Slowing Time - If a ship approached some significant portion of the speed of light, time slows down. This makes the trip seem shorter for the crew. These strategies suggest a one-way trip. Their civilization would be several generations further along than when they left it and all their friends dead. Volunteers for such an expedition might be few.
Current theory says no.
They might even permit intergalactic travel or travel across time. Such wormholes, if they do exist, most likely are fleeting, small tunnels that may not allow objects larger than a few atoms to pass. And they would only appear under the most exotic conditions. The technology that would allow the creation of a wormhole on demand that would be large enough to conduct a spaceship seems to be the realm of science fiction. A spiral galaxy.