Saturday, September 23, 2006

To String Along or Knot

I have long been an advocate of underdogs and unpopular positions in politics, science and life. But in graduate school I was attracted to the hot new field of quantum optics, partly by the excitement over the laser, also the development at Rochester of a laser fusion lab and the renown of two physics professors in the quantum optics group. Emil Wolf (of Born and Wolf fame) and Leonard Mandel came to Rochester in the early 60s as part of the brain drain from Britain. Both men were outstanding teachers and theorists, and Mandel was one of the unique scientists equally at home in both theory and experiment.

So I jumped into this very popular pool, failed as an experimenter, and finally finished a theoretical thesis on an extension of the superradiance theory originated by Robert Dicke at Princeton. I was so happy to be done that I barely noticed whether my work made the slightest ripple on the vast turbulent ocean of theoretical physics. It didn’t. Much later I looked for references to the four published papers that went into my thesis, hoping at least for a quantum perturbation in the physics literature or a fluctuation in the vacuum background, or … whatever. Apparently the uncertainty principle bit me since I found the appropriate papers but mention of my work couldn’t be localized.

Right after college I had a stroke of personal and scientific luck. I was introduced to industrial research at Xerox by an iconoclastic fellow named Chuck Gallo, who 30 years later talked me into the quasar work I wrote about in the last post. Chuck’s advice was to avoid the popular fields and try to do something important in a field with less competition. He pointed to the hordes of solid state physics PHDs at Xerox who were working on aspects of xerographic photoconductor physics using the theories they learned about crystalline solids while the xerographic materials were decidedly amorphous. What a waste of time that was. Anyway, I followed Chuck’s advice and am quite glad I did.

Which brings me back to the subject of the last post and the question: Whether it is better to string along with the popular string theorists or to look elsewhere? Having little detailed knowledge of the contenders, no ax to grind, and an iconoclast’s disposition, I think I am ideally qualified to assess the contest. Plus, it’s my blog.

One of the benefits of Mahndisa’s Thoughts is the many collaborators who link to her blog. Lubos Motl of The Reference Frame blog is one of the stringy advocates. I liked his credo: “The most important events in our and your superstringy universe as seen from a reactionary physicist’s viewpoint.” Lubos sounds like a guy I‘d enjoy having a beer with.

On Sept. 19 Motl posted “Requisites for writing about cutting-edge physics” that takes apart an article by pizza delivery boy, now science writer, Dan Vergano.

Vergano was bold enough to write a piece called “String theory: Hanging on by a thread?” in USA TODAY (9/19/06). His lead paragraph continued the attack: “String theory is on the ropes. After decades of prominence as the key to physics' elusive theory of everything, challengers say the hypothesis is unraveling.”

Lubos objected, numerically: “1503 people will notice that it is nonsensical to say that a theory can be unraveling because it has not yet been proven.” I agree, hyperbole is breaking out all over in popular accounts of global warming, bird flu, murderous black holes, … plague, pestilence …

Vergano is a little loose with the facts when he states that the standard model of particle physics links “electromagnetic and atomic forces by showing they all result from the interactions of fundamental sub-atomic particles. These point-like objects with whimsical names like quarks, leptons and bosons are the building blocks of atoms, according to the standard model.”

More precisely the standard model accounts for three of the basic forces of nature (electromagnetism, the strong nuclear force and the weak nuclear force, but not gravity) and the two classes of elementary particles, quarks (6 kinds) and leptons (6 kinds). Where are the fact checkers when you need them?

Vergano continues with the observation that the force of gravity described by general relativity, “remains distinctly divorced from the standard model, a quandary that has long troubled physicists because the two theories differ greatly in their visions of how the universe functions and fits together. This suggests that both fundamental theories are fundamentally flawed, say (Lee) Smolin and others.”

Motl replies with another numerical argument: “1105 readers will know that the incompatibility of two principles doesn't mean that both of them must be wrong.”

True enough, but they are at best approximations. For example, general relativity runs into trouble inside a black hole where the strength of gravity becomes infinite, widely believed to be an artifact of the neglect of quantum effects in the theory.

Lee Smolin has criticized string theory as a mathematical effort like quantum electrodynamics to solve a problem that belongs in the realm of basic theory, such as general relativity. He sees a historical warning in Lord Kelvin's ancient idea of "knot theory," that atoms are essentially knots in the mysterious aether. Kelvin's concept was popular for decades until Einstein demolished the aether itself.

I think the reference to knots is a bit far fetched but it is fair to say that the unification of quantum theory and general relativity needs more basic understanding and somewhat less fancy math. We need a Newton, Einstein or Heisenberg rather than a Feynman, Gellman or Motl. (with all due respect, Lubos)


Blogger Mahndisa S. Rigmaiden said...

09 24 06

Hello Bill: I wanted to say thanks again for sharing a bit about yourself. I believe that by reading your story, it has given me the clarity that I need at this time. Thanks:) I wanted to let you know that your link to Lubos doesn't work, I think you forgot the period after motls:

Yes Lubos is a controversial character, but some of the stuff he says about crackpot theories are on point while some of his other stuff is just opinionated bs, sorta like my blog;)

Regarding what is happening with LQG and string theory, only experiment will tell...I personally like the idea of discretized spacetime, but the idea of strings makes sense too. In one paper by Thomas Thiemann, he quantized the Nambu Goto string under LQG assumptions. There were some issues with the final energy spectrum being unbounded, except for the ground state. But inequivalent representations of the CCR still can lead to physically meaningful results. So I am curious to see how all of this will unfold.

In the meantime, I am into p adic physics and fractals. hehehehe Have a wonderful rest of weekend!

2:32 AM  
Blogger Mahndisa S. Rigmaiden said...

09 24 06

Before I go Bill I wanted to provide you with links to two papers of opposing viewpoints:

1.Thiemann. T. The LQG -- String: Loop Quantum Gravity Quantization of String Theory I. Flat Target Space. 23 Jan 2004.

2.Helling, Robert C. Policastro, Guiseppe. String quantization: Fock vs. LQG Representations. 17 Sept 2004.

I think this would provide you with a balance in perspective and both are rigourous but well written:)

2:37 AM  

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