When is it estimated humans will be capable of intergalactic space travel?
My guess would be about
The distances involved in intergalactic space travel would require some mechanism of Faster Than Light (FTL) travel to be accomplished in practical, useful time frames. Such mechanisms would tend to violate the principle of causality, so are unlikely to exist according to our current models.
Actually if a ship could achieve a sustained acceleration of
However, external observers in either galaxy would perceive the elapsed time as more than
Of course we could be less ambitious and travel to one of the much closer satellite galaxies of the Milky Way, a mere