- #1
birulami
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Trying to understand special relativity, in particular the influence of speed on time, I came up with the following picture, and wonder how accurate it could be.
Suppose a spell is cast on you in your rocket drifting through space that stops everything moving all over the rocket: from the arms on the wall clock, to the quartz in your watch, down to the molecules and atoms active in chemical reactions and even further to the subatomic level to whatever may jiggle and wiggle about, everything stops --- total "freeze". Just to be sure, the spell even stops photons just where they are. (Ok, this is unphysical, but a spell is anyway.)
Do you think you and your rocket are getting older, are aging now? Most likely not, because you are not changing, no chemical reactions that make wrinkles and grey hair in the long run.
Do you think time passes in the rocket now? Tricky. To my knowledge there would be no way to prove that time passes, because everything came to a halt: no change, no way to measure time passing. Why not extend this a bit and say: "Without change, no time passes". Or even stronger: time *is* change.
If we can assume this for a moment, an interesting connection to special relativity appears. Suppose after releasing the above spell, another spell accelerates you and your rocket to the speed of light. Would you and your rocket still be able to change? No, because in addition to your forward motion the change would require additional velocity components for, say, the molecules to perform their chemical reaction. But the additional velocity is not available: speed of light cannot be topped. The situation at the speed of light is very much the same as described for the original spell: (relative) change of any kind within your body or the rocket is not possible. Consequently no time passes.
No need to say that this argument goes smooth for rockets slower than light if we assume that atomic and subatomic changes like chemical reactions require exchange of photons and similar "particles". These are going along with the rocket and only what is left towards the full speed of light can be invested in change. The faster you go, the lesser is left for change, i.e. for time passing.
As a side note we realize that in this picture time is a completely local phenomenon.
Does this picture have any credibility?
Suppose a spell is cast on you in your rocket drifting through space that stops everything moving all over the rocket: from the arms on the wall clock, to the quartz in your watch, down to the molecules and atoms active in chemical reactions and even further to the subatomic level to whatever may jiggle and wiggle about, everything stops --- total "freeze". Just to be sure, the spell even stops photons just where they are. (Ok, this is unphysical, but a spell is anyway.)
Do you think you and your rocket are getting older, are aging now? Most likely not, because you are not changing, no chemical reactions that make wrinkles and grey hair in the long run.
Do you think time passes in the rocket now? Tricky. To my knowledge there would be no way to prove that time passes, because everything came to a halt: no change, no way to measure time passing. Why not extend this a bit and say: "Without change, no time passes". Or even stronger: time *is* change.
If we can assume this for a moment, an interesting connection to special relativity appears. Suppose after releasing the above spell, another spell accelerates you and your rocket to the speed of light. Would you and your rocket still be able to change? No, because in addition to your forward motion the change would require additional velocity components for, say, the molecules to perform their chemical reaction. But the additional velocity is not available: speed of light cannot be topped. The situation at the speed of light is very much the same as described for the original spell: (relative) change of any kind within your body or the rocket is not possible. Consequently no time passes.
No need to say that this argument goes smooth for rockets slower than light if we assume that atomic and subatomic changes like chemical reactions require exchange of photons and similar "particles". These are going along with the rocket and only what is left towards the full speed of light can be invested in change. The faster you go, the lesser is left for change, i.e. for time passing.
As a side note we realize that in this picture time is a completely local phenomenon.
Does this picture have any credibility?