MIT students study the effectiveness of aluminium foil helmets

A relatively old, but extremely funny article:

Among a fringe community of paranoids, aluminum helmets serve as the protective measure of choice against invasive radio signals. We investigate the efficacy of three aluminum helmet designs on a sample group of four individuals. Using a $250,000 network analyser, we find that although on average all helmets attenuate invasive radio frequencies in either directions (either emanating from an outside source, or emanating from the cranium of the subject), certain frequencies are in fact greatly amplified. These amplified frequencies coincide with radio bands reserved for government use according to the Federal Communication Commission (FCC). Statistical evidence suggests the use of helmets may in fact enhance the government's invasive abilities. We speculate that the government may in fact have started the helmet craze for this reason.

X-ray from the Scotch tape

A funny article in Nature:

Relative motion between two contacting surfaces can produce visible light, called triboluminescence. This concentration of diffuse mechanical energy into electromagnetic radiation has previously been observed to extend even to X-ray energies. Here we report that peeling common adhesive tape in a moderate vacuum produces radio and visible emission, along with nanosecond, 100-mW X-ray pulses that are correlated with stick–slip peeling events. For the observed 15-keV peak in X-ray energy, various models give a competing picture of the discharge process, with the length of the gap between the separating faces of the tape being 30 or 300 m at the moment of emission. The intensity of X-ray triboluminescence allowed us to use it as a source for X-ray imaging. The limits on energies and flash widths that can be achieved are beyond current theories of tribology.

Happy Mole Day!

It turned out that today (10/23 in American notation) is a Mole Day...

Scholarpedia

Surprisingly enough there is a peer-reviewed alternative to Wikipedia, called Scholarpedia. The authors pretend that 

"...Scholarpedia articles could be cited, articles are not frozen and outdated, but dynamic, subject to an ongoing process of improvement moderated by their curators."

So it is supposed to be better than Wiki, due to the peer-review system, and better than any printed issues, because they cannot be changed.

I wonder whether Scholarpedia will really become a source of "articles that could be cited".

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
  

The most specialized journal I ever seen

Today I came across a journal called "Platinum metals review", which is present in our labrary,but isn't indexed by Web of Science, though.

The simpler the better

Abstruse Goose

The crisis and life

www.phdcomics.com

Links for 12.10.08

• Chemical Portal - an excellent collection of useful tools and tables
  
• The collapse of peer-review - from the economist's point of view
• What's Interesting About AMO Physics - by Chad Orzel
  
• APS now leaves copyright with authors for derivative works - "When you submit an article to an APS journal, we ask you to sign our copyright form. It transfers copyright for the article to APS, but keeps certain rights for you, the author. We have recently changed the form to add the right to make ‘‘derivative works’’ that reuse parts of the article in a new work."

For this day

Echte Männer essen keinen Honig, sie kauen Bienen.

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 teacher's day

Today is a Teacher's day in Russia (also in Pakistan and Philippines :-), and www.google.ru looks like this:

The date is chosen to coincide with the World Teacher's Day, defined by UNESCO.

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

Brown sharpie

Another funny mathematical cartoon

A terrific Nature cover

I wonder whether this is an "accidental degeneracy", or there is some hidden symmetry in it...

Bloggers given new Ten Commandments by church leaders

Christian bloggers have been given a new set of 'Ten Commandments' aimed at delivering them from the temptations of online arguments. Here it is:

1) You shall not put your blog before your integrity.
2) You shall not make an idol of your blog.
3) You shall not misuse your screen name by using your anonymity to sin.
4) Remember the Sabbath day by taking one day off a week from your blog.
5) Honour your fellow-bloggers above yourselves and do not give undue significance to their mistakes.
6) You shall not murder someone else's honour, reputation or feelings.
7) You shall not use the web to commit or permit adultery in your mind.
8) You shall not steal another person's content.
9) You shall not give false testimony against your fellow-blogger.
10) You shall not covet your neighbour's blog ranking. Be content with your own content.

Links for 28.09.08

• Sergey Brin's blog
• Survivor: theoretical physics - some thoughts about career.
• How long should an astronomical paper be to increase its Impact? - an interesting preprint.

Links for 14.09.08

Scientific:

• Webcam at LHC - want to know what's going on there?
• Frequently asked questions in mathematics - by Alex López-Ortiz.
• Mathematical constants - by Steven R. Finch.
• NIST digital library of mathematical functions
• Theoretical computer science cheat sheet - a .pdf file there.

Interesting:

• Google launches the digitalization of old papers
• Has the Large Hadron Collider destroyed the earth yet?
  

The Monte-Carlo method

I was actually not aware of the fact that the Monte-Carlo method of integration was proposed by Stan Ulam working on Manhattan project at Los Alamos. I also like his aphorism, which I came across of here:

"My late friend Stan Ulam used to remark that his life was sharply divided into two halves. In the first half, he was always the youngest person in the group; in the second half, he was always the oldest. There was no transitional period."

Secret History of Quantum Physics

An interesting post by Chad Orzel, about the great discoveries made during vacations:

"Erwin Schrödinger famously discovered the equation that bears his name while on a skiing holiday in 1925. He was accompanied on this vacation by one of his many girlfriends, but which of them went on the fateful trip has been lost to history-- Schrödinger kept exceedingly detailed diaries, but the volume covering the relevant period has been lost."

I'm eager to know, who was his girlfriend...

Ten Lessons I wish I had been Taught

I came across these advices of Gian-Carlo Rota in the blog of Alexandre Borovik. Among them there is the following one:

"6) Do not worry about your mistakes.
Once more let me begin with Hilbert. When the Germans were planning to publish Hilbert’s collected papers and to present him with a set on the occasion of one of his later birthdays, they realized that they could not publish the papers in their original versions because they were full of errors, some of them quite serious. Thereupon they hired a young unemployed mathematician, Olga Taussky-Todd, to go over Hilbert’s papers and correct all mistakes. Olga labored for three years; it turned out that all mistake scould be corrected without any major changes in the statement of the theorems. There was one exception, a paper Hilbert wrote in his old age, which could not be fixed; it was a purported proof of the continuum hypothesis, you will find it in a volume of the Mathematische Annalen of the early thirties. At last, on Hilbert’s birthday, a freshly printed set of Hilbert’s collected papers was presented to the Geheimrat. Hilbert leafed through them carefully and did not notice anything."

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.

Wolfram support

I was surprised by fast and friendly support that Wolfram offers to Mathematica users. The last two days I was bothering with a problem, which occurs when you try to calculate an alternating sum consisting of big numbers - the precision was not high enough and I always obtained a "noisy" curve instead of the smooth one. I played with accuracy and precision, but nothing helped. Finally, I've sent my notebook to Wolfram support, and have got an answer within a few hours, with a correct notebook attached. Now it seems to work - it is a bit tricky, though. 

The LHC switches on this morning

Sincerely, I don't want to contribute in the worldwide discussion about the "black hole consisting of antimatter" (c) which will destroy the Universe, but there is a nice picture from Google today:

How to learn any language?

Some time ago I came across a very interesting website by a Swiss amateur linguist François Micheloud. He presents an interesting table for those people who want to learn a foreign language, but don't know from which one to start (or which should be the next). François compares difficulty, popularity, transparency, the number of countries speaking the language etc. For instance he rates Russian to be the easiest languages among the "languages usually considered as hard".

Links for 07.09.2008

Scientific:

• Free mathematics textbooks online
• Abramowitz and Stegun: Handbook of Mathematical Functions - an online version of famous reference.
• Data paparazzi - about writing papers based on a snapshot of a data slide made at a conference.
• How to be a good teaching assistant - some advices
• 20 Things I Have Learned as a College Professor
• Why Assistant Professors Should Earn More Than the Tenured
• Do numbers have personalities? - The Herald article about John Baez' opinion on this.
• Plush subatomic particles - terrific toys for particle physicists, there is a Higgs boson and dark matter.
• Quantum minigolf - essentially the same thing as minigolf, but with quantum particles
• Physicists periodic table - by Timmothy Stowe.

Useful stuff:

• Scribd - a "YouTube for documents", supports a variety of formats.
• Chrome - a new browser from Google. Only for Windows yet.
• FriendFeed - probably everyone knows this, but I came across it only today. Using friendfeed.com you can share everything you produce in one place. It supports blog, youtube, google reader, picasa, and probably everything else you may need. My account there is lemeshko.

Other:

• Urban Legends - an interesting collection.
• Deadjournal - a livejournal for emokids.

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...

Citations for 07.09.2008

Probably it might be a good idea to make something like bash.org, but for aphorisms and interesting citations... Here there are a few I came across this week:

• Young man, in mathematics you don't understand things. You just get used to them. John von Neumann

• There are three rules for writing the novel. Unfortunately, no one knows what they are.  W. Somerset Maugham

•  Teach the Students You Have - not the ones you wish you had. If you get annoyed at students for being insufficiently prepared, or not as smart as you, you'll become a grumpy old fart, just like some of the lousy teachers you had. John Baez

The Most Alien-Looking Place on Earth

An article about a unique island, with a lot of pictures...

Imagine waking up on the Socotra Island and taking a good look around you (let's say your buddies pulled a prank on you and delivered you there, and lets also assume that you don't have any hangover from abuse of any substances). After a yelp of disbelief, you'd be inclined to think you were transported to another planet - or traveled to another era of Earth's history.

The second would be closer to the truth for this island, which is part of a group of 4 islands, has been geographically isolated from mainland Africa for the last 6 or 7 million years. Like the Galapagos Islands, this island is teeming with 700 endemic species of flora and fauna, a full 1/3 of which are found nowhere else on Earth.