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If I have this right (which I probably don't!) photons travel at the speed of light in a vacuum (well, I suppose they'd have to, seeing as they are light!)Now, I think that means that, from the photon's perspective (not that it really has a perspective - maybe it does?) it arrives as soon as it leaves. It experiences no time between it's departure and arrival, so, from its perspective it is the same "age" when it arrived as the age it was when it left, in other words, it did not age. - Phew!
However, when light travels through anything other than a vacuum, it slows down (I think). If that is true, then the photon does age when it is not travelling in a vacuum.Does this ageing effect the photon in any way, or does it have no effect at all?
I think it is safer to say that time has no 'meaning' for a photon. But, as it has no consciousness, then the word 'meaning' has no meaning in that context.Whilst the sort of analogies used to illustrate some aspects of Physics can be useful, it is important to go back to the original theory, rather than to try to extrapolate using an over simplified idea before jumping to conclusions.
LeeE,Point taken. Then, if electrons had some decay characteristic (and, before everyone jumps down my throat, I'm not suggesting they actually do ), if I understand you correctly, the amount of decay would in some way represent the "age" (for want of a better word) of a photon?
Well, if you think in terms of space-time, it's movement........
So how is one supposed to point out when a statement seems to be inadequate?Stop taking offense and try to justify what your wrote. It would be a more fruitful line of argument. If you had told me I was working to a simplistic model then I would have looked again at my model and not been offended. The last thing I would have done would have been to feel 'insulted'. I'm far too interested in improving my understanding.Do you not take my point about the risk of over extending analogies? Perhaps you could give me a form of words which would have got the idea across without getting you so cross. I'm sorry; I really didn't mean to.
I think it's unwise to assume that the rules that apply to objects with non-zero rest-mass also apply identically to objects with zero rest-mass.Objects with non-zero rest-mass cannot achieve 'c' but time-dilation is only observed in objects that have non-zero rest-mass and although the rate of time approaches zero for a non-zero rest-mass object as its speed approaches 'c', we also know that it can never actually achieve 'c'. Thus, the assumption that no time passes for a zero rest-mass object traveling at 'c' is flawed, imo - it is based upon the characteristics and rules of something totally dissimilar.
Lightarrow, that is a very interesting point. A related question: I'm assuming that the relative motion to which you refer is independent of any spatial expansion,
Quote from: Geezer on 29/08/2009 16:56:01Lightarrow, that is a very interesting point. A related question: I'm assuming that the relative motion to which you refer is independent of any spatial expansion, Sorry, can you explain better what you mean? If you can, use an example.
I think what Geezer means is that does the movement of everything away from each other due to the expansion of the universe count as relative motion?For example, if the expansion of the universe means that the speed of recession at distance d from Earth is x, and we launch a rocket from Earth that maintains a velocity y against gravity, when it reaches point d is its velocity relative to us x + y?