My Nobel Nomination

As Frank got his well deserved and long awaited Nobel this year I can announce my second group in my nomination list. Well, Nobel committee do not send me nomination forms but I can use the freedom of blogs. I would suggest; Edward Lorenz and Benoit Mandelbrot.

Their contribution to physics is well above the Nobel standards. They opened up a totally new field which evolved into one of the major branches in physics. With the insights of chaos and fractal geometry we understood a great deal in everyday physics and beyond. Since their work is incredibly original, firm in mathematical background, tested experimentally in thousands of intrinsically different situations and the influence on physics is immense; I can not understand why they haven't got it yet. As they are both over 80, I would suggest 2005 to be their year. I hope somebody reading this has a nomination form.

Please feel free to send your Nobel suggestions as comments.

Coleman Fest: Day 2

Lubos, Peter and David very well summarized the second day so I don't need to spend your and my time. Instead I want to focus on another question, Gross briefly and Witten extensively talked about. Can we make spacetime emergent?

I think the question needs better definition. What they are giving as examples right now is indeed extremely interesting. Two theories living in two different spacetime dimensions can be "dual". This means that every calculation done in one way, can be done in the other and give the same result. I personally would not call these dual theories as emergent. Material continuum is an emergent realization of atoms. So if you want to make a theory with emergent spacetime I would think that dimensions are build from discrete geometries or some other totally different mathematical structure which effectively geometric at large "distances", whatever it means in this case. My humble intuition for the current situation is that it is a manifestation of the gauge redundancy in our theories. They can be reduced (somehow) not only by changing the field degrees of freedom but a combination of spacetime and gauge degrees, since the former is also dynamical in the gravitational theories. But you may need to introduce new redundancies in the second theory. Zee speculates in the last chapter of his marvelous book that our gauge language may not be the best one to represent nature since it includes unavoidable redundancies. Most probably dual theories will have the same or trivially related representations in the ultimate language when we find it.

I don't want to alert anybody out there unnecessarily. I should say that everything Gross and Witten said is accurate for our current understanding, but the word emergent might be confusing since it is used in many different contexts these days. And there is no sign of inaccuracy of the gauge language; it is just hard to play with for the human mind despite its all elegancy.

I also had an opportunity to eat the lunch with David Gross, Frank Wilczek, Stephen Wolfram (Mr. Mathematica), Leonard Parker (who wrote the apparently useful but ridiculously expensive Mathematica package MathTensor) and Jack Ng (who wrote interesting papers on unimodular gravity which I am currently interested in). Wolfram was trying to convince Gross and Wilczek for the enumerability of the physical laws. (Well, they were not amused.) He would like to give brute force search. I am quite skeptical that we can recognize even if we hit the right one. Wolfram is unquestionably a smart guy. I can't say that I buy his cellular automaton ideas but community might be too harsh on him. We always need someone outside the crowd. He also announced us the latest upcoming service from the Wolfram companies but probably I should not say it hear. One teaser: it is about cell phones!


Lively debate (clockwise): Ng, Parker, Gross, Wilczek, Wolfram, Cabi

It was sad to hear that Coleman does not feel well. Shame on me that I have not read his book yet. This week should be the time.

Coleman Fest: Day 1

Today I've seen the Mount Olympus and came back to my humble room. Harvard organized a conference in honor of great mentor Sidney Coleman. I have never seen a greater concentration of physics talent. First day's speakers were David Gross, Frank Wilczek, Paul Steinhardt, Murray Gell-Mann and Sheldon Glashow!

Gross (who made me so flattered by calling me "grandson") gave the recent talk on "The Future of Physics". It is blogged elsewhere and you can watch it yourself here or here. Even though most approachable and promising question seems to be the dark energy, I am also deeply interested in the possibility of emergent spacetime. I am told by Gross that IIB matrix models in string theory gives four spacetime dimensions without any preliminary reference to space. Even if string theory will not survive eventually, these dual theories will certainly have great theoretical and philosophical implications in the future. There is also Wilczek's question of training artificial intelligence physicists, but this is whole another blog. (Related: Take a look at New Scientist's list of puzzling phenomena.)

Secondly Wilczek gave an illuminating talk on the past of QCD which was very similar to his Nobel lecture. Next, it was interesting to listen Steinhardt on cyclic universes. This was my first exposure to the idea beyond some press releases. This is much better grounded than I initially thought, but still confused why the asymptotic behavior of the scalar field potential is almost zero. This seems to me a crucial step to be explained.

Gell-Mann and Glashow gave entertaining anecdotes. Gell-Mann had a remarkable critic of the current institutes that they do not promote collaboration between post-docs and graduate students enough. Gell-Mann and Glashow had a wonderful partnership in this way. Glashow's story of a Russian meeting was very funny but unfortunately I can not reproduce it here.

Tomorrow's speakers will be Erick Weinberg, Steven Weinberg, Gerard 't Hooft and Edward Witten. This time I'll be in Mount Olympus with my camera.

A final comment: Can Harvard make videos of Sidney's QFT lectures available online? They are only in the Harvard library for overnight loan. Sharing is not a Harvardish policy but I am still hopeful from the Jefferson Lab gang ;)

Rapid Physics History Test

As I was sitting on my desk, thinking on the near future of physics I found myself writing keywords for the decades future and past. Though it is incredibly incomplete and one (high energy) sided I put it here untouched for your thought provocation. I did not mean to give the discovery dates but the areas which were most lively and exciting those days. Take it as physicist psychology test where you should give the first thing you remember in physics for the decade. Feel free to attack and put your own versions. By the way, what is your guess for 2030's?

1890's Electron
1900's Special Relativity
1910's General Relativity
1920's Quantum Mechanics
1930's Relativistic Quantum Mechanics
1940's Nuclear Physics
1950's QED
1960's Electroweak Theory
1970's QCD
1980's Electroweak Experiments
1990's Neutrino Physics
2000's Cosmology
2010's LHC
2020's Gravitational Waves
2030's ???

I found a much more professional timeline here by APS.

Universe accelerated beyond the horizon

As I was trying to keep myself busy with modifications of general relativity, I came across to the new paper of the famous cosmologist Kolb and colleagues. They claim that inflation today is created by the primordial fluctuations stretched beyond the horizon. Approach is extremely conservative and the final diagram is very impressive. My first intuition about the super-Hubble modes is that they are just flat ground states here inside the horizon, but this is not enough to drive acceleration it has to dilute much slower than matter. The statistical reason for that is not crystal clear to me, but may be I shouldn’t feel bad because it even puzzled Sean Carroll. He thinks that nothing beyond the horizon can influence us.

For the records, I should say that I did not like the proposed solution. We always thought that solution of the acceleration of the universe puzzle will also solve two other great mysteries. Namely; why we do not see a cosmological constant in the Einstein-Hilbert action although the known symmetry principles allow it, and why the QFT vacuum condensates (ground state) do not gravitate; or why they cancel out. If the acceleration is due to super-Hubble fluctuations, I think we will be in a worse trouble. At least they are offering observable differences from a pure cosmological constant and nature will say the last word.

Physics of computer games and PhysX

I miss the good old days when I had time for playing computer games for long hours. I remember that time when I first saw a book on game physics. I had never thought of them as a physics problem. It seems that the market in this area have grown since then. Now I see that the problem can be very interesting. Find an algorithm for classical mechanics so that you can allow low precision in position and momentum but still the long term behavior 'looks' reasonable and the complexity is optimized. What is the best compression (or in physics language: coarse-graining) algorithm for (classical) physical reality? There might be something deep lying there, but I assume people are just using the enormous power of today's computers. Do you remember playing less than 1MB games for days on a 286? Programming must be much more fun and challenge at that era.

That was the software part. On the hardware side, specialized processors for celestial mechanics simulations are not new for physicists. Now there is a commercial physics processor available for game physics calculations: PhysX. Do you think that a physics processor will be a standard component of computers like math and graphics chips? I believe it is an essential component for computers that interact with its physical environment. Any way, this chip is a nice event for the year of physics.

Gravity from symmetry breaking

Ingo Kirsch, a post-doc from Harvard, submitted an interesting paper on arXiv today. Goal is to get gravitational structure from almost nothing and symmetry breaking. He shows that a spacetime just made out of a manifold and a symmetry breaking Higgs field under certain potentials can give rise to a Riemann structure. In other words connection and the metric can be Goldstone modes of the theory. This work is a follow up and generalization of ghost condensation idea from the same (Arkani-Hamed) group.
I could not follow all the group theoretic ideas in the paper. I need more patience and to go back to the study desk for basics. However it reminds me the earlier work of Wilczek, where he gets the metric field out of symmetry breaking of a gauge structure and a preferred volume.

Something for everybody

Yesterday Wilczek gave a wonderful public talk on the triumphs and prospects of our deepest understandings of nature. I am amazed that he can always maintain a level such that it is educative for the layman as well as motivating for the scientists. So probably it is a better idea to keep it short and watch the great mind.

Bosons from Fermions or Fermions from Bosons!?!

I want to take your attention to a recent proceeding paper by the grandmaster Anthony Zee. I didn't have a chance for an in-depth look but it is certainly thought provoking at the first sight.

He is challenging the idea of thinking fermions as more fundamental than bosons since you can make bosons as bound states of fermions but not vice versa. He is reminding us a very old result that "eigenstates of a charged boson in the presence of a magnetic monopole have half-integral angular momentum". So why can't the fermions be bound states of monopoles and bosons? He wildly continues other speculations. Have fun!

Axiomatic

I had a silent week. Besides working on my research and finally reading the last chapters of Zee's masterpiece, I read the sci-fi book Axiomatic by Greg Egan. He is a physicist, a gifted writer and dreamer. I first met him with Permutation City last year. Dust hypothesis proposed there is still a brain-twister for me. To make a long story short, the idea is; what if there is no connection between different spacetime points with different field configurations. They all exist separately and our universe is just one of its organizations. Like a big bunch of letters actually contain all the novels on earth simultaneously.

Axiomatic is a collection of short stories. Each one of them is a snapshot of quite an original universe. Make your brain a delightful favor and read this book. Mr. Egan is certainly making his way to the top of my list of greatest sci-fi writers of all times.