Honoring Asher Peres: Reflections on "The Cat Who Walks by Himself

[marcus]

thanks to Robphy for corrections:

Asher Peres would have been 71 years old this year, and last year a special issue of Foundations of Physics was published honoring him on his 70th birthday with articles written by his friends. He wrote a biographical memoir for it called

"I am the Cat Who Walks by Himself"
http://www.arxiv.org/abs/physics/0404085

It tells the adventures of a boy in France and Israel in the forties and fifties who survived those adventures to become a worldclass quantum theorist.
And Daniel Terno is apparently a protege of Peres who has written many papers with Peres about the foundations of quantum theory AND how that spills over into QUANTUM COMPUTING (getting more and more interesting)

And now Daniel Terno has taken up with the Quantum Gravitist postdoc Etera Livine who also impresses me as the sort of cat who walks by himself and who put an amusing quote from the Babylonian Talmud at the beginning of his 2003 Lyon University PhD thesis.

so we are in the presence of unpredictable people who occasionally have ideas or do other interesting things.

And Daniel Terno and Etera Livine, both being at Perimeter in Waterloo, have started writing about LQG and black holes and qubits and entropy and area and horizons and quantum computing.

It would be entertaining if some of what they say would turn out to be not merely cockeyed wacky peculiar but also right. It certainly is peculiar, or seems so to me. If there is even a grain of truth it would be a lot of fun.
I don't understand it, or I'd try to explain. Maybe someone else can.

QUANTUM BLACK HOLES: ENTROPY AND ENTANGLEMENT ON THE HORIZON
http://arxiv.org/gr-qc/0508085

I put some more detail in the QG reference links thread

https://www.physicsforums.com/showthread.php?p=720728#post720728

They have another paper in the works called
"Reconstructing Quantum Geometry from Quantum Information: Entanglement as a Measure of Distance"

the cat who walks by himself is a reference to a Just-So story by Rudyard Kipling http://www.boop.org/jan/justso/cat.htm

 

[robphy]

http://www.technion.ac.il/~peres/
http://quantum.fis.ucm.es/article.pl?sid=05/01/04/1434238&mode=thread
"Quantum information science lost one of its founding fathers. Asher Peres died on Sunday, January 1, 2005. He was 70 years old."

 

[marcus]

Thanks Robphy.
While I'm at it, here's Livine's thesis, for the sake of its two choice epigraphs
http://www.arxiv.org/abs/gr-qc/0309028

Douter de tout ou tout croire, ce sont deux solutions également commodes, qui l’une et l’autre nous dispensent de réfléchir.

Poincaré, la Science et l’Hypothèse



Quiconque s’est jamais avisé de spéculer sur ces 4 questions :

– Qu’y a-t-il au-dessus ?
– Qu’y a-t-il en-dessous ?
– Qu’y avait-il avant le monde ?
– Qu’y aura-t-il après ?

Il aurait mieux valu pour lui qu’il ne fut jamais né.

Talmud de Babylone

It is droll for a Quantum Gravitist to be warning against asking these questions because these are exactly the questions confronting one who delves into the fundamental nature of space and time. The epigraph appears both ironical and rueful.

Here is a photo of Etera Livine. He is the happy guy with the straight teeth:
http://math.ucr.edu/home/baez/marseille/livine.jpg

 

[marcus]

The link that Robphy gave
http://www.technion.ac.il/~peres/
is a very nice link about Asher Peres, and it has a photo of Dani Terno with two other of Peres graduate students.

Terno got his PhD in 2003 (same year as Etera Livine, so they are about the same generation)

Daniel is the one in the leather motorcycle jacket and the little patch of beard on his chin

this kind of collaboration, like between Terno and Livine, could be an interesting kind of collaboration----between LQG on the one hand and the methods and outlook from the field Peres helped create:
quantum information/quantum computing/teleportation/entanglement/encryption/quantum foundations.

I can't describe Peres field firsthand, so I will just say "quantum information" study.

so it is to combine Loop Quantum Gravity, and its picture of black hole, with "quantum information science" methods.

Maybe someone wants to say this more cogently?

Anyway, let's look some more at the Livine/Terno paper that just came out.

 

[marcus]

I gave a link to this in the original post of this thread

http://arxiv.org/abs/gr-qc/0508085
Quantum Black Holes: Entropy and Entanglement on the Horizon
Etera R. Livine, Daniel R. Terno
25 pages, 4 figures

"We are interested in black holes in Loop Quantum Gravity (LQG). We study the simple model of static black holes: the horizon is made of a given number of identical elementary surfaces and these small surfaces all behaves as a spin-s system accordingly to LQG. The chosen spin-s defines the area unit or area resolution, which the observer uses to probe the space(time) geometry. For s=1/2, we are actually dealing with the qubit model, where the horizon is made of a certain number of qubits. In this context, we compute the black hole entropy and show that the factor in front of the logarithmic correction to the entropy formula is independent of the unit s. We also compute the entanglement between parts of the horizon. We show that these correlations between parts of the horizon are directly responsible for the asymptotic logarithmic corrections. This leads us to speculate on a relation between the evaporation process and the entanglement between a pair of qubits and the rest of the horizon. Finally, we introduce a concept of renormalisation of areas in LQG"

 

[marcus]

TWO EQUALLY CONVENIENT SOLUTIONS ARE TO BE COMPLETELY CREDULOUS OR COMPLETELY SKEPTICAL BECAUSE EITHER WAY YOU DONT HAVE TO THINK.

Douter de tout ou tout croire, ce sont deux solutions également commodes, qui l’une et l’autre nous dispensent de réfléchir.

Poincaré, la Science et l’Hypothèse

IT IS NOT ADVISABLE FOR ANYBODY TO ASK THESE FOUR QUESTIONS

WHAT IS ABOVE?
WHAT IS BELOW?
WHAT CAME BEFORE THE WORLD?
WHAT COMES AFTER?

SOMEONE ASKS SUCH QUESTIONS, BETTER FOR HIM THAT HE WAS NEVER BORN.


Quiconque s’est jamais avisé de spéculer sur ces 4 questions :

– Qu’y a-t-il au-dessus ?
– Qu’y a-t-il en-dessous ?
– Qu’y avait-il avant le monde ?
– Qu’y aura-t-il après ?

Il aurait mieux valu pour lui qu’il ne fut jamais né.

Talmud de Babylone

I'm translating the epigraphs (titlepage quotes, header quotes) that Livine used in his thesis, in case of readers being French-less.

Again, here is a photo of Livine.
http://math.ucr.edu/home/baez/marseille/livine.jpg