Laser 50 anniversary

This year it's 50 year anniversary of laser. There is a special website about that, laserfest.org, quite a few interesting links there...

In fifty words or less

In his book “Indiscrete thoughts” famous Italian-born American mathematician Gian-Carlo Rota mentions that Stan Ulam was used to say “Whatever is worth saying can be stated in fifty words or less”.

Well, these days he would probably adjust it a bit:

“Whatever is worth saying can be stated in 140 symbols or less”

)

The LHC will be launched tomorrow

You may follow it online: here is a live display of the beam status. You may also follow CERN on twitter.

via cherstn (friends-only)

Creating magnetic monopoles in table-top experiments

An interesting article appeared today among PRL Editor's suggestions: Ville Pietilä and Mikko Möttönen "Creation of Dirac Monopoles in Spinor Bose-Einstein Condensates". These guys theoretically describe how one may use a magnetic field to create a magnetic monopole in a Bose-Einstein condensed atomic gas. This paper was also highlighted in Physics, so there is nothing left for me to write about.

The only thing I wonder is what happens if one uses molecular Bose condensate, or a subcritical, but non-condensed quantum gas, and uses the laser field instead of the magnetic one? Or, even worse, uses an electric field to manipulate condensed polar molecules?

Also, a few months ago I came across a paper, where some graphene-based system was proposed to "simulate" a Dirac monopole. But, unfortunately, I cannot remember the link...

Monodromy in a classical system experimentally observed

A few days ago an interesting preprint was published on the arXive: "Experimental demonstration of classical Hamiltonian monodromy in the 1:1:2 resonant elastic pendulum" by Fitch et al. Interesting, the contributors, like for instance Heather Lewandowski, are mainly involved in another kind of business: cold molecules. However, in this piece of work they indeed perform experiments with a classical pendulum, and find some monodromy there (that's probably a bad idea to put a link to something I completely don't understand).

In quantum mechanics monodromy occurs when there are no good quantum numbers. For instance, when a linear molecule is rotating in a free space, the rotational angular momentum J is conserved, and so is its projection to the Z-axis, M. When we turn on an electric field, the space isn't isotropic anymore, and the angular momentum J is not conserved, while its projection to the field direction, M, is. Then, if another field is applied, noncollinear with the first one, no good quantum numbers will remain to describe the molecule. In such a case there are no "good" ways to label molecular states. Also, a strange phenomenon, called "the label switching" appears: labels of states depend on in which order you turn on two noncollinear fields.

When everything goes bad monodromy appears on the scene: this is the case for a molecule in two tilted fields (article with preprint).

Coming back to preprint by Fitch et al, which will appear in PRL soon: this is the first observation of monodromy in a classical system ever. And it's a pleasure to read such a good-written article by guys, usually working in the extreme quantum regime.

Is PRL Too Large to Have an ‘‘Impact’’?

Recently there was published a PRL Editorial with such a title. The main message is that only a small fraction of Letters are really highly cited - if one publishes them separately, they will have an impact factor of about 20, while PRL's number is about 7. So, this might be a good idea to reject more papers and accept only revolutionary contributions. However, the problem is that nobody can actually predict how many times a given article will be cited in a few years...

A new way for science popularization

Galileo's finger goes on display in Italy - an article by Daily Telegraph:

"The digit will be part of a landmark exhibition marking the 400th anniversary of his first observations of the skies...The finger was removed when the astronomer's body when it was exhumed from his unconsecrated grave and transferred to a mausoleum in a Florentine church in 1737. It is usually on display at Florence's Museum of the History of Science."

Do you really want to become a great scientist?

Why one needs peer review?

A few days ago Michael Nielsen published an excellent post "Three myths about scientific peer review". Briefly, in the nonscientific (and sometimes in the scientific) community it is usually supposed that:

i) Peer review system was used since very long time ago. Actually, it was not. For instance, Albert Einstein, while living in Germany, was not used to "independent referees" - in such journals as Zeitschrift für Physik the decision "whether to publish a paper or not" was always made by editors. And, as far as I know, before WWII this journal was considered as much better place to publish than Physical Review. After moving to the US, Einstein had withdrew one of his contributions from the Physical Review, because he "has not authorized the editor to show it to specialists before it is printed". I wrote a little post about this story before.

ii) It is reliable, in other words "it nearly always picks up errors, is a very accurate gauge of quality, and rarely suppresses innovation". Of course, no one can predict the future, and say which piece of work will be a "citation classic" in ten years. Furthermore, there is probably no way to discuss the reliability of peer review since we simply don't know how many revolutionary papers were never published (or were, but in some obscure journals) due to negative referee reports.

and

iii) It can show what is right and what is wrong in science. This is also not true, because it is impossible to check all math in the manusript, redo computations, not to mention repeating experimental results.

The post of Michael was followed by interesting comments of Daniel Lemire, "The purpose of peer review", induced by another comment of Peter Turney to Michael's post: "I’m sympathetic to much of what you’re saying, but, on the other hand, I know that peer review has immensely improved many of my own papers."

Being nothing but graduate student, I absolutely agree with Daniel and Peter: at least two from three papers, written during the first year of my PhD, were substantially improved after referee's comments. Apart from submitting  the papers, we have always sent preprints to some good friends from our field - always getting positive feedback (some of them may be the referees in the same time, but this we don't know).

In my opinion, the fact of peer review doesn't mean that the article is reliable, correct or "interesting to a wide community of scientists" (as it should be e.g. for Nature and Phys. Rev. Lett.). But, the review process is some kind of necessary (but not the sufficient!) condition for paper to be read and cited in the long-time future. After publication the scientific community will make it clear, whether such a condition was actually sufficient - there will be a lot of readers  and time for it, much more than two referees having three weeks to submit a report.

Of course, no one can read all journals in his field, even if the field is small enough. Let alone that articles show what was done about one year ago, but not now. Almost no one is actually reading journals - conferences and arXive give a perfect taste of what is going on. But if we come across an arXive preprint dated back to 2007 without any journal reference - this looks strange, doesn't it?

And last, but not least, it seems that reviewing good papers is an excellent way to learn how to write good papers.

How much force does it take to stab somebody to death?

Here is a review of an absolutely crazy arXiv preprint:

"A number of groups have attempted to measure the forces necessary to penetrate skin but the results are difficult to apply to murder cases because of the sheer range of factors at work. The type and sharpness of the knife; the angle and speed at which it strikes; the strength of skin which varies with the age of the victim and the area of body involved; these are just a few of parameters that need to be taken into account.
...
They [the authors, by Misha] have developed a machine that measures the force required to penetrate skin–either the animal kind or an artificial human skin made of polyurethane, foam and soap. The surprise they’ve found is that the same knives from the same manufacturer can differ wildly in sharpness. And the force required for these knives to penetrate the skin can differ by more than 100 per cent."

This is definitely the strangest preprint I've ever seen...

A popular article about Zeno effect

Some time ago we were asked to write a little popular article in the Oktober issue of the Czech journal Chemické Listy, in occasion to the 80th birthday of Prof. Rudolf Zahradnik. For a long time he was a president of Czech academy of sciences, and about ten years ago was even asked to be a Czech president candidate, but refused.

Finally, we came up with an article about quantum Zeno effect, called "Kvantový Zenonův jev aneb co nesejde z oči, nezestárne", which sounds in English as "Quantum Zeno effect, or who's kept in sight, won't age".

This is the first article by myself, which I do not really understand, because it was translated and published in Czech.

Links for 19.10.2008

Useful:

• Springer Online Reference Works - online encyclopedia of math
• Advanced physics forums

Interesting:

• Why LaTeX is like Latin - by Paul Goldberg. "LaTeX, like Latin, does not prevent one from writing down a statement that is incorrect. ... But it does help to prevent vagueness."
• Essay: Fifty Years of Atomic, Molecular and Optical Physics in Physical Review Letters - by Serge Haroche.
• The complete work of Charles Darwin online
• Old scientists never clean out their refrigerators - the story of the Miller-Urey experiment
• Website of Michio Kaku, and his opinion about the last Nobel Prize.

Blogs:

• How you can save the world - an interesting blog, written by many well-known contributors, string theorist Michio Kaku among them.

Funny:

• Iran minister admits holding fake Oxford degree
  
• 'Punch drunk' pony rescued from swimming pool
  

Nobel Prize in physics 2008

I am completely ignorant in the field of particle physics, but here is an excellent essay about the science behind the today's prize.

The 2008 Ig Nobel Prize Winners

Since I'm a physicist, I present physics the first:

PHYSICS PRIZE. Dorian Raymer of the Ocean Observatories Initiative at Scripps Institution of Oceanography, USA, and Douglas Smith of the University of California, San Diego, USA, for proving mathematically that heaps of string or hair or almost anything else will inevitably tangle themselves up in knots.

But, my favorite one is a chemical one:

CHEMISTRY PRIZE. Sharee A. Umpierre of the University of Puerto Rico, Joseph A. Hill of The Fertility Centers of New England (USA), Deborah J. Anderson of Boston University School of Medicine and Harvard Medical School (USA), for discovering that Coca-Cola is an effective spermicide, and to Chuang-Ye Hong of Taipei Medical University (Taiwan), C.C. Shieh, P. Wu, and B.N. Chiang (all of Taiwan) for discovering that it is not.

here are other prizes

Fermat's last theorem

I was often thinking about "whether Fermat really had a proof of his famous theorem":

Theorem. There are no positive integers x, y, z, and n > 2 such that x^n + y^n = z^n.

Today I found an answer in the mathematical FAQ:

"Did Fermat prove this theorem? No he did not. Fermat claimed to have found a proof of the theorem at an early stage in his career. Much later he spent time and effort proving the cases n = 4 and n = 5. Had he had a proof to his theorem earlier, there would have been no need for him to study specific cases."

This is followed by an interesting discussion about different mistakes that Fermat may have done (see section 3.1.4 of FAQ).

But, anyway, Pierre de Fermat never had his theorem proven.

Why is mercury liquid?

The answer is clearly presented here. I find very interesting that mercury does not crystallizes at the room temperature not only due to the filled atomic shells (the Hg configuration is [Xe] 4f14 5d10 6s2), but also because of relativistic effects, which decrease the radius of the 6s orbital.

Mercury is a liquid at room temperature because the "relativistic contraction" of its atomic orbitals makes it behave chemically almost like a noble gas, not wanting to share electrons with other atoms, even other mercury atoms! Note that mercury is monatomic in the gas phase, just like a noble gas. Of course this should not be pushed too far; mercury is not a noble gas. There are enough outer-electron interactions for mercury to remain a liquid (radon, 22 amu heavier, is a gas), to conduct electricity, and to participate in ordinary chemical reactions...

Brian Green about string theory

No, this is not another rap (take a look at his hands, yo). These are very clear and understandable explanations of "what the string theory is" by Brian Greene:

via Greg Laden's blog

Astrobiology rap

not so cool as the one about LHC, but anyway



via Dynamics of cats.

LHC Rap

The best popular lecture I have ever seen...

Knol

Сегодня Google Scholar известил меня о том, что появился новый проект от Google, называется Knol. Кноль - это единица знаний, от слова knowledge. В общем, каждый желающий приглашается туда написать статью о том, что он знает. На данный момент, я не совсем понимаю цель этого проекта... Разве что, при должном пиаре, он может составить альтернативу Википедии. Отличия, безусловно, есть: отправить статью может кто угодно, редактировать её просто так нельзя, но можно послать еще одну, от своего имени. Короче говоря, время покажет.

Paul Richard Halmos «How to write mathematics»

Русский перевод статьи изветсного математика Пауля Халмоша "Как писать математические тексты".

Нашел через Словоманию.