2cars moving slightly less than speed of light look faster than light to each other?

1. Aug 26, 2011

AgentPancake

if the cars are moving towards each other.

Last edited: Aug 26, 2011
2. Aug 26, 2011

Hootenanny

Staff Emeritus
Re: 2cars moving slightly less than speed of light look faster than light to each oth

No. The speed of light doesn't change no matter how fast you are moving. Light will always move away (toward) you at the same speed, c. This is a consequence of principle of relativity*.

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(*) Often people will say that this is a postulate of special relativity. However, it is possible to derive the constancy of the speed of light simple from the principle of relativity.

3. Aug 26, 2011

tiny-tim

Last edited by a moderator: Apr 26, 2017
4. Aug 26, 2011

jewbinson

Re: 2cars moving slightly less than speed of light look faster than light to each oth

Interesting.

So suppose your friend's spaceship is moving towards you at 0.9c.

Then after 1 second he would have moved 0.9C and the light from 1 seconds ago will be 0.1C infront of where he is now. When the light reaches you, your friend would have moved closer to you, but still I can't (immediately) see how any rules can be broken by this model.

Anyway, is my understanding correct?