Saturday, September 08, 2007

Readings, 8 September 2007



Today's edition deals with physics and mathematics.

The text following each item is quoted material, except for editorial comments, which are in color.


Stringscape
In its near 40-year history, string theory has gone from a theory of hadrons to a theory of everything to, possibly, a theory of nothing. Indeed, modern string theory is not even a theory of strings but one of higher-dimensional objects called branes. Matthew Chalmers attempts to disentangle the immense theoretical framework that is string theory, and reveals a world of mind-bending ideas, tangible successes and daunting challenges – most of which, perhaps surprisingly, are rooted in experimental data.

Quite a substantial article. You might prefer to read it in the PDF form. You are probably aware – because it has been splashed all over the popular media – that many physicists and philosophers of science are skeptical of string theory. They have many good points to make. But string theorists have good points of their own to make, and this article makes a lot of them. And even prominent critics of string theory, such as Sheldon Glashow and Gerard 't Hooft, are quoted acknowledging some of these points.

Are Planetary Systems Filled to Capacity?
Computer simulations suggest that the answer may be yes. But observations of extrasolar systems will provide the ultimate test.

This is a more interesting topic than it might at first seem. For one thing, there have long been questions about the stability of many-body systems such as the solar system – especially since we now understand more about the fact and implications of "chaotic" behavior. But also the fact we can now observe distant extrasolar planetary systems opens the possibility of comparing theory to reality. One consequence of the ideas described here is that planets in a "habitable zone" around their star may not be all that unlikely.

Higher Games
It's been 10 years since IBM's Deep Blue beat Garry Kasparov in chess. A prominent philosopher asks what the match meant.

Some philosophers, who understood neither chess nor computers all that well, used to predict that a computer could never beat the best human players. Daniel Dennett was not one such philosopher.

Chasing down zeros at math camp
In sessions at the American Institute of Math, geniuses munch food and crunch numbers, contemplating labyrinthine ideas.

Although this article disses modern mathematics in the customary way of those who equate math with the ability to balance a checkbook, it does manage to convey some flavor of what the American Institute of Mathematics is about.

Math Plus Cryptography Equals Drama And Conflict
Cryptography is just about as old as written communication itself, and mathematics has long supplied methods for the cryptographic toolbox.

Starting in the 1970s, increasingly sophisticated mathematics began to make inroads into cryptography, changing the nature of the field and bringing new perspectives on what it means to keep communications secure.

Neal Koblitz has written textbooks with titles like p-adic Numbers, p-adic Analysis, and Zeta-Functions. Nevertheless, his article The Uneasy Relationship Between Mathematics and Cryptography, described in the above press release, is accessible and discusses a practical side of very abstract mathematics.

Toiling in the Fields of Physics
The huge warehouse seems out of place in the French countryside, surrounded by pastures and cornfields. And if the farmers who work those fields were to take a look inside the structure, they might be forgiven if they thought space aliens had dropped a flying-saucer factory in their midst. Sticking up from the warehouse floor are massive disks of metal, lined up in a row and rising more than four stories into the air.

These are pieces of the Compact Muon Solenoid, one of the four major detectors being built for the world's most powerful particle collider.

For the next year or two there will be tons of articles appearing on the Large Hadron Collider. Get used to it.

Putting electronics in a spin
When engineers flick the switch to turn on the world's fastest supercomputer later this year it will be capable of chewing its way through 1,000 trillion calculations every second.

About the technology of spintronics, which is already affecting consumer electronics, and may eventually make quantum computing possible.

The Gedanken Experimenter
In putting teleportation, entanglement and other quantum oddities to the test, physicist Anton Zeilinger hopes to find out just how unreal quantum reality can get.

Zeilinger works in the fields of quantum information (pertinent to quantum computers) and the question of "quantum reality".

What Visions in the Dark of Light
Lene Vestergaard Hau made headlines by slowing light to below highway speed. Now the ringmaster of light can stop it, extinguish it and revive it—and thereby give quantum information a new look.

Hau's field is quantum optics, another area of possible relevance to quantum computing.

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