Do wormholes actually exist and can they be used for time travel?

[doc.madani]

How is time travel possible? i understand that we can warp and modify time but i don't understand the concept...


Is there any evidence to suggest that there are wormholes? if so how are they created?

 

[qraal]

How is time travel possible? i understand that we can warp and modify time but i don't understand the concept...


Is there any evidence to suggest that there are wormholes? if so how are they created?

Time-travel - backwards in time - becomes possible when closed time-like curves around large masses are formed. Travelling in certain circular paths around the mass also means travel backwards in time. Cosmic-strings are one 'natural' object around which closed time-like curves might form.

Another possibility is when a wormhole pair (two connected 'mouths') is produced and one mouth travels to the distant Universe and returns at high speed. A time difference is created between the two because of relativistic time-dilation creating a difference in the flow of time between them. But there's a catch - aside from the difficulty of making wormholes, the time difference is created by traveling a very long way if you want a large time difference between the mouths. Also the difference is fixed - unless a mouth goes traveling again, the difference isn't changed.

Both possibilities are allowed by General Relativity, but neither has any observational support and presently we don't know how to make a pair of wormhole mouths. Virtual mouth-pairs are believed to be created in the quantum vacuum, but there's presently no way of knowing if this is so, as we don't have a quantum gravity theory of the vacuum that is supported by any observational data. Other vacuum theories exist, for example the Stochastic Electrodynamics theory, and these don't have virtual wormholes.

So that's our present state of knowledge - lots of ideas, but very little data.