Mathematical Obscurities in Special Relativity

Jan, What is source dragging? Can you describe this and where did the effect originate?

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Jim</i>
<br />Jan, What is source dragging? Can you describe this and where did the effect originate?
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This just means that we can imagine a photon to be a ping-pong ball that copies the velocity components of the source. For example, suppose I emit a laser pulse that hits a stationary mirror such that I receive the photon back at the point of emission. Now, source dragging means that when the mirror is translating with some velocity perpendicular to the photon's path, the photon will not return to the point of emission. The trajectory of the photon is therefore dependent on the motion of the source. I'm not talking about speed here.

The photon is reflected by the mirror but is that really a more complex process than it seems to be? Is it that the photon is absorbed by an atom and emitted in any direction other than directly back to the source? How is a photon reflected anyway? It seems lasers operate in much the same way with quite different effcets.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Jim</i>
<br />The photon is reflected by the mirror but is that really a more complex process than it seems to be? Is it that the photon is absorbed by an atom and emitted in any direction other than directly back to the source? How is a photon reflected anyway? It seems lasers operate in much the same way with quite different effcets.
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Yes, it looks like the photon is not reflected literally, but absorbed and another photon is remitted, thereby explaining the dragging.

But, the same thing is happening in the laser device so how does the photon changed or is it changed? The photon is always moving at the speed of light so any change would be redshift. It is quite a puzzle- don't you think?

The discussion now illustrates one of the problems in special relativity. People dont understand it. Many books teach that the velocity of light is source independent. But if you read Einsteins papers this is not mentioned. The main postulate asserts that the speed of light is independent of the observers "state of motion". So it is observer independent. All observers measure the same velocity even though they are moving relative to each other. This doesnt say anything about the velocity of the source.

I dont understand what is meant by source dragging. Is this an experimental fact?