Quote:
Originally posted by iamtheone
If light is travelling at 'light speed' C within the Universe, and the Universe is moving in direction A, then light moving within the Universe along the line of the Universe' travel - A - would be travelling at C + A, therefore, faster than light speed......?
And any travelling in the opposite direction would be C - A...therefore less than light speed......?
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No no no no no.
That is wrong.
The situation you describe is incorrect for a variety of reasons.
1. The speed of light is constant therefore it does not change no matter what inertial frame it is it. Example:
There is a high speed train with a laser emitter mounted on it. It fires a laser at a sensor which measures speed. Then a person standing still on the ground fires a laser at the same sensor. The speed of the laser is still the same even though the train is moving very fast towards the sensor. The situation is true if the train is moving away from the sensor as well.
2. The situation you describe is putting the universe in a inertial frame and comparing it to an inertial frame outside the universe which does not make sense because it cannot be done.
Now to answer d3f1's question:
The equation for time difference is this:
∆T = ¥T
T is the relative time and ¥ is 1/squareroot( 1- beta ) and beta is velocity/speed of light or v/c.
Light travelling at c would make beta equal 1 which would make the denominator of the equation equal to zero making the functions undefined. This means that the time for light cannot be defined. And as tecoyah said, light is a photon and carries no mass and it is unlike anything else in the universe.