# Speed of light vs time

1. Dec 5, 2009

### krishnasrikar

1. As Einstein's theorem says "time slows down at the speed of light", does it mean that if humans travel at speed of light in future, time will slow down for the travelers as well.

2. If the above one is true, then would it mean that they would reach their destination quicker than assumed. For eg: suppose it would take around 4 light years to reach a 'X' star, would the traveler gets aged by 4 yrs or lower than that i.e. does time slow down.

3. Is time slowing down around the light particles (photons).

sorry for the grammar, i am not good in english.

2. Dec 5, 2009

### mgb_phys

Time stops at the speed of light, it slows down as you get faster.
it even works today at any speed. It's just that the effect becomes greater the faster you go.
If you cross the atlantic on concorde you age a few microseconds less.

Time passes slower for the traveller, if it takes 4years for an outside observer the traveller's watch would measure less time.

At the speed of light no time passes for a photon

3. Dec 5, 2009

### krishnasrikar

What happens when time stops.