Velocity and recessive velocity

dracobook
What is the difference between velocity and recessive velocity. I read that with velocity, an object may not past the speed of light; but with recessive velocity, an object may past the speed of light.

Homework Helper
Gold Member
There's no difference. "Recessive velocity" or "velocity of recession" just refers to the velocity of some object moving away from the observer. The opposite would be "approaching velocity" or "velocity of approach", for example.

The speed of light is a limit on the speed of an object in space, whether an object is coming towards you or going away. However, maybe you are thinking of the expansion of the universe, in which space itself expands, carrying objects such as galaxies along with it. The expansion of space, as opposed to the movement of objects in space, is not limited by the speed of light.

dracobook
thanks James R. Yeah I was thinking of the expansion. I also have another problem. Well, according to relativity (I think) the speed of light is the same for all reference points. So, imagine if you willl, that you are a particle of light. You are traveling in a straight line from point A to B and another particle of light is traveling parallel and in the same direction as you. According to relativity, wouldn't the second particle of light be traveling ~3*10^8 meters per second relative to you? Wouldn't this happen if the object was traveling parallel yet in the opposite direction as well? ..:( I don't think I understand relativity very well..