I’m a huge fan of Sci-Fi programmes such as Star Trek where they travel from star to star, trekking the universe in search of intelligent life. But one thing has always puzzled me. The Enterprise space ship seems to be able to jump from galaxy to galaxy in the blink of an eye, using warp drives which defy the laws of physics, as though it was doing a short haul flight from London to Newcastle. That’s just the thing. I know it’s just fiction, but it wouldn’t be possible to do that. Not for Kirk, Picard, Pike or any other commander you care to mention. That’s because, the laws of special relativity state that time and distance dilate the closer you get to the speed of light. This means that time for the Enterprise would not be the same for those back home.

Let’s say they want to travel to our nearest star Alpha Centurai. That’s about four light years away. If, and it’s a big if, the Enterprise’s warp drives could travel at 90% of the speed of light it would only take them 1.9 years to get there because, relativity shrinks time and the distance by about half. For those back on earth, 4.4 years would have passed. This means that, by the time the space ship got home on the return journey, those on the space ship would have only aged 3.8 years, but everyone on Earth would have aged 8.8 years. This ok at short distances, but when you think of Captain Kirk travelling to stars say 40 light years away, you quickly see that there would be few people left on earth to remember him when he got back, because he would have only aged around 40 years, but everyone at home would have aged more than twice that.

It doesn’t stop there though. Our galaxy is about 100,000 light years across, making it virtually impossible to explore. And, it gets even more mind boggling when you consider that our nearest galaxy andromeda is 2,500,000 light years away! For any being to be able to explore the universe, they would need to live for thousands, or even millions of years, or defy the laws of physics. So much for aliens visiting us. If they do exist, they must either live right under our noses, or they are so old that they probably set off for a nice visit to see the dinosaurs, only to find us glorified apes have taken over by the time they got here.

Finally, there is often talk of wormholes in sci-fi films, which are theoretical tunnels connecting two areas of space. The problem with these is that, if they exist, the laws of physics say the mouth of them would snap shut as soon as they are created. In any case, you wouldn’t be able to control where you were going, you’d just pop out in unexpected places. Hardly the plot of a good science fiction film. 

All this is saying that Captain Kirk couldn’t possibly warp drive around the galaxy and be back home in time for tea. He would be lucky to fit one long distance space journey in his lifetime. The science says it just isn’t possible, and if there were some way of extending our life long enough, or put us in deep freeze, none of our loved ones would be left alive by the time we got home. Space travel then, would be a very lonely business.

Source: time dilation calculator