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Project Insomnia

Project Insomnia is many things, but in this context it is simply a "braindump" of whatever I happen to be thinking/reading/watching/doing at the moment. Parental guidance suggested.

Wednesday, October 29, 2003

Individual Luxury String-ettes

This month's Scientific American excerpts a fascinating interview with physicist and best-selling author of The Elegant Universe, Brian Greene. The full interview is available on Scientific American's Web site.
Image: NOVASA: In the case of relativity, you had the equivalence principle and general covariance in that beacon role. In the Standard Model, it's gauge invariance. In The Elegant Universe you suggested the holographic principle could be that principle for string theory [see also "Information in the Holographic Universe," by Jacob D. Bekenstein; Scientific American, August]. What's your thinking on that now?

BG: Well, the past few years have only seen the holographic principle rise to a yet greater prominence and believability. Back in the mid-'90s, shortly after the holographic ideas were suggested, the supporting ideas were rather abstract and vague, all based upon features of black holes: Black hole entropy resides on the surface; therefore, maybe the degrees of freedom reside on the surface; therefore, maybe that's true of all regions that have a horizon; maybe it's true of cosmological horizons; maybe we're living within a cosmological region which has its true degrees of freedom far away. Wonderfully strange ideas, but the supporting evidence was meager.

But that changed with the work of Juan Maldacena [of the Institute for Advanced Study in Princeton, N.J.], in which he found an explicit example within string theory, where physics in the bulk--that is, in the arena that we consider to be real--would be exactly mirrored by physics taking place on a bounding surface. There'd be no difference in terms of the ability of either description to truly describe what's going on, yet in detail the descriptions would be vastly different. One would be in five dimensions, the other in four. So even the number of dimensions seems not to be something which you can count on, because there can be alternative descriptions that would accurately reflect the physics you're observing.
I have been reading SciAm since I was young--my father has had a subscription for years and I bought newsstand copies and eventually subscribed on my own. I read Greene's book a couple of years ago, and when I finished, I promptly began again from the beginning. It takes a few times through to wrap my mind around the concepts he so deftly explains.
|| Andrew, 9:05 PM || ||

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