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Posted by yelmalio/">yelmalio on January 17, 2000 10:52:06 UTC
1. Could someone please explain to me what a white hole is, on some forum, maybe this one I heard something about it and i'm not sure if i understand.
Its the exact opposite of a Black Hole. According to theory the singularity at the center of a Black Hole could be connected via a "wormhole" to another region of spacetime. This wormhole is called an Einstein-Rosen Bridge and should not be confused with wormholes arinsing from quantum theory. Whereas spacetime in a Black Hole is tightly curved so that everyhting stays inside the event horizon, spacetime in a White Hole is curved away from the singularity.
The idea is that everything that falls into the black hole comes out at a white hole. The lack of observational evidence for these white holes implies they are only theoretical and not practical.
2. Could you explain how wormholes could be used for time-travel?
Definitely read Kip Thornes book, "Black Holes and Time Warps, Einsteins outrageous legacy". It's all about this topic. It's been a while since I read the book and this theory, I'll try and summarise correctly. If I get it wrong, I'm sure some one will correct me.
According to theory, some evidence for it as well, the space around you is a quantum foam. That is, virtual particles and 'wormholes' are being ceated all the time. These wormholes are tiny points conecting two neighbouring points in spacetime. They have the property that if you could enter one you would emerge at the other end simaltaneously. These things are tiny, less than 10-33 meters and exist for an equally short time, less than the planck length and time.
The trick is to artifically create a wormhole, hold it open, make it big enough to physically enter and take one end away in a spacecraft. Where the space craft lands that end of the wormhole is caually connected to the other end. Go into the wormhole and you come out the other end instantaneously. This is a form of time travel.
Its a given that the technology required to pull this stunt is so far advanced than our it would be indistguishable from magic. The energy requirements are also enourmous. You would need the entire energy output of a large star to do this.
if somehow we let loose of whatever it is that is holding us still in the fourth dimension, and just went along with the flow of time, would it have no effect on us? I guess this isn't exactly a theory, but just my thinking... you can reply to it however you want, or not at all.
One of the big points about relativity is that space and time are indistguishable as spacetime. If you move through space you move through time. How you move through space effects how you measure time. We are not stationary in the 4th dimension, it moves with us always. To illustrate the point, one of the reasons time appears to slow down near a black holes event horizon is that space is highly curved. If you change the space-like part of a Minkowski spacetime manifold it alters the time-like part by making time run slower.
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