Quote:
Originally posted by John Henry
Although I accept the physical theory behind the atomic clock experiment, I am uncomfortable with the fact that the measurements taken were on such a small scale. If the difference was only nanoseconds, assuming this is within acceptable error for atomic clocks and that the experiment was proven to be rigourously repeatable, how do we know that the difference could not be accounted for by other effects of the differences in environment of the two clocks
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First of all, two synchronised atomic clocks deviating by (say) 80 nanoseconds in the course of a few hours is a HUGE divergence given that they are usually accurate to one second in 20 million years.
Second of all, the theory doesn't predict that there will be "some" undefined divergence. It predicts very precise amount of divergence, and the these predicted results have been verified to be accurate to an extemely high level of precision. It would take one hell of a coincidence for a "random" deviation due to the effects of the environment to line up so perfectly with the predictions.
Thirdly, this experiment is not a once off thing. Relativity has been rigorously tested, and the theory has spectacularly held every time.
Fourth, relativity is a
practical working theory, much the same as Newtonian mechanics. Relativistic effects have to be taken into account by NASA. Think about how GPS works. The satelites orbiting about the earth need to know precisely where they are. This requires their on board clocks to be
precisely synchronised with earth time. The computers on board are programed to peridically readjust their clocks, to account for the relativistic divergence. (clocks on satelites are under a weaker gravitational field than those on the earth's surface).
Fifth, relativity also predicts other effects, than those to do with time. Most famously is the fact that we can see a star which should be obscured by the sun due to the bending of the light rays as predicted by general relativity.
links
Will an atomic clock on the International Space Station be slower than a synchronized atomic clock on the ground?
What is the experimental basis of Special Relativity?
Relativity Tutorial
This page looks good. I didn't read it, but it looks as though it will give a good solid, introduction to relativty, that it reasonably simple to understand.