#### Page authors

• Allen Versfeld
October 12, 2011

### What is the speed of light?

 The official definition of the speed of light in a vacuum is c = 299 792 458 meters per second.  To help you make sense of this, here are some other ways of describing this:  Light travels at just over a billion kilometers (or 600 million miles) per hour. If you could make a beam of light curve, and sent it on a trip around the Earth, it would make the journey 7 times in under a second.  It takes me a little over 6 hours to drive from my home in Centurion to the coast at Durban.  A beam of light makes the trip in two thousandths of a second.  The universe is built in such a way that there is an absolute maximum speed - it is physically and literally impossible for anything at all to move faster than that speed.  The only thing that travels at that speed is light. However it is possible to make something go faster than a beam of light.  Light travelling through something other than a vacuum (air, water, glass, etc) travels at a lower speed.  If you find the right material, you can slow light right down.  If you can travel faster than this new speed, without exceeding c, then you can technically claim to have traveled faster than light! Comments?  Questions?  Why not mail me at uastronomer@gmail.com