05-23-2003, 11:16 PM
Hi,
Here is more of a philosophical poser for you. If time travel were possible, wouldn't someone from the future have come back to tell us.
J. Richard Gott wrote a very accessible book on time travel (Time Travel in Einstein's Universe"). One of the things he points out is that all time travel theories that have a decent physical basis require some form of "time machine" (e.g., a stretched wormhole, an infinite rod, moving crossed strings). The time travel is such that one can only go from sometime when the machine is in existence to some other time the machine is in existence (some of these machines permit only a given delta, others are continuous). Thus, time travel to *before* the machine is built is not possible.
I found Gott's book fascinating, especially his last chapter, "Report from the Future" where he discusses how to make predictions ;) Another nice discussion in that book is the time loop at the beginning, which makes the age of the universe both bounded and infinite.
As I said (and as you agreed), this is a fascinating topic, but one that requires some background or it devolves into error and/or fantasy.
--Pete
Here is more of a philosophical poser for you. If time travel were possible, wouldn't someone from the future have come back to tell us.
J. Richard Gott wrote a very accessible book on time travel (Time Travel in Einstein's Universe"). One of the things he points out is that all time travel theories that have a decent physical basis require some form of "time machine" (e.g., a stretched wormhole, an infinite rod, moving crossed strings). The time travel is such that one can only go from sometime when the machine is in existence to some other time the machine is in existence (some of these machines permit only a given delta, others are continuous). Thus, time travel to *before* the machine is built is not possible.
I found Gott's book fascinating, especially his last chapter, "Report from the Future" where he discusses how to make predictions ;) Another nice discussion in that book is the time loop at the beginning, which makes the age of the universe both bounded and infinite.
As I said (and as you agreed), this is a fascinating topic, but one that requires some background or it devolves into error and/or fantasy.
--Pete
How big was the aquarium in Noah's ark?