The big news today is the announcement of the nominees for the 2014 Fundamental Physics Prize: (1) Michael Green and John Schwarz, for pioneering contributions to string theory, (2) Joseph Polchinski, for discovering the central role of D-branes in string theory, and (3) Andrew Strominger and Cumrun Vafa, for discovering (using D-branes) the microscopic origin of black hole entropy in string theory. As in past years, all the nominees are marvelously deserving. The winner of the $3 million prize will be announced in San Francisco on December 12; the others will receive the $300,000 Physics Frontiers Prize.
I wrote about my admiration for Joe Polchinski when he was nominated last year, and I have also greatly admired the work of Strominger and Vafa for many years. But the story of Green and Schwarz is especially compelling. String theory, which was originally proposed as a theory of the strong interaction, had been an active research area from 1968 through the early 70s. But when asymptotic freedom was discovered in 1973, and quantum chromodynamics became clearly established as the right theory of the strong interaction, interest in string theory collapsed. Even the 1974 proposal by Scherk and Schwarz that string theory is really a compelling candidate for a quantum theory of gravity failed to generate much excitement.
A faithful few continued to develop string theory through the late 70s and early 80’s, particularly Green and Schwarz, who began collaborating in 1979. Together they clarified the different variants of the theory, which they named Types I, IIA, and IIB, and which were later recognized as different solutions to a single underlying theory (sometimes called M-theory). In retrospect, Green and Schwarz were making remarkable progress, but were still largely ignored.
In 1983, Luis Alvarez-Gaume and Edward Witten analyzed the gravitational anomalies that afflict higher dimensional “chiral” theories (in which left-handed and right-handed particles behave differently), and discovered a beautiful cancellation of these anomalies in the Type IIB string theory. But anomalies, which render a theory inconsistent, seemed to be a nail in the coffin of Type I theory, at that time the best hope for uniting gravitation with the other fundamental (gauge) interactions.
Then, working together at the Aspen Center for Physics during the summer of 1984, Green and Schwarz discovered an even more miraculous cancellation of anomalies in Type I string theory, which worked for only one possible gauge group: SO(32). (Within days they and others found that anomalies cancel for E8 X E8 as well, which provided the impetus for the invention of the heterotic string theory.) The anomaly cancellation drove a surge of enthusiasm for string theory as a unified theory of fundamental physics. The transformation of string theory from a backwater to the hottest topic in physics occurred virtually overnight. It was an exciting time.
When John turned 60 in 2001, I contributed a poem to a book assembled in his honor, hoping to capture in the poem the transformation that Green and Schwarz fomented (and also to express irritation about the widespread misspelling of “Schwarz”). I have appended the poem below, along with the photo of myself I included at the time to express my appreciation for strings.
I’ll be delighted if Polchinski, or Strominger and Vafa win the prize — they deserve it. But it will be especially satisfying if Green and Schwarz win. They started it all, and refused to give up.
To John Schwarz
Thirty years ago or more
John saw what physics had in store.
He had a vision of a string
And focused on that one big thing.
But then in nineteen-seven-three
Most physicists had to agree
That hadrons blasted to debris
Were well described by QCD.
The string, it seemed, by then was dead.
But John said: “It’s space-time instead!
The string can be revived again.
Give masses twenty powers of ten!”
Then Dr. Green and Dr. Black,
Writing papers by the stack,
Made One, Two-A, and Two-B glisten.
Why is it none of us would listen?
We said, “Who cares if super tricks
Bring D to ten from twenty-six?
Your theory must have fatal flaws.
Anomalies will doom your cause.”
If you weren’t there you couldn’t know
The impact of that mightly blow:
“The Green-Schwarz theory could be true —
It works for S-O-thirty-two!”
Then strings of course became the rage
And young folks of a certain age
Could not resist their siren call:
One theory that explains it all.
Because he never would give in,
Pursued his dream with discipline,
John Schwarz has been a hero to me.
So please, don’t spell it with a “t”!
I put your prediction on https://preddict.com We’ll see if it comes true 🙂
Dear John and others (including readers),
This is not a comment about the prize or the predictions. It concerns a certain point which I wanted to raise sometime. Might as well do it right now.
When people talk about things like quantum gravity or string theory, I am reminded of some *other* things that some *other* people worry about, e.g., the in-principle “ex post facto” nature of all these theories.
But that is not the only thing that crosses my mind, even if it is the most important consideration to me, of course. There also is something else that one invariably ends up wondering about: What does a new (claimed) advance here imply for the (classical) electromagnetic gravity theory? And, it also is to this question that I never find any answer.
If someone does have a theory for the *quantum* nature of gravity, shouldn’t it be possible for him to state something, in terms understandable to an engineer, about what his theorization translates to, for an *electromagnetic* nature of gravity (or the gravitational nature of electromagnetism)? Here, EM is to be taken in the classical sense (I mean as the good old Maxwellian EM).
It is of course understood that such a would be a wrong theory because the EM phenomena are not Maxwellian in nature; they are quantum mechanical. No point in engaging in drum-beating about the obvious. The point is not that.
The point is: can’t we have at least one quantum gravity/string theorist who cares to explain to “the layman” i.e. engineer what his own theory looks like in the classical limit (for the quantum part of his theory)? And, more: What the other competing theories look like, and what the distinctive or advantageous features of his theory are as compared to the others—all of this, of course, as his theory is taken to the Maxwellian EM limit. And, of course, how!
For engineers, it’s enough to know, first, what an electromagnetic theory of gravity (or a gravitational theory of electromagnetism) looks like—not quantum—and only then, second, how the complicating features due to the quantum nature smoothen out in the transition from QM to EM. And only then, third, what distinctive advantages that one theorization has in dealing with the complicating features due to the quantum nature, over some other theorizations. The treatment of course, being conceptual (or involving only the mathematics that engineers would be familiar with).
This way, engineers will at least be able to appreciate the intellectual effort involved in it all—even if it is just an “ex post facto” theory! 😉
Hope (at least) the nominees consider the request—or, perhaps, pick up the challenge!
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“The Green-Schwarz theory could be true —
It works for S-O-thirty-two!”
According to Motl, the Green-Schwarz theory and M-theory not only could be true but are actually guaranteed to be true. Motl might be correct. My main idea is that the monster group and the 6 pariah groups enable M-theory to have a computational method. If my main idea is wrong then I think the string landscape is empirically valid. I conjecture:
(A) Superpartners occur in nature if and only if nature is infinite.
(B) Some form of the string landscape is empirically valid if and only if nature is infinite.
(C) The main problem with string theory is that string theorists fail to realize that Milgrom is the Kepler of contemporary cosmology.
“The current standard model of cosmology (SMoC) requires The Dual Dwarf Galaxy Theorem to be true … the Dual Dwarf Galaxy Theorem is falsified by observation and dynamically relevant cold or warm DM cannot exist.” — Pavel Kroupa http://arxiv.org/abs/1204.2546 “The dark matter crisis: falsification of the current standard model of cosmology”, 2012
According to McGaugh and Milgrom, “MOND appears to be in good agreement with the observed velocity dispersions of the dwarf spheroidals of M31.” http://arxiv.org/pdf/1301.0822v2.pdf “Andromeda Dwarfs in Light of MOND”, Feb. 2013
According to Kroupa, Pawlowski, and Milgrom, “Understanding the deeper physical meaning of MOND remains a challenging aim. It involves the realistic likelihood that a major new insight into gravitation will emerge, which would have significant implications for our understanding of space, time and matter.”
http://arxiv.org/pdf/1301.3907v1.pdf “The failures of the standard model of cosmology require a new paradigm”, Jan. 2013
MAJOR CAVEAT: the email response from Witten (PUBLICIZED BY BROWN) applies to Brown’s FIRST POSTING ONLY and does NOT apply to this posting.
“One theory explains it all.” Are string theorists now the only physicists capable of evaluating the merits of string theory?
“… the string theorists in general will not attend lectures on experimental physics. They will not be terribly concerned about the results of experiments. They will talk to one another.” — Sheldon Glashow http://www.pbs.org/wgbh/nova/elegant/view-glashow.html
I have suggested that the alleged Fernández-Rañada-Milgrom effect and the Space Roar Profile Prediction are 2 decisive empirical tests for the hypothesis that the monster group and the 6 pariah groups enable M-theory to have a computational method.
Do dark energy and dark matter obey the equivalence principle?
Is there any experimental proof that dark energy and dark matter obey the equivalence principle? Is there any experimental proof that dark matter particles exist? Have string theorists failed to explain string theorists to experimental physicists?
“The process of learning what string theory is still has a long way to run. I don’t think we are close to seeing the end of it.” — Edward Witten, Newton Medal Ceremony, July 1, 2010
Einstein: Measurements show that inertial mass-energy equals gravitational mass-energy.
Brown: String theory might require a rethinking of Einstein’s equivalence principle. All measured mass-energy occurs on the boundary of the multiverse. All non-measured mass-energy occurs in the interior of the multiverse. For measured mass-energy, inertial mass-energy equals gravitational mass-energy. For non-measured mass-energy, the inertial mass-energy is always zero but virtual mass-energy that is not measured always has nonzero gravitational mass-energy. Dark energy has zero inertial mass-energy and negative mass-energy. Dark matter has zero inertial mass-energy and positive gravitational mass-energy. Is the preceding a meaningless farrago of verbiage? The alleged Fernández-Rañada-Milgrom effect might yield a decisive test.
http://vixra.org/pdf/1207.0049v1.pdf Gravity Probe B and the Rañada-Milgrom Effect
http://www.fqxi.org/data/essay-contest-files/Brown_spaceroaressay.pdf “Does Information Below the Planck Scale Explain the Space Roar?”
Is Milgrom the Kepler of contemporary cosmology? Are Milgrom’s acceleration law and the space roar the two main keys to unlocking the mysteries of string theory?
IF MILGROM WERE WRONG, THEN HOW COULD HE HAVE CONVINCED McGAUGH AND KROUPA?
“I was quite happy with the CCM, as everyone else …” — Pavel Kroupa http://www.astro.uni-bonn.de/~pavel/kroupa_cosmology.html Pavel Kroupa: Dark Matter, Cosmology and Progress
“… string theory is really a compelling candidate for a quantum theory of gravity …”
Does M-theory provide a way of explaining the flyby anomaly?
http://vixra.org/abs/1203.0036 “Does the Rañada-Milgrom Effect Explain the Flyby Anomaly?”
If X is to string theory as Kepler’s laws are to Newtonian mechanics, then what is X?
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