Some stuff for 05.07.2012

(1) Stephen Hawking's party for time-travellers. I wonder whether it was organized in order to drag attention from the recent $100 bet he lost :-)

(2) Three (!) stories in the last Nature issue about the collapse of Spanish science happening right now: [1], [2], [3]

Take care,

Misha

Two most useful papers of this week :-)

(1) D. Kobak, S. Shpilkin, M. S. Pshenichnikov, "Statistical anomalies in 2011-2012 Russian elections revealed by 2D correlation analysis", arXiv:1205.0741

A solid scientific base for what basically everyone knows already :-) Also, unlike previous analyses appearing on the internet, this one is in English, so everyone can understand it and spread the word.

(2) H. C. Mayer, R. Krechetnikov, "Walking with coffee: Why does it spill?", Phys. Rev. E 85, 046117 (2012). There is also a popular synopsis about it.

I was used to think that spilling coffee while walking (and then making innocent eyes and speeding up) was my own problem, because I basically break everything I touch. This article made me feel normal, just as everyone else. Finally, there is a scientific base for spilling coffee!

Take care,

Misha

Some links for 25.03.12

(1) Picture-hanging puzzles by Demaine and coauthors

(2) What the referee reports on some citation classics might have looked like? (computer science)

(3) Why do physicists need a salary raise?


Take care,

Misha

Vavilov, Cherenkov, and credit for discoveries

We all know that accelerated charged particles emit light - that's how modern high-intensity light sources, synchrotrons, function. Interestingly, uniformly moving particles can emit light too.

The idea goes back to the 1904 Sommerfeld's paper, where he studied the motion of charged particles in a vacuum, and demonstrated that particles flying faster than the speed of light emit radiation even when moving uniformly [1]. Of course, the special relativity theory that appeared next year, rendered Sommerfeld's discovery just a funny mathematical result that has nothing to do with reality, since according to the special relativity no particle can move faster than light in a vacuum.

It's worth noting that the velocity restrictions imposed by the special relativity apply only to a single particle (a group velocity of a bunch of particles can be anything) moving in a vacuum (the speed of light in a medium is much smaller than in a vacuum and particles can move faster than that). However, it took more than 30 years to generalize the Sommerfeld idea to the case of charged particles propagating through a material.

Pavel Cherenkov was pursuing a PhD under Sergey Vavilov, a brother of a famous geneticist Nikolai Vavilov (who was imprisoned and eventually killed by the Soviet regime). Cherenkov was studying the luminescence of uranium salts in solutions irradiated by gamma-rays, and was quite surprised to see the "luminescence" of a pure liquid (sulfuric acid it was), with no salts added. Actually, he was convinced that his PhD work was completely ruined [2].

And it was Vavilov who suggested that this radiation was not luminescence but something completely new, and encouraged Cherenkov to continue the measurements. Indeed, very soon Igor Tamm and Ilya Frank developed a theory for the effect, showing that the radiation is emitted by electrons propagating faster than the speed of light in this particular solution. In 1958 Cherenkov, Tamm, and Frank shared a Nobel Prize for this discovery (unfortunately, without Vavilov who deceased in 1951).

Although Russians call it the "Vavilov-Cherenkov effect", it seems that the name of Vavilov is omitted in the rest of the world where people simply refer to the "Cherenkov Radiation". Why do they?

The funny thing is that immediately after the discovery Vavilov (himself) wrote a paper and submitted it to Nature, where it was rejected (!), and then to Physical Review. This paper had a single author - Cherenkov [3].

I wonder whether such an extreme academic generosity would be possible nowadays :-)

Take care,

Misha

[1] A. Sommerfeld, Göttingen Nachrichten 9, 363 (1904); 201 (1905)

[2] V. L. Ginsburg "About science and about myself" (2001)

[3] P. A. Čerenkov, Phys. Rev. 52, 378 (1937)

The swastikas

Researchers have designed the first emitter of circularly polarized light made from a stand-alone semiconductor device:

"Giving Light a Spin", Physical Review Focus

I doubt that a paper containing nazi symbols would be published in Germany nowadays :-)

Misha

Happy New Year!

We, physicists, will never understand the logic of chemists. But, che fare - che fare, the forthcoming year is going to be yours:

Be happy, and remember that if two cesium atoms are bound together by only 0.000000004 kJ/mol - we call it "the Cs₂ molecule". Because... this is a molecule.  :-P


Take care,

Misha

A nice title

It's an art to write a title in such a way that no one even needs to read an article:

"In general, the less degeneracy the less transition. A principle for time‐dependent Hamiltonian systems in quantum mechanics", H. Gingold, J. Math. Phys. 28, 2400 (1987).

Misha

Physics Nobel Prize 2010

I was about to make a joke that the third part of the Nobel Prize should have been awarded to Andre Geim's hamster Tisha, but I better don't :-)

Misha

The scientist whose rudeness cost him a Nobel prize

The Nobel week began today, and The Guardian published a nice article about Fred Hoyle, the scientist who should have gotten a Nobel prize, but never did.

Misha

Brian Josephson

It turned out that Brian Josephson, who received the 1973 Nobel prize in Physics for prediction of the Josephson effect, is an active protagonist of cold fusion and parapsychology.

That's funny.

Take care,

Misha

Benford's law

In 1881 the American astronomer Simon Newcomb noticed that in books of logarithm tables first pages (logarithms of numbers starting with 1) are much more worn than others. This means that  people look up numbers starting with 1 more often than higher ones, which is a pretty weird result.

This effect was rediscovered in 1938 by Frank Benford, who checked it for different real data sets, and it's called Benford's law since then.

The thing is that such a distribution of numbers arises if their logarithms are distributed uniformly, like it's equally probable to find a value between 10 and 100 and between 100 and 1000. This is the case for most of real world statistics, such as distributions of salaries or building heights.

Well, I'm writing about all that because in 1972 the law was proposed to detect fraud in statistics, because people who make up their data tend to distribute numbers pretty much uniformly. For instance, Benford's law was used as an evidence of falsifications in the 2009 Iranian elections.

Be careful if you're making up your experimental data :-)

Misha

Fritz London about BEC

A funny quote about Bose-Einstein Condensation (BEC) from Fritz London's article (Nature, 1938):


About the same time, Erwin Schrödinger explicitly said that BEC will never be realized experimentally, since required temperatures are way too low (I cannot find an exact quote, please tell me if you came across it somewhere!)

However, in 1995 BEC in dilute atomic gases was observed in a number of labs [1, 2, 3]. In 2001 Eric Cornell, Wolfgang Ketterle and Carl Wieman shared a Nobel prize for that.


Take care,

Misha

Getting married is dangerous

Willis Lamb (discoverer of the Lamb shift) got married three times: to Ursula Schaefer when he was 26, to Bruria Kaufman when he turned 83, and to Elsie Wattson at the age of 94. He deceased the same year, soon after his last marriage. I don't believe that's a coincidence.

Science and religion

It turns out that Georges Lemaître, who proposed the Big Bang Theory (yes, the theory itself, not the sitcom), was not only a scientist, but also a catholic priest. That's funny.

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...

Topless models

As you've understood, I do a little literature search now, and I came across the following (Italian) article:



Is there any chance to figure out what the "topless models" are about? It looks like the Google outcome is about something different.

Hm, probably 50 years ago even Italian prime minister was interested in these topless models... :-)

The shortest article ever

I'm pretty sure I've posted it somewhere about 3-4 years ago, but anyway. This is the shortest article I've ever seen, it was published in Physical Review:


Guys involved in the 'variation of fundamental constants' business always show it in the talks. But I wonder whether it was a joke or not...

Phys. Rev. Lett. half a century ago

Imagine, that you publish an article in Physical Review, then find a mistake and a misprint in it, and decide to submit the correction to Physical Review Letters. Sounds crazy?

This was somehow possible fifty years ago:



(by that time Phys. Rev. Lett. was a section of Phys. Rev.)

But anyway, later there was another, real erratum to this letter to the editor...


Take care,

Misha

How would you know?

Here is a quote from the popular article of Nissan Zeldes "Giulio Racah and theoretical physics in Jerusalem":

"Tensor algebra is the natural mathematical tool for treating angular correlations of successive nuclear radiations, as shown first in [Racah, Rhys. Rev. 84, 910 (1951)] and independently in [Lloyd, Phys. Rev. 85, 904 (1952)]".

Well, that sounds fine. Two scientists were involved in the same kind of business and came up with similar theories about the same time - we see that everywhere in science.

The only problem is that in 1951-52 both Giulio Racah and Stuart Lloyd were working at the same place, Institute for Advanced Study in Princeton. Can one really be sure that the theories were developed independently in such a case?

Hamster Tisha

It turns out that some years ago graphene pioneer Andre Geim published an article co-authored by his hamster Tisha, here it is:

A. K. Geim and H. A. M. S. ter Tisha, "Detection of earth rotation with a diamagnetically levitating gyroscope", Physica B 294-295, 736 (2001)

That's crazy.

via Igor Ivanov's Buzz