# Change in speed of light

1. Nov 27, 2012

### paras02

Hello!
if a car(A) is moving with a speed 2m/s and another car(B) is moving in opposite direction with speed 3m/s. then velocity of car(A) with respect to (B) is 5 or -5m/s .
so my question is why the same principle does not follow with speed of light as according to theory of relativity speed of light remains same from every frame of refrence ?
or i can say that if i move with a speed c/2( c is the velocity of light ) opposite to the direction in which light is propogating the velocity of light w.r.t me will be 3v/2 or -3v/2.
Isn't this true?

2. Nov 27, 2012

### Staff: Mentor

3. Nov 27, 2012

### phyzguy

Simply put - that's not the way our universe works. Feynman said, "You don't like it? Go somewhere else!"

4. Nov 27, 2012

### lightarrow

Actually, the law is the same . It's only that you didn't know which is it:

V = (v1 + v2)/(1 + v1*v2/c2).

Now put 2m/s as v1 and 5m/s as v2 and compute V.
Then do the same with v1 or v2 or both, equal to c = 299,792,458 m/s.

--
lightarrow

5. Nov 27, 2012

### paras02

thankyou guys