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duckznutz · 06-04-2003, 12:42 PM

I guess I dont have your depth of knowledge on this subject so please forgive my ignorance . . . but : -

- If I am in a car going at 60mph in one direction and a friend is going at 60mph in the opposite direction then we pass at 120mph.
This is similar to one of us standing still and the other going past at 120mph . . or even one of us going backwards at 60mph and the other going past at 180mph . . .the relative difference is always 120mph because I disregard our 'actual' speeds relative to the ground and consider only our relative speeds.

So far so good . . now the bit where I get stuck . . if whilst travelling in one direction at 60mph I shine a torch forwards . . the light moves away from me at the speed of light REGARDLESS of my travelling speed . . the torch does not know I am moving.

My friend, travelling at 60 mph in the opposite direction, also shines a torch . . . now his light presumably also moves away from him at the speed of light? So the photons from my torch and the photons from his torch are moving away from each other at TWICE the speed of light PLUS 120mph . . . . . . . . . now I feel this is wrong becuase I believe the speed of light cannot be exceeded (is that right?) so whats going on there?

06-04-2003, 12:42 PM	#4 (permalink)
duckznutz Addict Location: Brook Cottage, Lanark, Scotland	I guess I dont have your depth of knowledge on this subject so please forgive my ignorance . . . but : - - If I am in a car going at 60mph in one direction and a friend is going at 60mph in the opposite direction then we pass at 120mph. This is similar to one of us standing still and the other going past at 120mph . . or even one of us going backwards at 60mph and the other going past at 180mph . . .the relative difference is always 120mph because I disregard our 'actual' speeds relative to the ground and consider only our relative speeds. So far so good . . now the bit where I get stuck . . if whilst travelling in one direction at 60mph I shine a torch forwards . . the light moves away from me at the speed of light REGARDLESS of my travelling speed . . the torch does not know I am moving. My friend, travelling at 60 mph in the opposite direction, also shines a torch . . . now his light presumably also moves away from him at the speed of light? So the photons from my torch and the photons from his torch are moving away from each other at TWICE the speed of light PLUS 120mph . . . . . . . . . now I feel this is wrong becuase I believe the speed of light cannot be exceeded (is that right?) so whats going on there? __________________ Where your talents and the needs of the world cross . . there lies your vocation.