function. When the function finds it cannot place a number in a particular position, it goes back to the last grid position, and tries the next valid number there... again, all this done recursively.

In the end, it works very well and fast enough (despite being an exhaustive algorithm). It takes well under a second on my C2D T7100, 2GB RAM laptop to find the solution to any grid I've fed the program. The program is nice since it makes use of recursion, which is a powerful feature of programming languages. As the creator of Ghostscript, L. Peter Deutsch, put it:

To iterate is human; to recurse, divine.

As is to be expected, the greater the number of blanks to fill, the more trial number placements the program must do to achieve a solution. However, there is no clear correlation between the reported difficulty of a particular grid and the trials needed by my code to solve it, other than the fact that harder puzzles usually have a larger number of empty squares to fill.

And Now for Something Completely Different...

2007-10-11T21:13:00.000-05:00

A man with string theory up his nose.

As our gracious host has already pointed out, I'm actually a physics student, so it's an honor to be able to write for this fine astronomy blog. In any case I'm beginning to understand the AdS/CFT correspondence, which as you may already know, deals with the apparent duality that exist between some string theories and quantum field theories.
What we can aspire to do with this approach is to investigate quantum field theories without relying on perturbation theory, which limit our understanding of nature. For example, Quantum Cromodynamics (QCD) enjoys asymptotic freedom at high energies, this means that since interactions are weak at those energy scales it's sane to use perturvative methods. However in cases where energy scales are small, we simply do not know how to perform calculations. As always numerical methods are useful to some extent, but even they have a hard time dealing with some situations (they involve dealing with some dynamical quarks, as far as I know). Other option is to study the AdS/CFT correspondence and gather bits of information about gauge theories in general. It all boils down to this: either, A) Find a string theory dual to QCD to be able to make calculations or B) Understand properties about gauge theories in general so you can make predictions about QCD. The second option is more viable and has had success in the past. But I'll explain that some other time.

Since I'm just starting studies on this subject I hope I'm not making some false statements, (I'm not, as far as I know). Feel free to comment on the subject should you feel otherwise.

On a side note, Toots Thielemans is playing tomorrow at Netzahualcoyotl Concert Hall, one of Mexico's most beautiful concert halls in my own opinion. This will be interesting...

What makes this blog thick?

2007-10-11T19:37:00.000-05:00

Counter services are one of those little modern wonders, allowing to track the number of visitors to a site, the country of origin, the browser they are using and most importantly what keywords they used to arrive to the site.

So, which are the more popular keywords in the last 100 visits? Let's take a look:

mexican scientist, mexican astronomer
Yes. That's just what we are.

mexican astronomy
You have just come to the right site, you can have a little glance at astronomy done in Mexico from firsthand participants, mostly students, but still firsthand participants.

iraf ubuntu, ubuntu iraf, ubuntu iraf package, install ds9 ubuntu
Fine, enjoy the scripts. You can still say you compiled IRAF yourself, just to impress your (geeky) friends.

astronomy package octave
Sorry, but octave is an interpreted numerical language quite similar to Matlab and it lacks astronomy specific packages (you can update me on that), maybe if you have some astronomy package for Matlab it will work on octave.

mexican scientist famous, important mexican scientist
Get back in a few years...

luis.sanchez
What!!! Who is google stalking me? I should lock the door right now...

Claudio Toledo: our latest adquisition

2007-10-11T12:41:00.000-05:00

Juan Claudio Toledo (also known as Meithan West in the underworld) has joined our blogging team. He is a grad student at Instituto de Astronomía, UNAM, where he works on astrophysical fluid dynamics and interstellar medium (yes, this blog is populated by ISM researchers).

He is currently working on numerical simulations of astrophysical fluids (this usually means a fluid that is self-gravitating and usually ionized), so hopefully he will bring his numerical expertise to this site.

With his addition this blog is now almost a chilango blog!!! Well, that should be remedied soon!

Welcome Claudio!

Eric joins the team

2007-10-09T21:37:00.002-05:00

I proudly announce the addition of Eric Pulido (from a dual approach) to our blogging staff. He is currently a physics grad student (yes, this blog is driven primarly by students) at Universidad Nacional Autonoma de Mexico, as far as I can say his interests are in theoretical physics, mostly at string theory and cosmology (allowing me to call him an "astronomer").

Besides bringing his stringy expertise to this blog his addition will move the center of gravity of this blog a bit in to Mexico City.

Welcome Eric!

Nobel to giant magnetoresistance

2007-10-09T20:13:00.001-05:00

I have always been very impressed by this modern devices capable of storing vast ammounts of data in a quite reduced space.

This devices had been possible by giant magnetoresistance, an effect discovered in multilayered materials (Fe/Cr/Fe trilayers and Fe/Cr multilayers). The effect manifests itself as a significant disminution in the resistance of the material in the abscence of a magnetic field, this has been implemented in the reading heads of hard drives allowing the data to be stored in really weak magnetic fields.

Giant magnetoresistance is widely regarded as the birth of spintronics, in particular in giant magnetoresistance the spins of the electrons of the nonmagnetic metal align parallel or antiparallel with an applied magnetic field in equal numbers.

This work got the nobel to Albert Fert and Peter Grünberg, who had just won the Wolf Award this year, so this prize wasn't a complete surprise for anyone, and it is actually the recongnition to some really remarkable research that has lead in to devices that everyone uses on a daily basis.

Ok, I'll read the manual

2007-10-08T20:08:00.001-05:00

In my latest procastination attack I stumbled over this masterpiece of contemporary humor. If you change the toaster by my computer then the situation starts to feels quite familiar for me. Check xkcd for more great comic strips (just in case you didn't knew it before).

Nobel Hype 2007

2007-10-07T18:20:00.000-05:00

The next week the winners of the Nobel prize will be announced. As usual there is always some fuzz speculating who will win. As usual I declare my own ignorance of the whole selection process. Whatsoever I can always say who are the obvious candidatates in the astro related areas: Alan Guth, Paul Steinhardt and Andrei Linde for inflation (although Andreas Albrecht was also crucial and a quite similar mechanism was proposed before by Starobinsky), and the leaders of the Supernova Cosmology Project and the High-z Supernova Search Team that found evidence of the acceleration of the expansion of the universe. Now, considering the prize went to cosmology the last year I don´t think it will be awarded again to a related area this year. Dark matter also deserves a nobel, but it's history is too long, although Vera Rubin is the usual suspect. Thomson scientific has a stadistical based prediction, saying that Martin Rees will win the prize.

What about other areas of physics? Well I am certainly less savvy about that, I have always believed that James Bjorken who found the scaling law for QCD deserves the prize and also Yoichiro Nambu along with Jeffrey Goldstone for the bosons that appear in simultaneously broken symmetries. The SNO experiment showing that neutrinos indeed oscillate is another crucial contrubution.

On the rest of physics I don't feel like making some sort of prediction, but of course, your predictions are always welcome.

Resurrection day

2007-09-24T16:33:00.001-05:00

After a really long hiatus I have decided to bring this blog back to life, mainly because I really enjoyed writing it.

In the mean time I have been quite busy (which is why I haven´t posted for so long, of course), in particular with some calculations of the mechanism that keeps HCHII regions (relatively small clouds of ionized gas around young massive stars) confined. Expect some posts on this.

Getting IRAF the easy way

2007-01-16T13:19:00.006-06:00

If you have ever reduced astronomic data, then is almost sure that you know the IRAF package. Despite being old and cumbersome this package is unvaluable for image reduction and analysis in astronomy.

However it's installation is a quite involved ritual, well, not anymore. Realizing that the entry where I discussed a debian package for IRAF was the most visited one, I am posting a much better solution: installation scripts, you can use this scripts for installing IRAF (and related packages like ds9) in ubuntu, and in Scientific Linux (this script should also work in Opensuse and Fedora). Just download them anywere and follow the instructions on screen. This scripts are only small modifications from the original one by amd77. Just make sure you have installed csh (it is in the universe repository in ubuntu and quite probably in the distribution media of Fedora and Opensuse) , you just need to run the comand: bash installiraf_* and enter your password in Ubuntu or the root password in other distro, so here are the scripts (links not working):

After running the script you should run the command mkiraf for creating a login.cl file, I have that file in my home directory but you can put it anywhere, just remember to start iraf (the command is cl) from the same directory.

Update:

Since I posted this (quite a long ago) there have been all sort of changes in of libraries/packages included in modern distributions. Since there is no simple way to address this isssue (there are 6 versions of Ubuntu, 6 of Fedora and 5 of opensuse in the past 3 years, and that not counting that both come in 32 and 64 bit versions) I declare the scripts dead.

Nonetheless, an iso image which includes an useful installer is now being offered at: http://www.astro.uson.mx/favilac/downloads/ubuntu-iraf/iso/IRAF_Ubuntu.iso. Just keep in mind that it only works for 32 bit kernels (which are the majority of installed kernels, anyway).

The same autor also offers a (rather outdated) set of rpms at http://www.astro.uson.mx/favilac/downloads/IRAF/ . Find out which one is better suited for your distro and add it to your repos. I have not tried to install from these rpms so I can not comment on them.

For users of 64 bit systems only solution I know is to actually download iraf from iraf.net and proceed to install as detailed in the installation manual.

News from the AAS meeting

2007-01-10T13:18:00.001-06:00

This week in Seattle,Washington will be held the 209th meeting of the American Astronomical Society. This a very important event and there have been some quite interesting results already anounced.

The findings of the COSMOS team consisting of a weak lensing survey of a 1.6 square degree patch of the sky have gathered a lot of attention. This a rather big portion of the sky (around 9 full moons), this technique measures the distortions (gravitational lenses) produced by the mass between the source objects and the observer, I had already discussed it in relation with the Bullet Cluster. We now have a map of the dark matter in this region of the sky and it shows clearly how the dark matter is getting clumpier by the effect of gravity. I won't go into further details, mostly because many others (Clifford, Phil, Sean, Angela) have already blogged about it.

Another interesting announcement has been the detection of a Triple Quasar using the Keck telescopes and the VLT by a team lead by George Djorgovski. This system known as LBQS 1429-008 was already known to be a doble quasar, but the new deep images show a faint third member. This is interesting mostly because it supports the idea that quasars are more frequent in intereacting enviroments as the gravitational interactions throw large ammounts of material in to the central black holes of this galaxies. You can find more info here.

Stay tuned for more news, this week will surely have more interesting findings!

Watch for comet McNaught, today!

2007-01-10T13:07:00.000-06:00

Comet McNaught has brightened this week to the point it is readily observable, even in large cities! If you are living at northern latitutes and have a clear southwestern sky you can try to watch it, it might be a very nice sight. Depending on your latitude you can watch it up to the friday or saturday.

The comet should be very low, close to the horizon, at 15-20 degrees from Venus (depending of your latitude). For more detailed instructions go to SkyTonight.com site, they also have a nice photo gallery.

Books invasion!

2006-12-01T22:34:00.001-06:00

We are having our book fair this week and many remarkable figures like: José Saramago, Gabriel García Márquez and Rigoberta Menchu have visited the city. This event has grown every year and it seems this year is at least as successful as others.

I have had the oportunity to get some nice books, for example some nice lecture notes from UNAM in perturbation theory and variational calculus.

One really remarkable book I have just found is: Differential Equations: Theory, Technique and Practice by George F. Simmons and Steven Krantz. This book is at freshman-sophomore level (for an excelllent advanced text look for the text by Arnol'd ) and is, hands-down one of the best math textbooks I have ever read, it includes many interesting applications (Hamilton's principle, Lagrange's equations, Kepler's Laws, Vibrating membranes, Pursuit curves) and almost always succeeds in delivering crystal clear explanations of the topics it treats. Not only that, it really feels like a modern textbook and includes many topics not found at this level: Sturm's separation and comparison theorems, Liapunov functions, Poncaré-Bendixson theorem and stability of dynamical systems. It also includes a chapter on calculus of variations, and many historical notes. I really wish the course on ODE's I took was half as interesting as this book. Despite some places where I think a further discussion is necesary (like the Fourier transform and numerical methods) and some turgid passages (Picard's theorem could a bit clearer) this is the obvious choice for an student wanting to learn differential equations and enjoy the ride. (And, no, the publisher isn't paying me, I really like this book).

I also got the relativity book by W. Rindler and it seems to be a welcome addition to my library (If you want my recommendations, use: J. Hartle's Gravity for undergrad and Sean Carroll's Space and Geometry for grad students, Schutz, MTW and Wald are standard books and there is much to learn from them). By the way, can someone recommend me some book on thermodynamics-statmech that is actually readable?

On other topic, maybe you have already watched the pathetic show (1)(2)(3) displayed by our lawmakers, even if it may look the country is in crisis, actually life is going as usual and most of this silly events don't have much importance at all (besides generating press coverage). One interesting thing will be to watch Calderon's attitude toward scientific research, Mexico has one of the lowest science budgets (at least in terms of the gross income) in the OCDE, let's see if this finally changes.

An historic day for mexican astronomy

2006-11-22T18:17:00.000-06:00

Today the LMT (Large Millimeter Telescope) has been inaugurated today by president Vicente Fox. This telescope is a landmark in mexican astronomy. The LMT is the largest single dish radiotelescope working in the millimetric wavelengths (1-4 mm). It is located in the top of Sierra Negra, a 4,640 metres (15,223 feet) mountain in Puebla that was chosen for it's high altitude and dry air that avoids atmospheric absortion of millimetric radiation.

The LMT has a diameter of 50 metres and was a 150 millon investment that was built in 10 years ina cooperation between INAOE and UMass.

Millimetric wavelenghts are usually emitted in the coldest and densest places in the universe, this are the most oscured enviroments in the universe (the earliest stages of structure formation usually take place in sites) and observations at high resolutions had been scarce (there are also plans for large interferometric arrays at this wavelenghts like ALMA), this powerful new instrumention will finally allow us to solve some long standing problems in astronomy like high mass star formation.

The main scientific goals of the LMT are studies of structure formation in the universe, for example it will allow to observe directly the molecular cores where star formation takes place. It will also allow observations of the dust disks around young stars allowing us for first time a glimpse into planet formation. Other interesting proyects planned for the LMT are observations of some dusty starburst galaxies at large redshifts, obervations of the AGN's and studies of the center of the Galaxy that is remarkably difficult to study because the dust blocks light in almost all wavelengths, actually almost all our knowledege of the galactic core comes from radio wavelenghts, so this new window will surely give us many surprises.

Watch for earth-gazers

2006-11-18T21:07:00.000-06:00

If you are living in New England and the eastward parts of New York State and Quebec watch out for the leonids. This are particles from the comet Temple-Tuttle and are usually a meager show, but every 33 years the Earth enters in a particullary rich part of the stream, this actually happened in the 1998-2002 period, with the 2001 leonids beeing the most remarkable meteor shower in decades, so we are out of the "sweet spot".

Despite that, today (saturday 18) the earth passes through a narrow and dense part of the filament, if you live in the zones mentioned above then at around 11:45 pm east time (04:45 UT) you can expect a nice show, Leo won't be quite high in the sky so don't expect a literal rainfall of the meteors, the nice thing about tonight's meteor shower is that the meteors will enter the atmosphere at a low angle producing very long trails known as "earth gazers". If you are lucky enough to watch this from one of this places please leave a comment!

So, stop reading this and look in the direction of the Leo constellation, now! If you don't know where to look you can use the skycharts at SkyTonight.com.Look for more details (inclyding a map of the trail) here, if you can't see the country in the map (like me) you are out of luck.

Science is for everyone, isn't it?

2006-11-12T00:12:00.000-06:00

In 1995 Roger Schlafly found a very large prime number and then somehow managed to patent it! Can you really "patent" a number? Well, it seems the answer is yes, but legal issues aside the whole notion of pateting numbers lacks any sense, at least for me. So, are technological patents a good idea?

The central problem is that while patents might somehow encourage sharing information because at least everyone can see the patent and eventually the patent will expire (compare it with secrecy like the coke recipy that might never be known) the current "lawsuit culture" has gone to really funny extremes and some very nasty ones like software patents (you need to pay royalties for patented things like scroll bars, at least in principle).

I have just read an unbelievably funny story in this regard (even funnier than Sagan vs Apple), it seems that Kimberly-Clark was using some patterns quite similar to Penrose Tilings in toilet paper, of course Mr. Penrose (who has done many remarkable things in mathematics and physics) didn't liked such a close link with the lavatory and sued Kimberly-Clark! You can read an account here.

Personally I find that science belongs to everyone and there is no sense in trying to prevent it's widespread use, even in the lavatory.

Setting up your scientific workstation

2006-11-08T12:08:00.000-06:00

Usually setting up your computer as a scientific workstation has been a very time consuming activity, for MacOS users scisoft has been avalaible for a long time (it also has a version for Fedora Core 3) and includes most of the software that an astronomer is likely to use and it is useful for practically every other branch of physics, after all the numerical, ploting and statistics software has lots of applications.

Now a very useful script is avalaible for Ubuntu, it is called scibuntu and will turn your ubuntu system into a scientific workstation in a snap.

The culture of corruption

2006-10-06T22:07:00.000-05:00

Raymond Fisman and Edward Miguel published a quite interesting study. They wanted to study the cultural influence on corruption and devised a way to do it: they measured the parking violations of diplomats in NYC.

Because of diplomatic inmunity there is almost zero enforcement of the law, so the cultural effects should be evident. The results are quite interesting:

As you can see in the figure the countries with the most negligent diplomats are also countries with high indexes of corruption and poverty. Of course we can argue if corruption causes poverty or poverty causes corruption. Which are the countries with no parking tickets? Unsurprsingly enough: Canada, Israel, Norway, Sweden, and Denmark. This are highly devoloped countries, showing again the correlation between poverty (or lack thereof) and corruption.

My opinion: the only reason for diplomats for parking where they pleased is the culture of corruption, they knew they could do it and get away with it, so why not doing it? This is the kind of mentality that keeps countries in the thirld world.

Nobel prize for the COBE team

2006-10-06T21:45:00.000-05:00

As you might already know, the Nobel was awarded to John Mather and George Smoot, the leaders of the COBE project that measured the CMB determining it's blackbody form and detected anisotropies on it (this anisotropies are the seeds of the structure in the universe), this was a turning point in the history of cosmology allowing for first time a detailed comparison of cosmological models with CMB (which is esentially a "picture" of the universe when it cooled enough to allow the presence of neutral atoms). According to the Nobel Prize committee, "the COBE-project can also be regarded as the starting point for cosmology as a precision science.

The most detailed study of the CMB has been carried by the WMAP satellite and it is consistent with the predictions of inflation which makes us believe we are on the right track. ESA expects to launch the Planck Surveyor probe in 2008 which will complement the studies of WMAP and might even be capable of detecting the polarization in CMB due to gravitational radiation.

Congratulations to Mather and Smoot!

Nobel Hype 2006

2006-10-01T21:46:00.000-05:00

The winners of the Nobel Prize in physics will be announced next tuesday. I don't have any firm prediction but I am willing to hear the ones from you!

In the field of astrophysics this prize was never awarded to its greatest figures: E. Hubble, the greatest observational astronomer of the last century who opened the whole fields of extragalactic astronomy and observational cosmology and Y. Zel'dovich who was the greatest astrophysicist of all times, is simply almost impossible to work in a field to which Zel'dovich didn't made a contribution: the theory of nuclear chain reactions, the physics of plasmas, black holes (he was one of the first to develop evidence of the "no hair" black holes, he also proposed them as the mechanism behind quasars), the evaporation of black holes, the production of monopoles in the early universe and many other contributions in other fields including chemistry and optics.

Of course there are many fields of physics with probable candidates (David Deutsch, Peter Shor or Anton Zeilinger,or the Sudbury neutrino experiment for example), I will only speculate on astrophysics. Ignoring the fact that the Nobel has eluded some of the best in the field I think that the inflationary trio (A. Guth, A. Linde and P. Steinhardt) has a very good chance of getting the prize. The more we study the CMB, the more consistent it seems with the inflationary scenario, despite that we lack a 100% confidence in it, although the vast majority of cosmologists consider the inflation as the correct answer, and that is also my own opinion.

In the observational field there is an obvious Nobel candidate: The two teams that discover the aceleration of the expansion of the universe (hands down the most important discovery of the last decade in all physics) and the COBE team for discovering anisotropies in the CMB. Dark matter also deserves a Nobel Prize but there are too many names associated with, altough V. Rubin is the most common and there is no doubt of the existence of dark matter, so she another solid candidate.

Play the game! I'd like to hear your suggestions.

Dissecting movies

2006-09-16T19:23:00.000-05:00

I have recently landed a website with a very noble cause: dissect the bad physics in movies. The website is called insultingly stupid movie physics. Of course most of us go to movies just for fun, but Intuitor seems to attend movies with the only purpose of analyzing its physics.

This site features some generic stupid movie physics and reviews of particular movies with ratings going from GP (good physics in general) to XP (obviously physics from an unknown universe).

Have fun.

Au revoir Pluto!

2006-08-24T19:52:00.000-05:00

The rumours started last tuesday and today were confirmed: The IAU did not aproved the proposed redefinition of a planet that would many members to the planetary neighborhood, not only that, now Pluto is no longer a planet!

This was the correct decision (so we finally admit there was a mistake made more than 70 years ago) but I was surprised when the news arrived on tuesday that most astronomers not only wouldn't vote the proposed definition but actually wanted Pluto out of town. I definitely didn't expected that the IAU would demote Pluto as a planet, mostly because astronomers have always been very much conservative, take the horrible magnitude system as an example (we have a very ugly system for measuring fluxes that was made only to agree with some measurements done in the classic Greece!).

On the other side the decision to call Pluto a member of a new class of planets, the plutons, instead of just calling it a planetoid is silly and was fortunately rejected so Pluto is now a "minor planet". The obvious name for this kind of objects is planetoids and everyone out there is using it but somehow the IAU doesn't thinks that, but well... what can I do on that regard?

The Smoking Gun

2006-08-21T20:32:00.000-05:00

This morning in a press conference the first direct evidence of the existence of dark matter was announced. As I previously mentioned the conference was about the Bullet Cluster, a quite remarkable cluster that consists of two colliding clusters of galaxies. Let's put it clear and loud, this shows undeniable evidence dark matter exists and there isn't any need for modyfing the laws of gravity (at least for macroscopic scales).

This is the Bullet Cluster at optical wavelenghts, the bunch of galaxies in the upper right form one of the two interacting subclusters, in the bottom left corner you can the second (and smaller) interacting cluster.

The concept of dark matter isn't really that new, it was proposed by Fritz Zwicky in 1933 who realized from observations of the Coma Cluster that the speeds of the galaxies in the cluster were too high to keep the cluster bounded, he realized the mass of the cluster should be 400 times greater to keep it together and although later observations showed some of this mass there was still less than the required to explain the motions of the galaxies. We have now evidence in many clusters, also the mass infered from gravitational lensing is always bigger than the mass from the observed galaxies, even in our own milky way the stars in the outer regions of the spiral disk orbit at higher velocities than we should expect from the observed mass.

There are two straightforward ways to explain this observations:

There is more mass than we observe, this can be because it cames in the form of cold objects than don't emit much light (like the funny named MACHOs and brown dwarfs) or from some kind of matter that interacts very weakly with "normal" (baryonic) matter (these are called WIMPS, an obvious and funny match for the rival of baryonic matter). The latter explanation is much favored because the MACHOs and brown dwarfs seem to contribute only a small fraction of the missing mass.
We need to modify the laws of gravity, a particular popular model of this type involves a modification of inverse square depence of gravity and is called MOND. Despite its problems in explaining some observations regarding gravitational lensing it was (until this morning) a more or less viable explanantion.

After observations with the Chandra X Ray Telescope Markevitch et al (1,2) it was possible to observe the gas component of the cluster (in clusters of galaxies most of the mass -around 90%- is in the form of a very hot gas that emits x rays) and it showed clear evidence of a recent interaction between the two clusters. This collision heated the gas even more, as far as I know this is the hottest known cluster.

The Bullet Cluster in x rays is shown in the pink zone of the picture. Two shock front on the right corresponds to the smaller cluster, this front has the highest mach number of all the known intergalactic medium

The most interesting part comes now, the galaxies in the clusters actually don't crash and rather pass by without changing that much, but the remaining matter in the gas forms about 90% of the mass of the cluster and we can use the x ray observations to see if the source of gravity points in the same direction where most of the observable mass is located. What makes the Bullet Cluster so special is that the galactic component is separated from the gas element, as dark matter (by definition) interacts very weakly if it interacts at all it will be in a position similar to the galactic component that passes almost unperturbed the interaction.

But how can we know where gravity comes from? One of the most surprising predictions of Einstein's theory of general relativty is that gravity can bent light in the so called gravitational lenses, the paper by Clowe et al (3) shows the weak lensing map of the bullet cluster maping the location of the mass in the cluster.

The blue part of the picture maps the position of the matter causing the weak lensing in the background galaxies. As it turns out it is a map of the dark matter of the cluster!

Now, if you expect that the laws of gravity should be modified to explain the rotation curves in galaxies and the motions of galaxies inside clusters then you should expect at least that the weak lensing map points in the same direction of the observed matter, after all it's gravity should produce the weak lenses. It turns out that both the weak lensing and xray maps are well separated with the weak lensing map in the same position of the galactic component just as expected from dark matter!

This image shows the x ray emission in pink and the position of the mass causing the weak lenses in blue, as you can see most of the mass of the cluster is not in the observed xray emission and is actually just in front of the observed galaxies clearly showing that it has not interacted with the hot gas component. If this is not convincing enough for you then anything will be.

This shows conclusively that most of the matter in the Bullet Cluster is not in the observed x ray emission (and much less in the observed galaxies) but in an "invisible" component that only manifests through its gravitational presence. You can see here an animation of how we think this process happened. There is simply no way to fit any alternative theory of gravitation in it, the principal source of gravitational mass is simply not observed in any light wavelenght. Regarding the composition of dark matter this is one of the biggest unsolved problems in astronomy and physics, my personal guess is that is composed mostly of axions and light supersymmetric particles (the lightest supersymmetric partner turns out to interact really weaky and is stable as it can't decay into a lighter particle), but again it's just my guess.

Images courtesy of NASA, you can see more images here.

What a week !!!

2006-08-17T18:48:00.000-05:00

This week has been really active in astronomy: There is some new discovery about dark matter that deserves a press conference on next monday (from the participants list that includes Cosmic Variance´s Sean Carroll and Maxim Markevitch I can bet it will regard the Bullet Cluster, John Baez actually has the same guess) this cluster is really interesting and it certainly deserves a future post in this blog (maybe before monday´s press conference) , a team reports to have found the limit between main sequence stars and brown dwarfs and it is 8.2% of the mass of the Sun, but undoubtely the event that is getting most attention is IAU´s new definition of a planet that is going to be discussed at IAU´s reunion in Prague.

Actually this is not a redefinition of the planet concept, the truth is that we have never had a definition at all! The reason is that of the current nine accepted planets six were known since prehistoric times (when people used FORTRAN and hunted woolly mammooths) because they are easy noticeable in the sky (changing it's position everyday and not blinking as stars). When W. Herschel discovered Neptune and the posterior finding of Uranus (which was predicted by theoretical calculations!!!) it was clear that they were very similar to the known planets so there wasn't much contreversy.

Using the same theoretical arguments it was expected that a ninth planet would eventually emerge and Clyde Tombaugh eventually "found" it at Lowell Observatory in 1930. It was only decades later when it's "moon" Charon was found and it became possible to approximate Pluto's mass, this mass is so small that it has a negligible effect on the orbits of the other planets (another interesting feature of the Pluto-Charon system is that the center of gravity of this system is outside of Pluto, so both orbit a common center somewhere between them) so the question remained open and the existence of a "Planet X" was expected (at least by a few astronomers). Today we know that the data used for the "theoretical" prediction of Pluto was simply wrong and there is nothing as a "Planet X", although high precission measure of the orbits of the probes Pioneer 10 and 11 seem to point to some source of perturbation a major planet is not in the possible explanantions.

Recently the problem of defining a planet has emerged from two principal sources:

The extrasolar planets found using diverse techniques seem to be way more massive than Jupiter (the most massive planet in the solar system) and some of this planets were found so close to it's star that it challenged the model of planet formation of that time and it's still a bit problematic. It was hard to know where planets end and stars begin.
Searches for trans-neptunian objects started to show "minor planets" that are of almost of the same size of Pluto, actually one of them, Quoar, seemed to had the same size as Pluto, then some even bigger transneptunian objects were found like 2003 UB₃₁₃ (Xena), Sedna, Orcus and 2005 FY₉.

This has generated much controversy about what is a planet, as our current list of planets seems to include an object that is esentially a big asteroid (Pluto) and some really big extrasolar planets that are almost stars. So the IAU has proposed the following definition:

A planet is a celestial body that (a) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (b) is in orbit around a star, and is neither a star nor a satellite of a planet.

Using this definition the solar system would increase inmediately to 12 (planetary) members, and the new folks in town will be: Ceres, Charon (so the Pluto-Charon system would be considered a double planet) and Xena. There are other obvious candidates like Quoar that would enter the planet definition as soon as astronomers confirm their properties. The definition also includes a new class of planet: pluton that applies to all planets similar to (ughh) Pluto.

These are the "new" planets, one of them (Ceres) has been considered for long time as an asteroid of the asteroid belt between Mars and Jupiter.

In my personal opinion this "new" definition is nonsense, despite it is based on a scientific and unambigous definition it simply adopts a "leave no big icy rock behind" and this "new" solar system is way too messy (specially for the public, after all the definition isn't really that much relevant for astronomers), the solar system will have eventually hundreds of planets that have little (if any) in common like Ceres and Jupiter. Not only that, this definition is completely ambigous on the other end of the spectrum and leaves the separation between brown dwarfs and big planets as blurry as it can be. It is expected that the resolution will be decided on August 24th. Many of my peers are in Prague waiting impatiently the result of this resolution, I will inform you about it as soon as I can.

Look at some of the new candidates for planets, all them are very small, actually some of the moons of Jupiter and Saturn have the double (or more) of its size. Just compare the size of Vesta and Pallas (in the asteroid belt) with the size of the earth.

Some astronomical humor

2006-08-14T15:22:00.000-05:00

I recently landed up in this page (almost by accident), if you have ever done data reduction then you might want to take a look at it. Despite I have never used AIPS, I am somehow familiar with IRAF and the "paleolithic mysticism" is also there, and yes the "painful blows" described there are mostly true. Happy reading.

A regional view

2006-07-28T00:27:00.000-05:00

This certainly won't be new to anyone in the region but is important to summarize Latin America 's position in science and technology, and the results are terrible. In a report done by the Inter-American Development Bank (get the numbers here, also check the report on higher education) the data was hard to believe. As an example the whole region spends $11 billion in research and development, this might sound like an awful lot of money but now consider that a single asian country, South Korea, expends $12 billion, more than all the latin american region!

The reasons for this are difficult to pinpoint, but as far as I can say the whole topic isn't in the political agenda. In the past electoral process the candidates rarely mentioned it, maybe they just expected that inversions will arrive to a country that is unable to create any new product. In this regard Mexico registers the ludicrous amount of 82 patents a year! Argentina registers 62 patents and the regional leader, Brazil, registers 130 patents a year. There are many US universities that register many more patents. Let's compare this numbers with Asia, Japan registered 36 000 patents, South Korea around 3000 and China (that has comparable or higher levels of poverty) registered 300.

The research is sponsored mainly by the state which is a rare situation in the world. In the "communist" China 61% of R&D is paid by the bussiness sector in contrast with the 32% in Latin America. The bussiness sector inversion in R&D of course isn't the result of some philantropic ideology but the result of effective state policies, as an example many american universities get money for research from donations that many companies do in exchange of fiscal privileges. But don't expect that transnational companies will put their money in countries with high taxes, inefficient spending, legal uncertainty (remember Evo Morales seize of refineries and oil extraction plants or the seizure of bank deposits in Argentina in 2001).

Even more important, Latin America lacks the necessary human resources to attract R&D inversions that usually go to places like India or Singapur. Take the microprocessors company Intel as an example, most of the region's countries were shocked when Intel decided to move its inversions to Costa Rica (where president Arias removed the army and used those resources for education) instead of the obvious candidates: Mexico, Brazil and Argentina. Even further in the past Intel had looked at the region for a big R&D plant but eventually decided to do it in Haifa, Israel (which is now under fire, literally). In this regard the educative levels are pathetic, in the PISA mathematics test the average score of mexican students was 385, the american students scored 483 and japanese students 534.

Which are the results of this lag in science, research and education? The results are that the region is the slowest-growing one in the development world, while Latin America is projected to grow by 3.7 percent in 2007, sub-Saharan Africa will grow by 5.4 percent, the Middle East and North Africa by 5.1 percent, South Asia by 6.2 percent, East Asia by 8.1 percent and Eastern Europe by 5.1 percent. It is imperative for the region to understand that the current situation is untenable: the oil prices won't be sky-high forever and the agricultural and metal export prices increase will certainly decrease in future.

In a region where its leaders speak about the recent export bonanza as the product of their economic wisdom, the future might be gray when the bonanza bubble bursts unless the correct measures are seized. Certainly science, research and education should be the prioritary model for the region's growth and as Ireland and Asiatic example shows, it works.

Blasting out black holes from the galactic disk

2006-07-13T19:11:00.000-05:00

A recent paper (1) shows that the black hole X-ray binary XTE J1118+480 might be an ejected black hole from the galactic disk. This system consists in a small star orbiting a black hole, it was discovered in the year 2000 and it was since then an interesting object because of its location in the metal poor galactic halo.

Using the 10 m Keck telescope the spectra of the small star has been observed and surprisingly enough it was very rich in metals (remember that in astronomy anything else from hidrogen and helium is considered as metal, this is because this elements are synthetized inside the cores of stars, elements heavier than iron are believed to form in supernova explosions) suggesting it might actually be a double star from the galactic disk (where the metal abundance is much higher than in the halo), when the massive star in the system went supernova it might caused an asymmetrical blast (by the so called "acoustic mechanism") that expelled the system from the galactuc disk (2).

After reading the paper it seems to me that the metallicity is way too high, it's even higher than the Sun, this means that

This is a relatively recent event so the star is from a later generation than the Sun, so it formed from a mollecular cloud with a higher metal abundance.
As I mentioned before some of this heavy elements are formed in supernova explosions, making the assymetric natal kick not so necesary, after all.

Because the estimated age of the small star is around 5 Gyr, so the first scenario is very likely and certainly (almost) discards the origin of this system inside a globular cluster.

EurekaUK

2006-07-08T22:10:00.000-05:00

There is a recent report from UK universities about the most remarkable discoveries done in UK universities, in a previous post I had done a similar thing for the mexican case.

Despite some points in which I disagree, like the claim of the contraceptives which were first sintetized in 1951 by Luis Miramontes in Mexico who was aware of the contraceptive use of norethindrone (the work in 1961 by Herchel Smith produced cheaper contraceptive pills which is of course a significant advance, but it seems clear that the report try to sell the idea that contraceptive pills are an UK invention which is false), and also the CFC stuff where the really important role was played by Crutzen, Molina and Rowland (again the work of James Lovelock was an important precedent, but it seems to me they are trying to oversell it), this kind of reports are really important because many countries are facing serious problems with research budgets.

In the case of Mexico the situation is of near disaster with only 0.34% of the gross domestic product going to research despite some countries invest more of the 10%. This situation has only resulted in that most of the inversions in technology have gone to Asia where the situations is radically diferent, let's see how the new president faces this challenge.

No the best possible outcome

2006-07-05T20:41:00.000-05:00

We still don't have an official result of the elections, the cause is simple: Andres Manuel Lopez Obrador has acussed everyone of massive fraud, including the loss of 3 million votes (the votes were indeed in the Prelimary Results Program, so this was completely disproved) and has threatned threatened with massive protests and said: "The stability of the country is at stake" (1). The prelimary results with 98.5 of the votes counted showed that PAN won by around 1% (around 400 000 votes), after counting the 3 million votes that are hold the PAN still wins by 0.6% (250 000 votes). With such a close election, has said Andres Manuel Lopez Obrador "The political stability of the country hangs in the balance." and it seems clear he simply won't accept his defeat soon.

This photo actually portraits very well my impressions of this protests, the placard says "fraud" next to the the latest elections since 1988 (actually the election of 1988 is widely regarded as fraudulent, and even one of the candidates died on suspicious circunstances after the election), despite since 1994 the IFE has organized the elections and all of them had been considered as valid by international organizations. The top of the placard acusses of the fraud the PAN, PRI (their principal competitors) and TV Azteca (this is completely ridiculous, despite it dubious antecedents I don't see how this TV network can alter the ballot boxes). I won't even comment about the URSS flag...

This is one of the worst scenarios, the PRD won't accept its defeat, and the stocks have already lost 4.3%. The IFE has decidied to recount every vote tallie.

As of 8:59 PM the results are PRD: 36.45 and PAN:34.83 but many districts in which PAN had most of the votes aren't counted yet. Wait, now at 9:15 are rumors the count has halted!!!

Update: The rumor was simply false and the stocks have been stable recently, this recount has actually showed the same results: in the preliminary results Calderón won by 0.6%, in the recount he won by 0.57%. Obrador has impugned the election and has treatened with more protests, has acussed the IFE of being a corrupt and fraudulent institution, called Vicente Fox a traitor to the country and even acussed his own representants of selling out. This will only affect his own political future, personally I just want him to shut up.

Not yet...

2006-07-03T00:12:00.000-05:00

We still don't have an official winner of the election, the election is simply too close for call and the results will be announced until wednesday. It seems that Felipe Calderon has won but we only have 9% of the votes counted, in the election for legislators exit polls show that PAN has 35% of the votes and PRD a 31%.

Despite who turns out to be the next president, the PRI which ruled for more than 70 years before Vicente Fox has now falled to the third place! I don't have any idea if the PRI is prepared for this. The other source of concern regards Andres Manuel Lopez Obrador who has hinted won't accept a defeat by a close margin, there are some concerns about movilizations, but let's wait until wednesday for that.

Elections day

2006-07-02T18:11:00.000-05:00

Today we have elections for president and in some states (including Jalisco, where I live) we also have governor elections.

Amazingly enough, Mexico city has what I perceive as two rather good candidates: Demetrio Sodi and Beatriz Paredes, the amazing part is not only having decent candidates, but that the exit polls show that Marcelo Ebrard who was sacked by Vicente Fox after Ebrard refused to help three federal police officers who were lynched in Tlahuac is winning with 52% of the votes! During the hours long incident which ended in the death of two of them and included officers' pleas for help in national TV, authorities refused to send any kind of reinforcements, later videos showed that Ebrard was aware of the situation but refused to act because he was in a precampaign act. He also famous for wasting millions of dollars for Giuliani's services that didn't improve the security in Mexico city at all. The only reason I find for this is that PRD has been able to emulate the structure of PRI the party that ruled Mexico for more than 70 years, after all most of the people surrounding Ebrard and Obrador are well known members of Carlos Salinas de Gortari cabinet.

Andres Manuel López Obrador was Mexico City's mayor at the time of the incident and said that he would never use the public force, even in extreme situations as lynchings, he also mocked of the million of participants in march demanding the end of the recent insecurity wave, when months later were released TV ads showing victims of kidnappings and encounters with criminals he said he was the"victim of a complot". A few months before members of his cabinet were videotaped receiving millionare bribes from Carlos Ahumada and Carlos Ponce (the minister of finances) was videotaped gambling huge amounts of money in Las Vegas, a few days ago Ahumada's wife threatened to show more videos involving more López Obrador collaborators, and later suffered an attempt on her life, this videos are now believed to be lost. He is now the leading candidate for the presidency, don't even try to ask me why.

In the local election for governor Emilio González Marquez seems to be the winner of the elections, at least from exit polls that show he has 46% of the votes. The campaign for local elections was pathetic, even worse than the federal one and just consisted in a trade of insults and acussations, including acussations of narcotrafic, corruption and homesexuality. Of course this only results in most people view of politcs as the less honorable job in the world.

Law prohibits the release of any kind of result regarding the federal election before 9 PM in local media, I don't know if this blog is considered as a local media, but I will remain on the safe side. Maybe some international media releases some information, surely a web search can help in that regard.

Still alive

2006-07-01T00:21:00.000-05:00

After a brief hiatus I'm back to action. Actually it seems a lot of things happened recently including a failure of Hubble's main camera, an expresident got a warrant order, and, of course, the World Cup (Mexico lost against Argentina...), and I still can't believe what happened to Denice Denton. Meanwhile I have been deciding where to go for vacations, a small town in Austria seems quite interesting...

Weird ideas

2006-06-13T10:02:00.000-05:00

I attended yesterday some presentations on diverse topics of current research. This sessions were intended for the students of an introductory course in modern physics and I presented a little talk about baryogenesis, you can get it here (in spanish), as the course didn't cover cosmology in its (large) list of topics I actually spent a large fraction of the talk in some elementary concepts like the Friedmann equation and the critical density.

One of the talks was actually very intersting for many reasons, it was a 6d extension of the old Kaluza-Klein theory that was worked by a local faculty member some years ago when he was at Moscow State University. The intersting stuff is that he claimed that the model could reproduce the Glashow-Salam-Weinberg theory of electroweak interactions, unfortunately the talk was pressented by a student that was unable to give absolutely any detail of how they arrived at that conclusion (I have requested the original author a copy of the article, I'll post it when I have it), but the most interesting result was that they derived that some constants were changing in time (this is not a really new idea) and among the changing constants was e, the unit of electric charge.

Although it would be an amazing discovery this simply looks wrong, changing the value of e over time would change the fine structure constant (α ≡ e^2/h bar c ≈ 1/137). However there have been many attempts to check if α is constant and any of them have found nothing, you can look at a recent one here (the published article is here). Look at Sean Carroll's entry on changing constants (in his case it is the ratio between the mases of the proton and electron) here.

At the end of my talk I was bombarded by questions that sounded to me like the stationary universe: the idea that the universe looks the same in time, this needs some matter creation mechanism (otherwise the density would change in time). I actually went to explain that practically anyone in the astrophysical community believes in this kind of theories, that CBR really looks like blackbody radiation and it lacks the polarization one would expect if CBR is light from ancient stars which has been scattered by galactic dust (the usual explantion of CBR in steady state theories), and that we have a really big body of evidence that suggests that indeed the density is changing some members of the audience still seemed to prefer to just ignore the bulk of experimental evidence.

I don't want to state a debate here (there are so many intersting debates at Peter Woit's blog "Not even wrong"), but it really concerns me that a (rather small, to be honest) fraction of the theoretical community is so distanced from the experiments.

New Ubuntu release

2006-06-01T10:21:00.000-05:00

The latest version of the popular linux distribution Ubuntu has been released today. I don't really find necessary to post a review here because there are many excellent reviews in Distrowatch, but if you need some scientific software running in linux keep reading.

In observational astronomy the most important software package is undoubtly IRAF, you can get it very easily following this instructions, the other famous astronomy package is the now dead Starlink, the debian version of it runs nicely in Ubuntu.

Adding additional repositories will allow you to install lots of scientific apps easily using synaptic, among them are the numerical libraries gsl and scipy, the matlab clone GNU Octave, fortran compilers, latex editors like Lyx and Kile, computer algebra systems like maxima and yacas, the TexMacs interface, the fast numerical app yorick, R, Cernlib, plotting sotware like GNUplot and kst, QCad and many other apps.

Units

2006-05-27T18:12:00.000-05:00

In a recent post in Cosmic Variance, Sean Carroll recalls his personal experiences when talking about the metric system in the US, one of only 3 countries that have not officially adopted the SI system. What really amazes me is that even in physics we have some remarkably poor decisions about units, the usual decision to measure E (the electric field) and B (the magnetic field) in different units seems to me ridiculous and is a common point of confusion among begginers (so E and B compose the electromagnetic field but each one has different units?), probably the reason for this is that the mks are much more popular in engineering but I still insist that cgs units avoid obscuring the structure of the theory. I also dislike some modern physics textbooks that in the chapter devoted special relativity never get to writing time as ct, for a nice discussion of this (and other topics in SR) look at the classic book Spacetime Physics by Taylor and Wheeler.

On practical issues it just seems that not adopting an almost worldwide systems of units is more of a hassle than just adopting it, specially because many units are similar (the meter is just a bit larger than a yard and a pound is almost half kilogram). There have been some remarkable incidents in this regard that are noteworthy: In 1983 a Boeing 767 jet ran out of fuel at 12 000 m (40,000 feet) with 61 passengers aboard, this was caused by a units issue, this is the origin of the Gimli Glider expression in western Canada which means making a spectacular foul-up, also the US$ 125 million Mars Climate Orbiter was destroyed by a metric mixup.

Finally, there is article about this metrification issue in Wikipedia where you can read the different approaches to this problem in many countries, probably US can follow the example of Ireland in this regard. Look at the map showing the countries that use the metric system, only the black ones don't use it.

Happy Towel Day !!!

2006-05-25T22:41:00.000-05:00

Today is Towel Day! If you have read Douglas Adams' book The Hitchhiker's Guide to the Galaxy you can remember that a towel is the most useful object around:

"The Hitchhiker's Guide to the Galaxy has a few things to say on the subject of towels. A towel, it says, is about the most massively useful thing an interstellar hitchhiker can have. Partly it has great practical value—you can wrap it around you for warmth as you bound across the cold moons of Jaglan Beta; you can lie on it on the brilliant marble-sanded beaches of Santraginus V, inhaling the heady sea vapours; you can sleep under it beneath the stars which shine so redly on the desert world of Kakrafoon; use it to sail a mini raft down the slow heavy river Moth; wet it for use in hand-to-hand combat; wrap it round your head to ward off noxious fumes or to avoid the gaze of the Ravenous Bugblatter Beast of Traal (a mindboggingly stupid animal, it assumes that if you can't see it, it can't see you—daft as a brush, but very, very ravenous); you can wave your towel in emergencies as a distress signal, and of course dry yourself off with it if it still seems to be clean enough. More importantly, a towel has immense psychological value. For some reason, if a strag [non-hitch hiker] discovers that a hitchhiker has his towel with him, he will automatically assume that he is also in possession of a toothbrush, face flannel, soap, tin of biscuits, flask, compass, map, ball of string, gnat spray, wet weather gear, space suit etc., etc. Furthermore, the strag will then happily lend the hitchhiker any of these or a dozen other items that the hitchhiker might accidentally have 'lost'. What the strag will think is that any man who can hitch the length and breadth of the galaxy, rough it, slum it, struggle against terrible odds, win through, and still knows where his towel is, is clearly a man to be reckoned with." (The Hitchhiker's Guide to the Galaxy, Chapter Three).

I actually forgot the towel in the morning just to be reminded of the importance of the day by classmates... ohh well, I hope you enjoy this day.

Urban legends

2006-05-20T14:54:00.000-05:00

We have all heard this urban legend: A student arrives late to a class (or test) and tries to solve a particullary difficult problem posed in the blackboard which later turns to be an unsolved problem. Well this story is true and has happened (as far as I know) at least two times.

The first story regards George Bernard Dantzig, famous for the simplex algorithm and also one of the founders of linear programming. Here are Dantzig's own words:

During my first year at Berkeley I arrived late one day to one of Neyman's classes. On the blackboard were two problems which I assumed had been assigned for homework. I copied them down. A few days later I apologized to Neyman for taking so long to do the homework - the problems seemed to be a little harder to do than usual. I asked him if he still wanted the work. He told me to throw it on his desk. I did so reluctantly because his desk was covered with such a heap of papers that I feared my homework would be lost there forever.

About six weeks later, one Sunday morning about eight o'clock, Anne and I were awakened by someone banging on our front door. It was Neyman. He rushed in with papers in hand, all excited: "I've just written an introduction to one of your papers. Read it so I can send it out right away for publication." For a minute I had no idea what he was talking about. To make a long story short, the problems on the blackboard which I had solved thinking they were homework were in fact two famous unsolved problems in statistics. That was the first inkling I had that there was anything special about them.

To be honest I don't really know which theorems are the ones mentioned in this story, but I found a paper of that time (1940) that should be the one mentioned in the story:

G. B. Dantzig 1940. On the non-existence of tests of "Student's" hypothesis having power functions independent of σ, Annals of Mathematical Statistics, Volume 11, number 2, pp186-192

If someone has access to it let me know. You can see a version of this story in snopes.com.

The second story regards a very nice theorem in differential geometry that I know well: the Fary-Milnor Theorem. The legend says that John Milnor (a classmate of the famous John Nash), was sleeping in class while the proffesor explained three unsolved problems in knot theory and when he woke up he copied from the blackboard the three problems (which he assumed were assigned as homework). A week later he turned in solutions for every problem!!! Among these problems was the Fary-Milnor theorem. This gives me an opportunity to discuss this nice theorem.

The curvature K (which should be the greek letter kappa) is a function with real values over some set C (which denotes a parametrization by arc length). This theorem says that if we calculate the total curvature (by doing the integration in the trajectory) then:
if the parametrized curve C don't have any knots, this means that C can be deformed in to a circumference without been teared. Of course if C has knots then
Actually the total curvature is always bigger or equal than 2*pi and only equals 2*pi if C represents a circumference, just as we should expect. The formal statement of this result is the Fary-Milnor theorem.

John Milnor would later receive the Fields Medal for his proof that a 7-dimensional sphere can have several differential structures (28 to be exact), this result opened the field of differential topology

Science In Mexico

2006-05-13T22:29:00.001-05:00

I have been trying to write an entry about science awareness in the country but for some reason I have not been able to finish it. One of the points I try to emphasize is that despite most people knows the quacks like Jaime Maussan or Carlos Trejo (the first one is known worldwide for a series of ufo related scams, and the former claims to have detected ghosts making him a clear candidate to join the faculty of a new degree offered by Coventry University), few of them can name a mexican scientist and the general idea of the people here is that Mexico hasn't made any contribution to science.

My humble contribution to remedy this consists in offering you the following facts about science done by mexican scientists:

Vanadium was discovered in Mexico by Andrés Manuel del Río.
The first oral contraceptive (norethindrone) was invented in Mexico by Luis E. Miramontes, Carl Djerassi and George Rosenkranz of the mexicam company Syntex. In 2004, the invention of Luis E. Miramontes was chosen as the twentieth most important one of all the times. The election was organized by SCENTA, an initiative of The Engineering and Technology Board of the United Kingdom.
Mario Molina (Nobel Prize in Chemistry, 1995) discovered the role of CFCs in the depletion of the ozone layer.
Guillermo Haro discovered the Herbig-Haro objects, he and his coworkers discovered flare stars, paving the way for the theory of star formation. The three color technique for Schmidt plates developed in Tonantzintla turned to be crucial in the detection of quasars. The work of Guillermo Haro and colleagues paved the way for making astronomy the strongest science in Mexico.
Microquasars were discovered by Luis Félipe Rodríguez in collaboration with the argentinian astronomer Félix Mirabel.
The famous Alcubierre warp drive a theoretical (don't expect any faster than light ship to be constructed) mechanism of superluminal speed is the work of Miguel Alcubierre.
Marcos Moshinsky's work (the transformation parenthesis for functions of harmonic oscillation) was fundamental to the study of nuclear structures.
The theory (and observations) of star formation has received crucial contributions by mexican astronomers like Jorge Cantó, Susana Lizano and Arcadio Poveda.
Carlos Frenk (the second most cited scientist in Europe) is mexican and has made crucial contributions to cosmology, particullary in the issue of structure formation
Guillermo Gonzalez Camerena patented the mechanism for the first color TV (consider the number of hours you have enjoyed this invention).
Manuel Sandoval Vallarta pioneered the efforts to understand cosmic rays, showing clearly that the rays were composed by charged particles (and not gamma rays as tought at that time) attracted by the Earth's magnetic field (this is known as the Lemaître-Vallarta theory). An experimental group in Mexico city lead by Luis W. Alvarez carried a series of experiments proposed by Vallarta, showing that cosmic rays are mostly composed by protons and showed the east-west effect.
Antonio Lazcano, the author of the best-seller The Origin of Life is a world leader on the study of the emergence of life and one of the pioneers of astrobiology.
Do you know that Jacob Bekenstein (the first to suggest the entropy of black holes) is mexican?

There are still more contributions for which I don't have time to put in this post. I hope this survey of mexican science helps a bit to change the vision of many people, this people certainly deserves more recognition from the society. With such an scarce founding (this has been even worse recently with the adminstration of Vicente Fox who simply doesn't understand the importance of science in the development of the nation) the work of this scientists is even more noteworthy.

Trends

2006-05-11T14:03:00.000-05:00

I have been playing with the latest gadget from google labs: Google Trends. It seems it appeared last year but it wasn't avalaible to general public until now.

Some of the results are amazing, in science the trends by region are clearly dominated by Asia showing clearly the importance of science in that region. Now let's look at the cities, for the term astrophysics, the searches are concentrated in: Pasadena (home of Caltech), Oxford (UK), Cambridge (UK), Bangalore, Cambridge (USA, home of Harvard and MIT), New Delhi, Mumbai, Chennai and Delhi, all of them in India.

In particle physics Oxford (UK) and Geneva (home of CERN, the biggest particle physics laboratory in the world) clearly dominate the scene with Cambridge(USA) in a distant third place. I couldn't resist to compare the trends in astrophysics and particle physics, and the results show that astrophysics is a bit more popular, but there is a peak in particle physics around mid 2004 when it surpassed astrophysics, I don't know the reason for sure, I speculate it is related to the results of the RHIC.

PD: If you live in Mexico you should find this trends quite interesting. The reason that the red line (the one corresponding to the PRI) don't appears is that the term do not have enough search volume to show graphs! You can even follow the trends of the leading candidates to presidency, the results are fascinating, you can see how the popularity of Andres Manuel Lopez Obrador was unbelievably high during the impeachment process but currently he is way below Felipe Calderon, you can even see how Felipe Calderon was completely unknown before 2005 then matched the popularity of Roberto Madrazo and is now in the lead (at least in terms of web presence).

Wow

2006-05-09T12:29:00.000-05:00

Alejandro Satz has published in his blog a link to the coolest lab report ever. You can see this gem of research here.

I can only imagine if this report was actually handled to the grader or if the author just invented it. Anyway read it now, you can not afford to miss it.

Can we test M Theory in the LHC?

2006-05-08T21:42:00.000-05:00

A few years ago if you told someone that higher dimensions could be detected with current technology they would certainly look you as a crackpot. The idea of additional dimensions is older than you might think, it actually goes back to the work of Kaluza and Klein (in the 1920's,) who discovered that if we introduce and additional spacial dimension curled in a really small radius to general relativity the resulting set of equations not only included the Einstein field equations, but also Maxwell equations!!! Despite it eventually failed as a unified theory of gravity and electromagnetism the idea was explored again when theories of supergravity suggested that in 11 dimensions the unification of all known forces could be possible. In the early eighties it was clear that supergravity wasn't the answer to unification (it was not renormalizable), but a few years later the famous result by Schwarz and Green that superstring theories in 10 dimensions were free of anomalies, anyway by the beginning of the 1990's the field was starting to stagnate, until the work of Polchinsky and Witten showed that the different string theories were only different descriptions of a single theory and also that 11 dimension supergravity was a low energy approximation!!! During this time the additional dimensions still were considered as small and curled, avoiding any realistic attempt of detection.

The announcement that 10-D string theories and 11-D supergravity were related was considered the second string revolution, in this revolution not only strings but also new objects called branes came into spotlight. The branes lead to to the Randall-Sundrum models, in this models our Universe is a five-dimensional space and the elementary particles except for the graviton are localized on a (3 + 1)-dimensional brane or branes. Since this models were proposed the detection of higher dimensions seems possible.

The approach is to create a high energy graviton which could leak in to the extra dimensions and disappear. Of course we do not detect directly the graviton, but we can see that energy and momentum were carried by some invisible particle. So this is the simplest kind of experiment you can do, and if you can eliminate other kinds of possibilities for things that carry off energy invisibly, you would then be able to claim that you've seen evidence for extra dimensions of space. Let's be honest, rather than a test of M-Theory this is really a test of large additional dimensions and not of M-Theory itself (we don't even know it's dynamics), anyway the Randall-Sundrum models are clearly the products of some ideas introduced in the second string revolution and any experimental evidence of them will clearly show we are in the right track.

You can see a technical account here by Joe Lykken. Anyway you should note that the real chance of detecting this additional dimensions in the LHC is very small, even in the proposed ILC that should allow us to do better measurements in this issue the chances are scarce, but the nice thing is that we have at least a chance to do an experimental confirmation of the this models.

By the way, if you are on the Loop Quantum Gravity camp, there are also some experimental predictions (concerning light propagation) which I will comment in a future post that are actually accessible and can definitely verify or falsify the theory .

Increase your wisdom

2006-05-06T20:57:00.000-05:00

The brightest contemporary thinker, George W. Bush has contributed so many intellectual jewels that Jacob Weisberg has decided to compile them online, so all the world can enjoy them.

I can't resist to put some of them here for your intellectual delight:

"Those who enter the country illegally violate the law."
—Tucson, Ariz., Nov. 28, 2005

"I think we are welcomed. But it was not a peaceful welcome."
—Philadelphia, Dec. 12, 2005, on the reception of American forces in Iraq

"It's a time of sorrow and sadness when we lose a loss of life."—Washington, D.C., Dec. 21, 2004

"This notion that the United States is getting ready to attack Iran is simply ridiculous. And having said that, all options are on the table."—Brussels, Belgium, Feb. 22, 2005

"I believe that, as quickly as possible, young cows ought to be allowed to go across our border."
—Ottawa, Nov. 30, 2004

“Mr. Vice President, in all due respect, I’m not sure 80 percent of the people get the death tax. I know this: 100 percent will get it if I’m the president.”
— George W. Bush, St. Louis, Mo., October 18, 2000

And finally some insight on how he arrives to his impressive results:

"I'm also not very analytical. You know I don't spend a lot of time thinking about myself, about why I do things."—Aboard Air Force One, June 4, 2003

The full collection of wisdom is available at:

http://www.slate.com/id/76886/.

Have axions been observed?

2006-05-06T13:56:00.000-05:00

Unlike the electroweak force (as shown in the famous k long and k short decay experiments), the strong force described by QCD (Quantum Chromodynamics) doesn't seems to violate CP parity, despite QCD allows CP-violation.

In 1977 a model was proposed by R. D. Peccei and H. R. Quinn to explain this. It essentially introduces a new broken symmetry. It's associated Goldstone Boson(essentially a new particle associated to a spontaneously broken symmetry) was called an axion, in an obvious reference to a brand of detergent.

One nice thing about this model is that the axions have no electric charge and interact very weakly with matter, making it an obvious candidate for the dark matter, specially because the theory suggest that axions were created abundantly in the Big Bang. While there haven't been any direct observations of axions, the experiments haven't ruled them out, either.

The PVLAS experiment found a tiny light polarization rotation in strong magnetic fields which seem to suggest the existence of axions. You can read an accessible account of the result here. A second experiment CAST might be able to detect axions from the Sun.

Despite the current results from PVLAS are suggestive at most, a direct detection of axions (maybe by CAST) will have a big impact on our understanding of dark matter.

Double Jeopardy

2006-05-04T13:23:00.000-05:00

In astronomy there is a well known double jeopardy problem. The number of observatories is small compared to the number of projects requiring telescope time, and it is usually the case (in USA, at least) that you have money for the project but no telescope time, but it can also be the case that you have telescope time but no money to travel. Well I am currently in the second situation !!

In Mexico we have a very productive but rather small astronomical community, with around 100 astronomers plus grad students, but of course many of them work in theoretical models that do not require observational time. We have 3 big optical telescopes, two of them are in the OAN (Observatorio Astronomico Nacional) property of UNAM one of 2m and the other a 1.5 telescope (they also have a big refractor in Tonantzintla, , the remaining one is a 2m telescope in the Guillermo Haro Observatory property of INAOE. The point is that having access to telescope time is not as hard as it is in other countries where the ratio between astronomers and telescope time is much smaller (you still have to write a good proposal, of course).

Our team (working in extragalactic astronomy) got a HUUUGE share of telescope time in the two telescopes of the OAN, 3 weeks to be more precise, and I was supposed to observe in the 1.5m telescope some near elliptic galaxies in infrared. Well, that is scheduled for tomorrow and my wallet is as empty as it can be! Other members of our team will go and I think that we have enough people to do the observations (mainly because a colleague from Birmingham is coming).

The ugly part of things is that I actually requested funds but we (me and two other students) only get less than the half of the requested funds, and the funds wont arrive until june, at least!! It seems that I need better sources of financing. =(

Report 2010

2006-04-26T17:45:00.000-05:00

Today the particle physics report 2010 was released. I haven't read the full document (around 140 pages), but from the press release it is obvious that US is planning to regain the lost territory after the cancelation of the Superconducting Super Collider and will actively back the construction of the ILC in the US.

On the astro side, the LSST (Large Synoptic Survey Telescope), an 8.4 meter telescope with an amazing 10 square-degree was among the proposed projects. Similar in purpose to the Sloan Digital Sky Survey (SDSS) with an obviously higher deepness, showing around 10 times more galaxies than a similar SDSS field, to get an idea of the data that the LSST will collect take a look at the DLS site which is doing a similar survey with a much smaller telescope (around 4 meters) and a much smaller field. The most impressive part of this is that LSST will cover 50 000 times (yes 50 000) the area of the images of the DLS and in 5 bands!!! Such amount data will change astronomy even more than the almighty SDSS.

Keep tuned.

The latest Flying Spaghetti Monster sighting

2006-04-23T14:54:00.000-05:00

A very funny article on the Wichita Eagle tells the story of a teacher who had a poster of the FSM ... when members of the State Board of Education were touring the school. Read the full story here. It seems evident to me that this Saucy Creator is everywhere!

Scientific McCarthyism

2006-04-23T13:16:00.000-05:00

While the Bush administration has never been much versed about science (remember intelligent design?) some of the recent facts described by Phil Plait about ¨Mr. Deutsch, a 24-year-old presidential appointee in the press office at NASA headquarters whose résumé says he was an intern in the “war room” of the 2004 Bush-Cheney re-election campaign¨ are really outrageous. Trying to teach intelligent design in schools is almost like teaching sorcery and I really can't visualize it happening in any modern country, but to supress the facts about global warming (rememeber Bush has been an oil entrepeneur for long time) will have even far reaching consecuences. While there has been some considerable polemic about the reality of global warming, the position of Bush and pals is really based on profit and not in any scientific study.

Ohh yes, you should read how they consider the Big Bang a "mater of opinion". Of course, you should rememeber DeLong's Law: “The Bush Administration is always worse than one imagines, even when taking into account DeLong’s Law.”

Will Mac OS X go open source ?

2006-04-22T13:38:00.000-05:00

Beeing myself a fan of both MacOS and Linux seeing the column of John Dvorak at http://www.pcmag.com/article2/0,1895,1950222,00.asp was a surprise. As you may know the new Intel based macs are capable of running win xp natively creating a lot of fuss around them. If you have ever run MacOS you already know that is currently years ahead of windows, and with more than half of pc's around not capable of running the future Windows Vista it seems that the moment for exploring an alternative operating system.

If MacOS goes open source, the battle Linux-MacOS will surely get all the spotlights turning them away from the Redmond camp, or at least that is what Dvorak suggests. Very nice prospect indeed. For now I will remain in the Linux camp, while using MacOS for my laptop, as I have always find turning any Linux distro into a usable laptop OS a real headache.