Question: Can you bend space by traveling at light speed?

Sam Connolly answered on 23 Jun 2014:

It depends what you mean by bending space – it’s more like squashing space! Heavy objects, with a lot of gravity, can bend space, so that something that would normally go in a straight line in space has its path curved around, which is how you get things in orbit around planets and stars. Moving very fast is a bit different though. What happens is very strange and all because of Einstein’s theory of relativity, which says that light always goes at the same speed, no matter what speed the person measuring it is going at, which is different to normal things. If, for example, you measured how fast a car was going when you were standing still on the road as it passed and it was going at 60 miles per hour, then you measured it while you were driving in a car as well, going at 20 miles per hour behind the other car, you would only measure the other car as going at 40 miles per hour. But this doesn’t happen with light! You would always measure it as going at the same speed! And because it doesn’t, it means that so that everyone’s speed measurements match no matter how fast they’re moving, time and space get stretched or squashed depending on how fast whatever they are looking at is going. If you were driving close to the speed of light in a car, then your car would look its normal length to you and time would be passing normally, but for someone who isn’t moving compared to you, your car (and you!) would be squashed up in the direction you’re travelling (called ‘length contraction’) and if they looked at your clock whilst you want past they would see time passing more slowly for you (called ‘time dilation’). It’s a bit confusing and complicated! But hopefully that makes a bit of sense?!