Re: Confirmation of Relativity

[Ken Caviness <caviness@SOUTHERN.EDU>]

Tim Folkerts wrote:

> I'm sure that most of us are aware that the lifetime of moving muons
> provied a direct confirmation of time dilation.  But today a students asked
> about length contraction, and I had to admit I couldn't think of any
> experiment that directly measured the effect.  Of course, it has to work
> for the rest of the theory to work, but is there a clear experiment that
> confirms it directly?
>
> Tim Folkerts
> Fort Hays State University

I recently had to answer the same question.  The only thing that came to
mind was the same muon decay results:  From the standpoint of the
experimenter, the speeding muons have an abnormally long half-life and a
large percentage of them survive the descent from the upper atmosphere
down to sea level (confirmation of time dilation), but from the
standpoint of the muons, their half-life is the expected value and it is
the distance down to earth which is length-contracted, giving precisely
the same percentage of muon survival from the two different viewpoints.
In that sense the same experiment confirms time dilation and length
contraction!

But I wonder if some sort of laser-ranging might not be useable to
directly measure length contraction of a macroscopic object, after
time-of-flight effects are subtracted out, of course.

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  | Ken CAVINESS           Physics at Southern Adventist University |
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