# Question of Relativity and the Speed of Light?

1. Jan 29, 2012

### WLatourelle

Is there an equation to figure out how much time would pass traveling light speed for 10 years relative to the person traveling? I know its less, but by how much exactly?

2. Jan 29, 2012

### ghwellsjr

Yes, the equation is τ=t√(1-β2) where τ (tau) is the time for the traveler, t, is the time in the stationary frame, and β, beta, is the speed you want to travel as a fraction of the speed of light and can have a value from 0 up to but not including 1 (which is the speed of light). If you pick a speed of 1, then you get the same answer no matter what t is which doesn't make any sense. But pick any smaller value and you can use the equation. This equation was published by Einstein in his famous 1905 paper introducing Special Relativity near the end of section 4.

3. Jan 29, 2012

### WLatourelle

Thank you, that is just what I was looking for. But just to be clear it doesn't make any sense to input the speed of light and above because it's thought impossible to reach, correct?

4. Jan 29, 2012

Correct.