"The future ain't what it used to be."

#### Keven

##### Temporal Novice
My friends are trying to convince me that light has a definite mass, a very small one but a mass none the less. I know they are idiots and don't have a clue what their talking about but, they don't believe me, even though I have proven it many times.

Any ideas of any facts/formulas I can use to convince them for sure?

Light has mass it just doesn't have rest mass.

Objects which are moving have their mass increased by a factor of 1/sqrt(1-v^2/c^2). For light this is 1/sqrt(1-c^2/c^2) = 1/0, which is infinity (sort of).

In order to work it out you have to solve for energy. The mass of each photon is determined by E=mc^2 = hf. So m=hf/c^2. This can be seen experimentally by shining a flashlight at a mirror attached to an object that is sliding with very little friction. The momentum of the light will cause acceleration when it hits the mirror.

Then could you use this as a power source (not solar), like in sapce where there is litle friction, jsut shine a big light and be propelled away from it?

Wasn't that ised in a movie once? And of course being me, I relate everything to movies.

There was a light thing that corrupted people with power, on an asteroid, a mining place.

they travelled on light beams super fast. they had to go into chambers in order not to melt, at the end 2 people share a pod, they change half eye color... whats the movie name? arg!

keven: yes, solar sails.

i belive the movie was "Supernova"