On Aug 13, 8:25*am, Pentcho Valev wrote:
On Aug 13, 2:30*pm, PD wrote in
sci.physics.relativity:

I think you don't know what a physical theory is.
Can you please provide a quantitative prediction of a measurable
quantity?
That's what a physical theory does.

PD

Clever Draper, I have aleady asked you and you did reply I must admit
but I cannot remember your answer so again: What is the quantitative
prediction, Clever Draper, for the length of a 80m long pole safely
trapped inside a 40m long barn, provided your brothers have forgotten
to reopen the doors of the barn "pretty quickly" and the doors don't
break:

Well, of course the quantitative prediction depends on the relative
speed between the pole and the barn, but there certainly is a value of
the relative speed for which the quantitative prediction for the
length of the pole in the barn frame is not 80m but 39m. (The "80m"
you referred to in your question above is an adjective that presumably
applies in the rest frame of the pole, but does not apply in any other
frame.) This yields the qualitative prediction that the doors can be
closed briefly without touching either end of the pole.

Now, no one has done this exact experiment with a barn and a pole,
though there is a clearly a quantitative prediction. Fortunately, the
theory makes a number of other quantitative predictions which HAVE
been tested -- and confirmed -- in experiment.

The role of the barn-and-pole puzzle is then left, not as an
experimental prediction, but as a teaching exercise -- which
apparently still leaves some Bulgarians addled.


http://www.math.ucr.edu/home/baez/ph...barn_pole.html
"These are the props. You own a barn, 40m long, with automatic doors
at either end, that can be opened and closed simultaneously by a
switch. You also have a pole, 80m long, which of course won't fit in
the barn....So, as the pole passes through the barn, there is an
instant when it is completely within the barn. At that instant, you
close both doors simultaneously, with your switch. Of course, you open
them again pretty quickly, but at least momentarily you had the
contracted pole shut up in your barn."

Pentcho Valev