Let me Count the Ways

A slightly famous mathematician once said to me: “I think Hawking is the most overrated physicist.” This took me aback, and I spent quite a while explaining to him that Hawking had important results in addition to his appearances on Star Trek and The Simpsons.

Most important was his discovery of black hole radiance, and the revolution in black hole statistical mechanics it energized, which in turn is the most important result of quantum gravity. I suppose it would be more precise to say that black hole radiance and black hole thermodynamics is the nearest thing to a result in quantum gravity, since there are no experimentally confirmed predictions in quantum gravity.

Nonetheless, all roads in quantum gravity appear to lead to black hole thermodynamics, and it would be hard to find a yet unobserved phenomenon in which physicists believe more firmly. Steven Carlip gives an overview of those many paths leading there in his new paper Black Hole Thermodynamics and Statistical Mechanics (arXiv:0807.4520). Among them, classical thermodynamic arguments, semi-classical quantum field theoretic arguments, statistical mechanical arguments based on string theory, Maldacena’s ADS/CFT, loop quantum gravity calculations, Sakharov’s induced gravity, entanglement entropy, and derivations from causal sets.

What accounts for this universality of result from seeming very different approaches? That’s the question that interests Carlip, but he doesn’t have a definitive answer. He does have what he thinks is a tantalizing clue, but you will need to read the paper to get that.

Comments

Post a Comment

Popular posts from this blog

Anti-Libertarian: re-post

The most pointed critique of social security and liberalism in general is the libertarian critique. The problem with libertarians, for a liberal, is that we have too much in common. We both believe in individual rights, tolerance of individual differences, and dislike government prescription of religion. The basic difference, it seems to me, is the different answers we give to Cain's (with thanks to the Captain - my original version had the corpse asking the question!) famous question: "Am I my brother's keeper?" That's not really my basic bitch against the libertarians though. My real complaint is the same as my complaint against most religion - its premise is a fraud. For those who can't stand to wait for the punchline, I believe that trying to implement libertarian principles leads to tyranny or social disintegration. Demonstrating that takes some historical (and pre-historical) context. For all but the last 15,000 or so of the 100,000 years the human spec
Read more

Uneasy Lies The Head

Uneasy lies the head that wears a crown ........... Shakespeare Henry IV, Part II. So it is with us and our slightly distant primate cousins , so it seems. A 9-year study of wild baboons in Kenya by Princeton University and the Institute of Primate Research may turn conventional assumptions of alphas males upside down. The study found that alpha males have high testosterone levels, which allows them to dominate other baboons, get access to more food, and attract better mates. This is expected. Surprisingly, though, the alpha males also have high levels of stress hormone glucocorticoid, which scientists measured from their feces samples. In fact, the stress of alpha baboons was on par with low-ranking baboons. The convention wisdom is that access to food and females provides life security and thus less stress for dominant males. Conversely, weak males who are constantly threatened by starvation and physical violence from stronger males are thought to be more stressed. The st
Read more

We Call it Soccer

The US played its best, and maybe only good game of World Cup, but lost thanks to brilliant goalkeeping by the Swedish keeper and the bizarre method soccer uses to settle ties when three US stars could not put the ball on frame from the 12 yard spot.  At the end it came down to a blocked shot that spun in by maybe a couple of centimeters. Well, that's football - too much like life.   Which brings me to a modest proposal.  Replace the thirty minute overtimes with as many 7-player 15 minute periods as needed to settle it.  Scoring should be much easier with fewer players.
Read more