Sunday 25 August 2013

You can go faster than the speed of light

You can go faster than the speed of light.  This seems to be a strange thing to claim, because isn't the speed of light the ultimate speed limit?  It is, but speed only makes sense as relative to something else, and during an actual journey.  It's possible to have travelled faster than light, but only in a very special way.

Imagine you are setting off to the centre of the galaxy, about 30,000 light years away, and you have no limit to the amount of fuel you can use.  Suppose you travel with an acceleration of 1g to make it comfortable on your spaceship.  You could reach the centre of our galaxy in 20 years.  That's an average of 1,500 times the speed of light.

But no-one will actually see you travel at this speed because they will see you take about 30,000 years to reach the centre.  You won't see the distance to the centre of the galaxy as 30,000 light years as you are travelling because speed compresses length - it will appear very much shorter.  However, when you stop at the centre, you can, in hindsight, work out how far you have gone and how long it took.  You can travel faster than the speed of light so long as no-one sees you do it, not even you!

No comments: