Just looking at common SciFy problems on Facebook and we came up with Ten while most are answered here better than in other places one caught my attention.
9) You can travel at the speed of light and no time passes elsewhere
If you do manage to travel close to the speed of light, the time dilation effects should be huge, says Kakalios. To the point where a few days traveling at light speed should mean that hundreds of years for the rest of the universe. When DC Comics had Supergirl appear in the 31st century in Supergirl and the Legion of Super-Heroes, and everybody was asking how Supergirl had traveled forward in time 1000 years, Kakalios actually emailed writer Mark Waid, suggesting that Supergirl could have been chasing a Dominator at light speed for a few days. That, by itself, would cause 1,000 years to pass. Waid responded that that was way better than what he'd come up with on his own, which was a rogue Zeta beam. This is something that science fiction stories "have to get wrong," says Kakalios, "unless you specifically wanted to fold time travel into the future into your story." And if you go backwards to your destination at light speed, it's not like the odometer rolls backwards — you just go further forward in time.
With all the Minutes on Days spent at near Light speed, even 80% of light speed, time Dilation should cause those speeding along to be out of time more that anyone else. Let alone what hyper space would do.
Is there an 80% of light speed rule in Hyperspace? Given that there is no matter in Hyper space you likely would be able to go very fast. However doing so for a few days you would miss centuries when you got back home.
One other question that arose was how ships communicate in Hyper space with each other?
