Thursday, December 07, 2006

Have a Stringy Christmas

What's new? Joe Polchinski's review 'All Strung Out?' of Peter Woit's and Lee Smolin's books over at CV (via Asymptotia). The choice of the title is quite ironic. I wonder if he knew this had almost been the title of Lee's book (without the question mark, I presume). The review is worth reading, whether you like or didn't like the books and/or authors.

Besides this new round in the discussion (I predict of order 200 comments over at CV), look what I found in my inbox: Stringy Christmas greetings from last December :-)

----- Original Message -----
From: "D****** M*******"
To: "KITP Lunch List"
Sent: Thursday, December 08, 2005 4:05 PM
Subject: [strings05] song lyrics

Here are the lyrics:


Song #2: The Maldacena, by Jeff Harvey (1998)

You start with the brane
and the brane is BPS.
Then you go near the brane
and the space is AdS.
Who knows what it means
I don't, I confess.
Ehhh! Maldacena!

Super Yang-Mills
with very large N.
Gravity on a sphere
flux without end.
Who says they're the same
holographic he contends.
Ehhh! Maldacena!

Black holes used to be
a great mystery.
Now we use D-brane
to compute D-entropy.
And when D-brane is hot
D-free energy.
Ehhh! Maldacena!

M-theory is finished
Juan has great repute.
The black hole we have mastered
QCD we can compute.
Too bad the glueball spectrum
is still in some dispute.
Ehhh! Maldacena!

This message is sent to you because you are subscribed to
the mailing list

----- End of Original Message -----


cvj said...

Hi Bee,

Do you know the circumstances surrounding that song's performance?

It involves about 400 theoretical physicists dancing in unison. Still a scary thought to this day. ;-)


Bee said...

Hi Clifford,

I read something about it! Were you there? Who came up with this crazy idea? And who sang best ;-) ? Best,


Plato said...

I think it has to do with this here

Your pretty artistic Bee. You should be able to come up with a new string tune?

Plato said...


A little history is always nice.

Something so abstract actually working within the system?

Strominger: Well, there are other ways that our confidence in string theory has been bolstered. One is the black hole story, in that Boltzmann's work in the 19th century, which showed that the theory of molecules could explain the laws of thermodynamics, was in itself indirect evidence for that theory of molecules, and played some role in the eventual acceptance of the theory. It was not a definitive role. The definitive discovery was when scientists could basically see the molecules. In the same sense, the black hole story was an unsolved problem from what seemed to be another branch of physics not directly associated with string theory. Now string theory has provided an explanation for that, and it is the only really robust explanation that has been provided. That is indirect evidence for string theory, or at least evidence that we're moving in the right direction.

Arun said...

Sorry if this is blather, but one needs to test one's understanding.

My understanding of the string black hole result is that the calculation was done in a particular limit where counting of modes and thus entropy calculation was actually possible.

Presumably, a blackhole from a supernova remnant, constituted mostly of standard model matter, corresponds to a rather different sector of string theory.

1. there had better be a mode-for-mode match between the blackhole string theory and the string theory that describes baryons and our universe.

2. there had better be no physical process that can transform one to the other (or else the string theory estimate is a lower bound on the entropy).

Unless one shows these two things, it is not clear to me that we've gotten much further along.

Plato said...
This comment has been removed by a blog administrator.
Plato said...


That was the problem we had to solve. In order to count microstates, you need a microscopic theory. Boltzmann had one–the theory of molecules. We needed a microscopic theory for black holes that had to have three characteristics: One, it had to include quantum mechanics. Two, it obviously had to include gravity, because black holes are the quintessential gravitational objects. And three, it had to be a theory in which we would be able to do the hard computations of strong interactions. I say strong interactions because the forces inside a black hole are large, and whenever you have a system in which forces are large it becomes hard to do a calculation.

What is black hole entropy?

When it was discovered that black holes can decay by quantum processes, it was also discovered that black holes seem to have the thermodynamic properties of temperature and entropy. The temperature of the black hole is inversely proportional to its mass, so the black hole gets hotter and hotter as it decays.