Quantum Bayesian Networks

January 1, 2012

My Prediction for 2012: Quantum Computerists Will Occupy String Theory Bastions Like Princeton’s IAS

Filed under: Uncategorized — rrtucci @ 4:13 am

Quantum Computer Programmers Too

“String theorists don’t make predictions, they make excuses” -Feynman (1918-1988)

In America during the 1960’s, the hippies and draft dodgers rose up against the powers that be. At present, a similar phenomenon is sweeping through many Islamic countries (the so-called Arab Spring), and America (the Occupy Wall Street protest movement). It seems that every 50 years or so, the young rise up against the ruling class elites and abusers of power.

I predict that in 2012, a new protest movement will bubble up from that boiling cauldron of unrest that is Academia, and start a new String Theory revolution.

I, Nostradamucci, see the future clearly. The end times. A world in turmoil. Four horsemen. QC barbarians at the String Theory ramparts. En masse occupation of IAS by quantum computerists. Mass defections from the String Theory ranks to the QC ranks. A Great Cheapening of the once venerable String Theory brand. The QC Winter. The end of innocence.

There have been some recent, very foreboding developments at the crossroads between high energy physics and quantum computing, that give my prediction an air of inevitability. Here are some of those ominous signs:

  • In a previous blog post of mine,

    Set a Thief to Catch a Thief

    I gave a brief historical review of the idea of simulating quantum mechanical systems using a QC.

    There is a steadily increasing logjam of quantum mechanical theories (examples can be found in the fields of quantum gravity in general, String Theory in particular, relativistic quantum field theory, condensed matter physics, etc. ) that resist analysis in their strong and intermediate coupling regimes, regimes where an expansion in powers of the coupling constant fails to converge. So far nobody knows how to milk such theories very well.

    Perhaps if we could simulate such theories on some kind of computer, we could compare their predictions with laboratory measurements. We might then be able to discard or modify or refine those theories. We might also be able to simplify such theories to their sweet spot, the spot where they are simple enough that we can figure out how to solve them analytically, yet complicated enough that they still make useful predictions which agree reasonably well with the laboratory data.

    A QC would be the ideal device for simulating such currently intractable quantum theories. Feynman himself was the first to point out that using a QC instead of a classical computer to simulate a quantum system allows one to perform such simulations faster by a factor exp(n), where n is the number of bits in the input data. Also, no need for iffy Wick-y rotations. And QCs can simulate both the strong and weak coupling regimes of a theory with the same software code and with the greatest of ease.

  • Recently, some researchers have proposed in the following paper, a method similar to the methods discussed in the above Thieves post, but this time for using a QC to simulate the phi^4 relativistic quantum field theory in 3+1 dimensions. They have worked out some of the nitty-gritty details of Feynman’s original dream:

    Quantum Computation of Scattering in Scalar Quantum Field Theories
    Stephen P. Jordan, Keith S. M. Lee, John Preskill

    Papers that give methods for doing QC simulations of quantum field theories that also include fermions and gauge fields, are no doubt being written as we speak. Much work remains to be done in this area. All the details of how one would simulate a String Theory on a QC remain undiscovered yet. Maybe you will be the one who finds them.

  • Lattice Gauge Theories were invented circa 1974 by Ken Wilson and others. It has taken scientists many decades of grueling work, using Monte Carlo techniques on classical supercomputers, to simulate lattice QCD (Quantum Chromodynamics), and to derive the mass spectra predicted by it. Imagine if QCs could do all that work in seconds.

    On classical computers, to reduce the computational-resource requirements to a non-prohibitive size, one is often forced to butcher the fermionic degrees of freedom of the lattice gauge theory by using ugly, poorly understood approximations. This would not be necessary if the simulations were done on a QC.

    QCs can do Monte Carlo much faster than classical computers, a fact which I’ve explained in many previous posts in this blog, and which I exploit in my own QC Gibbs sampling software called Quibbs.

  • Recently there have been some paltry attempts to use disgustingly classical supercomputers to try to squeeze out some straight answers from String Theory. Quantum computers could do such analyses much more quickly, accurately and painlessly.

  • Machiavelli speaks: Ascolta, mio principe (Listen, my Prince): String theory is a hard subject to sell to the general public. No verified quantitative predictions so far. No practical applications. But if string theorists start selling themselves by saying that we are helping to develop quantum computers at the same time that we explore our theory, they might get some new buyers. Even the military and DARPA, which don’t normally fund string theorists, might bite.

  • An anonymous quantum computerists, probably an ex-physicist working in Wall Street, recently sent me the following wordy, demented manifesto for a protest movement that he is trying to start:

    We are the 99% who are not String Theorists. Let’s now define the set of people who are not String Theorists as being Quantum Computerists, just like Lilliput had its Big Enders and Small Enders. We Quantum Computerists believe that String Theorists who work at primo places like Princeton’s IAS (the Institute for Advanced Study, where Ed Witten works, where Einstein and Godel once worked, a place rated by Sidney Coleman as the most boring town he has ever lived in) control too much of the wealth (in funding booty, post doc slaves and public imagination) of physics. And so far String Theorists have squandered that wealth and patrimony.

    Let’s face it, investments in String Theory were a huge gamble from the very beginning—I mean, even at its christening, Feynman didn’t give his blessing to John Schwarz’s baby, but Feynman certainly did give his blessing to his own baby, quantum computing.

    String Theorists have failed miserably to balance their books (no good quantitative agreement between the two sides of the ledger, theory and experiment). But they are not being held accountable for their poor book-keeping practices. They continue to be bailed out by the government because their business is considered too big to fail, according to Peter Woit.

    Even after the Great Recession caused by multiverse ideas, most String Theorists still deny that they ever did anything wrong. They continue to do business as usual, steadfast in their Enron-esque opinion that they are the smartest people in the room, and, therefore, they can do no wrong. Well, I’ve got news for them, some quantum computerists (most notably the complexity theorists) think they are even smarter. (note from rrtucci: Leave me out of it. I belong to the 99% of the 99% who are as blissfully dumb as Ed Witten’s hamster.)

    We quantum computerists are not against laissez faire capitalism. That would be like being against truth, justice and the American way. So we are not against String Theory per se either, or against any other lesser theories of quantum gravity. What we deplore is that the gains made by String Theorists in the past few decades are not trickling down to us.

    Let’s face it. String Theory is as transparent as a Credit Default Swap. Perhaps quantum computerists can make String Theory more transparent by simulating various facets of it on a quantum computer?



  1. There’s no doubt QC will do wonders once Feynman’s vision comes into fruition. But I think there’s more to it than that. On route to getting a gate programmable quantum computer we learn a great deal about the nature of decoherence and entanglement. There is a reason that a simple quantum optic experiment performed at the university of Toronto has been voted top physics breakthrough of 2011. The old dogma of “shut up and calculate” that the Copenhagen interpretation reinforced is slowly eroding. I find this very exciting – theoretical physics is going to become more fun again.

    Comment by Henning Dekant — January 3, 2012 @ 4:56 am

  2. I have no doubt every physicist loved physics and discovery as a child. They reflect on that past innocence when they are lecturing at high schools or talking to the general public. What they won’t say is that time of innocence is the past. It is replaced with meaningless publications, scavenging for the little grant money they can find while telling their post docs to be quite concerning innocent questions that might damage their chances of getting promoted. Einstein was great because he did his best work when he was innocent and he maintained that innocence as a PH.D. It was that innocence and freedom to ask the right questions that got him banished from physics, yet celebrated as an old classical thinker. The revolution science seeks will not come from crack pots or established drones. It will come from where it always has, those who continue to love physics as a child.

    Comment by Jamahl Peavey — February 28, 2012 @ 2:06 pm

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