Question on colours

[Boerseun]

If you backed away from a lightsource at 99.999 c, then the light will still pass you at c (although redshifted to hell and gone). For an observer in another frame, it'll seem as if the light's passing you at 0.000001c. The reason for this is that you'll experience time dilation to such an extent that the observer's 0.00001c will seem to you the same as c.

[Torson]

My apologies for clouding the issue!!

 

Make no mistake, Special relativity says:

 

1. The speed of light is the same for all observers, no matter what their relative speeds.

2. The laws of physics are the same in any inertial frame of reference. This means that the laws of physics observed by a hypothetical observer travelling with a relativistic particle must be the same as those observed by an observer who is stationary in the laboratory.

 

My mistake from the start was to confuse the speed of light with the frequency of light, i.e. the wavelength and its amplitude travelling. That’s why I used the wave along a rope, but should have said: backing off at the speed of the amplitude travelling speed. If I back off at the same speed as one particular amplitude, I will not see the light. If I am standing still relative to the source of light, I will experience the same colour of light as the source. If I back of at a certain speed the amplitudes will not reach me with the same frequency and we have what is called a red-shift, i.e. I will experience a light with a lower frequency (colour). In this case the speed is relative.

Again, I’m sorry for confusing physics!

[cwes99_03]

The answer has to do with the word transparency.

 

To be transparent, then light has to be allowed through. Therefore, one can still measure some light from all frequencies making it through. The reason the object appears to be red, and light traveling through it and then reflecting off of a white surface seems to be red is that this particular frequency of light is reflected (perfectly?) by the atoms in the transparent material. Our sky does much the same thing, though through a slightly different process than by electron scattering. However it is so transparent that only some of the blue is reflected (scattered) by the atoms in the atmosphere. Thats why the sun still largely appears white/yellowish.