Wikipedia attribution link for Calabi-Yau diagram.
Thursday, November 10, 2011
Brian Greene continues "The Fabric of the Cosmos" with "The Illusion of Time" and String Theory
Wednesday, PBS presented the second evening of episodes, 2 of them, from “The Fabric of the Cosmos”, narrated and hosted by a handsome Brian Greene, author of “The Elegant Universe”.
The first was “The Illusion of Time”, link here.
The show focused on the way gravity affects time, and that time slows down around massive objects. A space voyager near a black hole would age much less rapidly, and seem to have traveled into the future when he returned.
The equations of physics would normally apply if time moved in either direction. But in real life we experience a “time arrow”. Travel back to the past (“Terra Nova”) might be possible, but it wouldn’t allow us to do anything to change history and produce contradictions. Why? The main principle seems to be entropy, which always increases. In fact, the universe has increased in entropy from the initial singularity. Reversal of entropy in the short term requires “work” and the expenditure of energy.
Entropy may explain the “tree of life”. An individual organism must age and decay because of entropy. Reproduction is the most efficient way to do the “work” of reversing entropy and allowing consciousness to be expressed in another future being. A Messiah would seem to be the exception, hard to explain in terms of physics. A good question would then be how “angels” (immortal) could exist. Some sort of energy, maybe related to moral karma, would be necessary to prevent gradual decay.
Eventually, in some quadrillions of years, the universe will have so much entropy that time as we know it will cease to pass. Does the Christian Heaven really promise eternal life?
The second hour appeared to be based on an earlier episode of “The Elegant Universe”. It was “String Theory: A Theory of Everything”, link here.
This program concerned the effort, well underway in the 1980s, to explain the four forces: string nuclear, weak nuclear, electromagnetic, and gravity. Gabrielle Veneziano had discovered major equations as a young graduate student in 1968, and professors at Stanford (Leonard Susskind) and Texas worked for decades on the math. Ultimately, all matter comes down to the tiniest possible strings of vibrating stuff, with the mathematics requiring eleven dimensions. An extra dimension might be what an ant experiences walking around a Venetian blind cord (before it has wings).