Two atoms meet in the street...

I've heard a funny anecdote in one of the recent Car Talk shows:

Two atoms meet in the street. One says:
- I feel myself so bad... It looks like I've lost an electron.
- Are you sure?
- Yes, I'm positive!

Sorry guys who already know it.

Conference proceedings vs articles in Computer Science

It came as a surprise to me that in Computer Science conference proceedings are more prestigious than peer-reviewed articles (see comments to this post). Furthermore, people never publish papers in journals, considering those to be a waste of time.

This is an opposite of what is going on in physics/chemistry/biology, so I asked Daniel Lemire on twitter whether that is true. Daniel explained to me that before the on-line era, the publication cycle was way too long for such a fast-developing field like Computer Science. Therefore journals traditionally don't have so much authority as conference proceedings, which are much faster for science communication.

Angry and calm faces

If you look at this image, the face on the left looks like an angry old man, while the one on the right looks like a calm woman.

Step back from your computer five or ten feet, and you will see that the images seem to change places!

The thing is that coarse features and fine features are distinguished differently at different distances.When both sets of features are blended into one image, the mind sees the different feature sets, depending on the distance of the viewer.

Here is the original post. There is also some real research done on this.

Thanks to Valera Yundin for the link.

Bose-Einstein condensation of calcium achieved

Scientists from Physikalisch-Technische Bundesanstalt (German national metrology institute) in Braunsweig recently obtained a Bose-Einstein condensate from about 20 000 calcium atoms. This is the first successful attempt to condense alkaline earth species.

Up to now, Bose-condensation was achieved in atomic gases of a number of alkalis (Li, Na, K, Rb, and Cs), and also of ytterbium, chromium, hydrogen, and metastable helium.

Peer-Review 2.0

A new kind of peer-review was featured in a recent post in Nature blog.

Commenting on a blog post about something completely different, a guy nicknamed Liquidcarbon drew attention to an article in Journal of the American Chemical Society, that he found to be completely odd. After less than 24 hours after his "WTF is going on there?", the experiments were reproduced showing results, different from those of the original paper.

Being quite far from pure chemistry, I can not judge whether the conclusions of the article and those of bloggers are correct. But, anyway, here is a good example of how science will probably look like in the future - now we call this Science 2.0.

Do you read all the papers you cite?

If the answer is "Yes", it is most likely a lie.

Quite a while ago, Mikhail Simkin and Vwani Roychowdhury from UCLA published a preprint about this, "Read before you cite!". The authors present a statistical approach to estimate how many people who cited a paper, had actually read it. Here "to read" means "to take at least a brief look" or even "to download a copy of the paper".

The main idea of the method is to analyze... the number of misprints in the list of references. For instance, if some paper is cited by a bunch of different articles, with the same misprint in the page numbers, most likely the authors just copy-pasted a reference from each other's work, without even downloading the article. As for me, I faced with this a few times.

The final estimate obtained by Simkin and Roychowdhury is that about 80% of the citers don't read (say, never downloaded) the paper they cite.

Thanks to Daniel Lemire for sharing the link on Twitter!

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...

Links for 12.07.09

1) Ten Creative Re-Invention Of The Light Bulb

2) Scriblink - the online whiteboard. You can draw anything you wish and then send off a link. It is possible to discuss stuff by drawing on the same board in real time. You can also use TeX.

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.

Efimov states in biology

About forty years ago, Soviet physicist Vitaliy Efimov predicted the existence of some special three-body quantum states. A particular feature of those is that the two-body state (like a diatomic molecule) cannot be formed: the interparticle interaction is still too weak for this. However, a very weakly-bound trimer is possible, due to three-body interaction. Nowadays Vitaliy is a part of nuclear theory group at University of Washington.

Efimov states were experimentally observed by Rudi Grimm's group, only 35 years after the theoretical predictions, here is a paper and a preprint (if you are not a Nature subscriber). You may also wish to take a look at their group page about Efimov states, with links to original Vitaliy's papers (click to "Evidence for Efimov quantum states in an ultracold gas of Cs atoms" highlights from March 15, 2006).

I think there might be some Efimov states in biology, either. For instance, take a sloth bear:

It is also known as a "lip bear", and has long lips indeed:

As for myself, I would never believe that such a creature appeared during a usual Darwinistic evolution. I suppose it to be rather an Efimov state of brown bear, tapir and echidna, with no two-body states possible:

+

+

=

However, this kind of proposal is still to be tested experimentally...

Four brothers... from the same institute

via Igor Ivanov's blog. A link to the original article.

WW II in color

Here you can find a lot of colored and black-and-white photos of the second world war, from both sides of the conflict. Extremely interesting.

Links for 29.04.09

1) A theoretical physics FAQ by Arnold Neumaier 

2) A book by Arnold Neumaier "Classical and Quantum Mechanics via Lie algebras" is available here. It will be published soon by Cambridge University Press.

3) Motion Mountain, The Free Physics Textbook by Christoph Shiller

Faraday Discussions

Last week I participated in Faraday Discussion 142: Cold and Ultracold Molecules, presenting a poster there. For those of you who don't know, what Faraday Discussions are I will describe it in two words.

The conference is organized by the Royal Society of Chemistry, it has a centennial history and takes place a few times a year nowadays. This time it was at Durham University, UK. Faraday Discussions are not "real conferences" with long plenary talks and short student's contributions. Actually, they are nothing but... discussions.

People submit their abstracts well ahead of time, about one year before the conference. The best abstracts are selected for oral presentations and the lucky guys are asked to submit full-length papers about their work. Then, after the peer-review process, preprints are sent to all participants, who are expected to read them carefully before coming to the place.

Talks at the discussions are limited by only 5 minutes - it should be just a "reminder" to people, who already read the preprints. This rule is quite strict: there is a special guy sitting next to traffic lights, which are green when you start a presentation. After four minutes the lights are switched to yellow, and they turn out to be red after five minutes. At this point you are interrupted at half a sentence - no other way around.

Presentations are scheduled in such a way that they are more or less about the same subject within a single session. So, a few five-minutes talks are given one after another. Then the discussion begins - the most interesting part, taking about one hour. People ask a lot questions, both technical and general ones, but "comments" are also possible. The latter are short presentations, also restricted by the traffic lights, which are relevant to the main contributions. For instance, a theorist, who came up with some explanation after having read the experimental preprint, can briefly describe his idea and show some slides with results.

All questions, answers and comments (along with the papers themselves) are then collected and published a few months later as a volume of Faraday Discussions, a journal having quite a good impact factor, about 5.0 these days.

I find this kind of format to be much more efficient, than usual conferences, where people may have no questions simply because they haven't got the idea of the work during the talk.

On my webpage you may find my poster as well as two preprints about our project (0903.0811, 0904.0567).

arXiv endorsement

Many years ago, the arXive was successfully working without any peer-review. But at some point, they started to get a lot of really odd submissions from science freaks, about new "theories of everything", violation of general relativity theory and other things of this sort.

Therefore, an "endorsement" mechanism was introduced, so anyone who submitted a few papers to archive can recommend a preprint of a new guy to be accepted. This is not a true peer-review, the endorser is only expected to check whether the preprint is about science in general, like it doesn't pretend to prove how stupid Einstein was. Not all the archive sections require endorsement - I guess, only fundamental topics, like high-energy physics do.

I'm an endorser for the atomic physics and chemical physics sections, which is quite useless, since no endorsement is needed there. However, today I've got the first "can you endorse me, please?" kind of message, and, yes, this is one from a science freak. I don't know what to do, I must confess. :-)

My scientific webpage

Following the advice of my supervisor, I've finally got a scientific webpage. That's it, essentially. :-)

Chemical Physics vs Physical Chemistry

At one of the last conferences I've attended, we've got a nice informal discussion about a usual subject "what is the difference between physical chemistry and chemical physics". We concluded that there might be a following way to distinguish between those. If you measure/calculate the reaction cross section, you are definitely a chemical physicist. But, if you multiply the cross section by the velocity, and therefore measure/calculate the reaction rate, you belong to the physical chemistry community. What is your opinion on that?

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 terrific lectures course

If you work in AMO physics and you are out of reading, here is an excellent course in modern atomic and optical physics by Misha Lukin (Harvard) - the first link here.

Yuja Wang plays the Flight of the Bumble-Bee

You have to see that:

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?

Mathematical Tools for Physics

Yesterday I came across a wonderful lecture notes of math methods in physics for undergrads, namely "Mathematical Tools for Physics" by James Nearing. There is a lot of simple math in there, but with really good explanations where in physics this may be of use. Also James gives a lot of funny math tricks.

I wish I had such a lecture course while studying in university.

Solving problems: theorists vs. experimentalists

A problem:

How they solve it:

via Talk like a physicist

A new book on QM

A very, very strange book appeared in arxive a few days ago: "Quantum Mechanics" by Hitoshi Kitada (University of Tokyo).

Here are the names of some chapters: "Quantum Mechanical Time Contradicts The Uncertainty Principle", "Definition of local time", "Motion Inside a Local System", "Principle of General Relativity", "Inconsistency of Mathematics?", "Stationary Universe", "Existence of Local Motion", "Local time exists", and so on.

Hm, "stationary universe" in the QM course... Let's take a look at this chapter:

"By nature what is called the universe must be a closed universe, within which is all. We will characterize it by a certain quantum-mechanical condition.We consider a metatheory of a formal set theory S. We name this metatheory M_S, indicating that it is a Meta-theory of S as well as a Meta-Scientific theory as Ronald Swan [46] refers to. The following arguments are all made in M_S....The class φ is the first world, the Universe, which is completely chaotic. In other words, φ is “absolute inconsistent self-identity” in the sense of Kitarou Nishida [41], whose meaning was later clarified by Ronald Swan [46] in the form stated above. In this clarification, φ can be thought “absolute nothingness” in Hegel’s sense."

Oh mein Gott, "in Hegel's sense"... I wonder whether physics students at Tokyo university have to pass an exam on this.

Phil Anderson on computations

Here is a quote from a Nobel Lecture of famous condensed-matter theorist Phil Anderson:

"...Very often such, a simplified model throws more light on the real workings of nature than any number of “ab initio” calculations of individual situations, which even where correct often contain so much detail as to conceal rather than reveal reality. It can be a disadvantage rather than an advantage to be able to compute or to measure too accurately, since often what one measures or computes is irrelevant in terms of mechanism. After all, the perfect computation simply reproduces Nature, does not explain her."

While Anderson gave his lecture in 1977, this seems to be even more relevant nowadays.

Another theorist, Phil Bunker, while giving talks, often describes somebody's work as "...these guys with small brains and big computers!"

Yeah, well, I'm gonna go make my own ranking, with blackjack and hookers!

... In fact, forget the ranking!

This is perhaps what the Futurama's Bender would say, while working in Moscow State University. 

In 2008 MSU took the 70th place in the World's university ranking held by Shanghai university. In 2007 and 2006 these were 76 and 70 places. This is actually not bad. For instance, MSU was ranked as 186th university in some other ratings.

What one can do with it? It's kind of simple. The university president decided to make his own ranking, and now MSU has the the 5th place (Russian). The lucky guys that took first four places will be announced this month. 

That's probably a good way to push science and encourage scientists...

Doing physics as states superposition

(via Shores of the Dirac Sea)

But what the f(t) function looks like? On my opinion, in the vicinity of deadline it may be estimated as

f(t)=Floor(0.5*Cos(t^2) + 1),

with Floor(x) giving the greatest integer less or equal to x. 

Are they some less rough approximations?

Links for 01.02.09

1) A calender with naked French politicians - by Roland Hours.

2) Is massively collaborative mathematics possible? - Gowers's weblog.

3) Thousands of video lectures from the world's top scholars - a terrific project.

4) Lab-initio, a lot of funny science pictures.

5) Italian history of physics archive - some old scientific journals are accessible after free registration.

6) Leningrad Siege: Now and then, from English Russia - shows how Saint Petersbourg waw looking during WWII.

Old books with Google

I never mentioned that apart from partial preview, Google books offers some full-text books to read and download. For, instance, here are books in math, which are out of copyright and can be read for free. Of course, most of them are old, and even ancient as, for instance, "Arithmetical Tables Fitted to the Capacity of Such as are Unskilled in the Art of Numbers" by Henry Walrond, published in 1663. The book describes how to work with numbers, add and subtract them. 

What is interesting for me is the old English, this book is written in. Previously I thought that it will be extremely hard for me to read such old printings. But, surprisingly enough, there is no big difference with the modern language. There are some funny words there, for instance "shew" and "your self", instead of "show" and "yourself".

I wonder why Google finds many more copyright-free books in mathematics, than in physics or in chemistry...

Starcraft Course in Berkeley

UC Berkeley students can now take a course in Starcraft game. 

"This course will go in-depth in the theory of how war is conducted within the confines of the game Starcraft. There will be lecture on various aspects of the game, from the viewpoint of pure theory to the more computational aspects of how exactly battles are conducted. Calculus and Differential Equations are highly recommended for full understanding of the course. Furthermore, the class will take the theoretical into the practical world by analyzing games and replays to reinforce decision-making skills and advanced Starcraft theory." 

[link]

Yes, calculus and differential equations are needed. I guess the same phrase appears in the Introduction chapter of quantum mechanics books.

UPD In one of Taiwanese universities there is a porn course. I wonder whether differential equations are still recommended...