Science Forums 2

[CraigD]

Originally Posted by Agen

How about distant galaxies then? Those, which have a relative velocity of near c to us.

The time dilation for objects at nearly opposite sides of the visible universe would be pretty dramatic, though still not, I think, a big problem.

The greatest observed redshift are on the order of z=7, which corresponds to a distance of about 4 billion parsecs, a few thousand times the radius of the Local Group. Hubble’s law, which is widely believed to give accurate estimates at all distances in the observed universe, gives a recessional velocity for such a very distant body of about

, corresponding to a time dilation factor of about .

Originally Posted by Agen

Wouldn't exploring those be a problem?

Exploring even nearby stars certainly pose huge problems, doing so via wormholes even more so, because while we’re confident that propelling spacecraft to distant stars is theoretically possible, and have some practical engineering experience with how to go about doing it, we’ve no theoretical confidence that traversable wormholes can exist, and only the vaguest hunches about how one would create and/or traverse them.

Much of what we know, we know because of the efforts of Kip Thorne and friends to help the late Carl Sagan write as scientifically plausible a novel as possible in which characters travel quickly to and back from a place near our galaxy’s center. While the result, 1985’s “Contact”, is arguably the best scientifically researched science fiction novel written, the theoretical work that went in to it is very speculative, and far from any claim of scientific plausibility. This is not to say that such a thing isn’t possible, only that a lot of scientific work is needed before we can even say with much confidence whether it is or not.

If space travel via wormholes is possible, best theory strongly suggests that any wormhole couldn’t be “dug” faster than the speed of light. Like the subway train system SF stories commonly describe them as like, if possible, such systems would likely take a very long time to build – the reason why much good SF, such as “Contact”, tells tales of humans finding such systems already built by ancient civilizations, rather than building them ourselves.