Re: Length Contraction

[Jack Uretsky <jlu@HEP.ANL.GOV>]

Hi all-
        Leigh's response emphasizes the point that <within the logical
framework of special relativity> length contraction implies time dilation
and vice-versa.  This equivalence is evident in the Lorentz
transformations of space and time.
        It is nevertheless a fair question, in my opinion, to ask for
independent experimental verification of both predictions.
        The only experimental verification of length contraction, of which
I'm aware, comes from the indirect measurements of the interaction regions
in collisions of heavy nuclei at Cern and elsewhere.  Those data can be
interpreted to show "flattening of the nuclei" along the collision axis.
                                                Regards,
                                                                Jack
On Thu, 14 Dec 2000, Leigh Palmer wrote:

> > I am wondering if someone could tell me what experimental evidence there has
> > been to confirm length contraction stated in Einstein's Special Theory of
> > Relativity. Thanking you in advance.
>
> Consider the atmospheric blanket of Earth as perceived in the frame
> of an extremely relativistic* secondary cosmic muon created in the
> upper stratosphere. With its 2.2 microsecond mean life the muon can
> "expect" to travel only about 660 meters, yet many such muons reach
> Earth's surface. The interpretation is that in the muon's frame of
> reference the atmosphere is only a few hundred meters thick, proof
> of the reality of length contraction. If the atmosphere were, say,
> 66 km thick, then the sky would have to be black with muons at the
> top of the atmosphere for any to survive to sea level. For one muon
> to make it without length contraction five trillion tons of muons
> would have to start out from that height.
>
> Leigh
>
> * velocity approximately equal to the velocity of light.

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