05-29-2003, 02:04 PM
Hi, I'm a physicist. Sometime ago I was at a national physics conference where I listened to a review talk on the issue of time-traveling.
In a nutshell, time-traveling requires existance of wormholes. If Einstein's equations of General Relativity have wormhole solutions, there is in principle no theoretical obstruction to time-traveling. Einstein's equations are hard to solve, but as far as I know, there is no theorem forbidding wormhole solutions.
If time-traveling happens, you have a bunch of paradoxes in your hands, like for instance the `killing your grandpa before being born' thing. There are only two plausible ways out.
1. A wormhole is a gateway to another universe, so when you time-travel, you're also traveling between universes.
2. Wormholes simply don't exist and it is impossible to time-travel, period.
Well, nr.1 is a beautiful romantic thought, but most scientists believe nr.2 is the right answer.
So what could be the obstruction that forbids wormhole formation? The answer is not known, but there is a strong hint. General Relativity is a classical, large-distance theory of gravity. It does not explain what happens to gravity at short-distances. The theory of short-distance gravity is called `Quantum Gravity', but unfortunately no one knows what it is. By the way, the prize for finding it is immortality ;)
Nowadays, it is common belief among scientists that wormhole formation should get some obstruction from Quantum Gravity effects.
Well, that was it. Hope it's clear.
In a nutshell, time-traveling requires existance of wormholes. If Einstein's equations of General Relativity have wormhole solutions, there is in principle no theoretical obstruction to time-traveling. Einstein's equations are hard to solve, but as far as I know, there is no theorem forbidding wormhole solutions.
If time-traveling happens, you have a bunch of paradoxes in your hands, like for instance the `killing your grandpa before being born' thing. There are only two plausible ways out.
1. A wormhole is a gateway to another universe, so when you time-travel, you're also traveling between universes.
2. Wormholes simply don't exist and it is impossible to time-travel, period.
Well, nr.1 is a beautiful romantic thought, but most scientists believe nr.2 is the right answer.
So what could be the obstruction that forbids wormhole formation? The answer is not known, but there is a strong hint. General Relativity is a classical, large-distance theory of gravity. It does not explain what happens to gravity at short-distances. The theory of short-distance gravity is called `Quantum Gravity', but unfortunately no one knows what it is. By the way, the prize for finding it is immortality ;)
Nowadays, it is common belief among scientists that wormhole formation should get some obstruction from Quantum Gravity effects.
Well, that was it. Hope it's clear.