Cold Atom

From Le Monde, 30.05.08
by Pierre Le Hir

THE PHYSICS OF COLD ATOMS SHOWS INCREASINGLY PRECISE RESULTS

The interior courtyard of the Paris Observatory contains a number of box-spaces that used to serve as stables and, later, artists' studios. The runners that inhabit them currently are atoms, and the artists masters of light. We are here in the world of the infinitely small, the infinitely cold, the infinitely precise.

On Friday May 30th, the Francilian (Ile-de-France) Institute for Research on Cold Atoms Ifraf, created in 2005 by Claude Cohen-Tannoudji, Nobel Prize in Physics 1997, opened new laboratories on this site, which will permit work in this domaine of excellence within French physics. A very competitive area, where the thirty-two teams working for Ifraf will be up against those of the Massachusetts Institute of Technology (MIT) at Harvard in the United States, of Hanover, in Germany, or of Innsbruck, in Austria. This is because the physics of cold atoms is part of fundamental physics, yet it also has numerous applications in measurement science, in geophysics or in computer science. The basic principle underlying this science is that of slowing down - or what is essentially the same thing, cooling - clouds made up of a few million atoms, in order to precisely measure certain characteristics.

With the aid of laser beams, whose photons create a massive deceleration, it is possible to slow down atoms from a few hundred meters per second to a mere few centimeters per second. Thus caught up in an optical molasses, the atoms are in a super cold-state, a few billionth of a degree above absolute zero (-273,15°C).

One can then measure, for a time period of up to one second - an eternity for a physicist -, phenomena such as the transition between two energy levels in an atom of cesium 133. And thus improve on the accuracy of atomic clocks which calibrate their seconds by matching frequencies with this transition.

COLD MEASUREMENTS IN SPACE

Ever since the advent, in the 1950s, of the first atomic clocks, which have replaced the movements of Earth around the Sun as the standard of time, for example in Global positioning Systems, the precision of such clocks has improved by a factor of ten every ten years. With current systems - cold atom fountains - , these clocks are no more off than one second every 300 million years!

Ifraf scientists are also at work on the Pharao project (Projet d'horloge atomique par refroidissement d'atomes en orbite) which, in 2012 or 2013, should furnish the International Space Station with a new metronome. This would then become, given it's unequaled precision -microgravity permitting slowing down atoms even more -, the universal time referent.

Other projects are aiming for ultra sensitive gravity meters, permitting for example tracking the movement of an earthquake or finding an oil deposit. Or again cryptography or quantum memory.

But cold atoms are also 'tools of choice for fundamental research', points out M. CohenTannoudji. Theoretical physicists, who are having trouble reconciling the laws of general relativity, which hold for large bodies, with those of quantum mechanics, which govern elementary particles, know that their models are imperfect. Greater precision in the observations of atoms thanks to extreme cold could reveal that certain constants, which we have held to be unchanging since the Big Bang, are nothing of the sort. Blowing hot and cold on modern physics, as it were.

Magical Beechtree

THE PONTUS BEECH

This is a story from Britanny about Pontus, a legendary knight and the Beech tree.

In the depths of the forest of Brocéliande, Pontus’ beechtree has grown on the vestiges of a castle destroyed, long ago, by God himself. In that time, the Knight Pontus was greatly saddened by his absence of heirs. ‘I must have a child, be it from the Devil or God!’ he declared, from the highest point of the highest tower of his castle. God heard nothing. But the devil was all ears. The Cunning One gave the knight his wish : nine months later, during a lunar eclipse, the Châtelaine brought into the world a little hairy creature. Barely out of the womb, the little devil jumped unto an enormous armoire and then found refuge under a sideboard. ‘ This is a sorry omen!’ announced the maid- servant before running off very scared.

At that time, there blew a great wind. The tempest came from the ocean. The forest was spared, but not the castle, which crumbled unto the inhabitants. A breath of the Apocalypse had brought down the ramparts leaving instead a magnificent beechtree, which looks down on Brocéliande to this day.


Source: Le Monde enchanté des arbres. France.

Phoenix

I’ve been waiting impatiently to hear about how the Phoenix landing went. It is now set for eight o’clock this evening. I cannot help but feel that it will bring us crucial information, will finally tell us that life can develop somewhere other than on our little planet, that it was not a total freak accident. Things did not get far because Mars is smaller than Earth and much further from the Sun.

If I were planning to visit Mars, the first thing I would worry about would be the lack of oxygen on the surface of the planet and how to remedy it. There is carbon dioxide in abundance, and some sunlight so that growing things is theoretically possible although, as thing now stand, the nights are incredibly cold (-80°C), even at the equator. The planetary high is listed at -5°C. Perhaps inside one of those craters, using mirrors, one might reach a reasonable temperature. And plan on covering things over for most of the 24-hour day. We now know there is silicium on the planet, glass would be one of the first industries. Yet growing things also needs nitrogen, soil nutrients, - in effect garbage – and abundant water above all. Not really impossible.

It will take six months for the first human travellers to reach Mars. That is a very long time. Perhaps they can install tanning facilities, to simulate sunlight. I would worry about keeping the air very clean on board. And personal hygiene. Who can go six months without new clothes. And another six months coming back, after the mission. That mission will demand great fortitude from a few people, mental strength not to be overwhelmed in conditions of being cut off from usual buoys of human sanity in the sequence of day and night and the experience of the outdoors through seasonal variations. Who can go that long knowing they will not be seeing anyone new, knowing that it is not even a remote possibility. Yes it will demand great fortitude. And it will also forge a new sensibility, watching the Sun and planet Earth through the window on a starry moment of rest. Mars has to be thought of as a possible home for us, as a place where a lone wolf of a human might eventually survive on his own for the entreprise to be viable. And romantic.

Mars Animations

These NASA ESA animations are great for the musical background.

http://spiegel.de/flash/0,5532,17965,00.html

Little Green Men!?

Cannes 2008

Alzheimer's

I'm happy to have found an article that finally explains in a clear way what Alzheimer's disease is about (in the New York Times Health section). It is basically aging in the brain, but need not impair everyone. Filaments within nerves get twisted, dead cells accumulate around these and in certain areas of the brain: it is a garbage disposal problem. Bottom line: the brain produces fewer neurotransmitters, those molecules between nerve cells that allow different parts of the brain to communicate with each other. Hence the symptoms: progressive memory loss, confusion, personality blanks.

The progression of the disease is predictable: the rapid variety has a genetic basis and declares itself before age 60. The slower form is linked with high blood pressure. Treatment is difficult, and made more complicated when interaction with other diseases - and their medication - is involved. Avoidance takes the form of clean living, anti-oxidants in the diet, and an active brain.

One aspect of the question is rarely discussed, and difficult to apprehend, and that is the lived experience of older people itself. I have noticed in myself that, as I age, I feel I have less time to loose and get impatient with social niceties. My entourage may feel I am becoming anti-social or resistant to change but, from this side of the event, the feeling is Been there!, Done that!, and Give me a break! I don't mind being talked about in stage whispers because that is part of social interaction for all age groups. But I feel there is a real lack of understanding about what is going on with me. For the first time in my life, there is no one around to reprimand me intelligently (or helpfully) except for other baby-boomers. The French call us pappy-boomers. We are a force to be reckoned with yet.

I do feel a need to pass on what I know: it seems totally wasteful to me that I should have spent half a lifetime learning calculus, or how to play Mozart on the piano with a proper German intonation and be taking that knowledge to the grave with me. I need air time; it is a sense of mission with me, like finding a mate was when I was eighteen. This is where the young misunderstand; it is not a need to control or meddle, I merely want to place my piece of the puzzle on the board.

The Times piece contained tantalizing bits of information on how memory works: the emotional context present when one first learned something is stored with it, and is an avenue to its retrieval ( which might explain why things learned more recently are sometimes forgotten quickly: Who cares?). Sensory input to the brain is localized on the outside areas, but memory storage will differ between individuals, with a brief passage to the frontal area which we call thinking or being aware. Is human memory like computer memory - an electrical pattern that is erasable - or indeed erased, when turned off. I would be curious to find out more on this. I have no doubt humanity will eventually manage the brain like we order sock drawers. I am saddened to think I won't be there to see it.

Free Zoo

Popfly Montreal

Going, Going...

Professional movie reviewers of the new German Film Postal - generally agreeing that it is of abysmal taste- 'The best we come hope for is to forget' and so forth, are perhaps lacking a crucial bit of information, indeed of general culture. The expression «going postal» actually means something. It is a reference to serial killing, as a result of the fact that postal workers (fired postal workers) have been known to go on murderous rampages at their ex-place of employment. This phenomenon is documented on Wikipedia. Why should this phenomenon be the case? Now there is a question worthy of being forgotten, and I am planning to.

Murderous rages are not new. The classical historian Suetonius informs us of the expulsion of Jews from Rome in the following terms: "since the Jews constantly made disturbances at the instigation of Chrestus, Claudius expelled them from Rome" a phrase understood to mean that the emergence of Christianity -at this point, 49A.D.- as a sect among the Jewish population of Rome led to a lot of noisy in-fighting. The whole lot were asked to leave. The Jewish religion had always been very progressive, and from ancient times non-Jewish followers were accepted so long as they followed Noah's laws prescribing: Idolatry, Murder, Theft, Sexual Promiscuity, Blasphemy, Cruelty to Animals (Do not eat flesh taken from an animal while it is still alive) and the requirement to have just Laws. But things got worse in Jerusalem where Rome wanted to impose it's own cult. The ensuing destruction of Jerusalem in 73 A.D. led to a siege that decimated 600 000 people, all of whom preferred death to surrender and the destruction of the Temple. Intolerance!

Ashkernazi (German) Jews make up some 80% of the current world Jewish population, but religious tolerance issues are at the fore yet in the Middle East. Maybe a little laughter at suicide bomber jokes isn't such a bad thing after all...