According to Aleksandar Gjurchinovski, in
“Reflection of light from a uniformly moving mirror”

Am. J. Phys. 72 (10) Oct. 2004, 1316-1324 (from the abstract.):



" the contraction is a direct consequence of the first and second postulates
of special relativity, and is not a consequence of the relativistic
measurement of length."



His argument is based on light reflection from a mirror, which indeed
doesn't imply length measurement.

But he did not consider that it's just as real that there is no length
contraction, according to someone who is co-moving with the mirror...

Apparently after 1 year of debate, his paper got through. That's the mess
you get from a positivistic interpretation of the PoR. ;-)



Harald

Harry:
According to Aleksandar Gjurchinovski, in
“Reflection of light from a uniformly moving mirror”

Am. J. Phys. 72 (10) Oct. 2004, 1316-1324 (from the abstract.):



" the contraction is a direct consequence of the first and second
postulates of special relativity, and is not a consequence of the
relativistic measurement of length."

That's like saying the value of a one dollar bill is consequence
of the number of pennies you can get for it in exchange from the
cashier at the bank, and not a consequence of the way the treasury
department designed the monetary system defining the penny as 1/100th
of a dollar. The only way you could get the wrong number of pennies
is by being careless.

His argument is based on light reflection from a mirror, which indeed
doesn't imply length measurement.

Say what? Could you explain how it's possible, even in principle,
to know that a length is contracted until you define what length means
so that some basis for comparison exists?

"Bilge" wrote in message
...
Harry:
According to Aleksandar Gjurchinovski, in
"Reflection of light from a uniformly moving mirror"

Am. J. Phys. 72 (10) Oct. 2004, 1316-1324 (from the abstract.):



" the contraction is a direct consequence of the first and second
postulates of special relativity, and is not a consequence of the
relativistic measurement of length."

That's like saying the value of a one dollar bill is consequence
of the number of pennies you can get for it in exchange from the
cashier at the bank, and not a consequence of the way the treasury
department designed the monetary system defining the penny as 1/100th
of a dollar. The only way you could get the wrong number of pennies
is by being careless.

Yeah, ... or, more like saying that the number of pennies in one dollar
doesn't depend on the counting of the cashier but on the definition by the
monetary system.
But the point was, from a face-value (positivistic) interpretation of the
postulates he obtains that the "physical length of the moving mirror in the
direction of its motion is less than the physical length of the same mirror
in rest". He thus concludes that the contraction is not "apparent" (due to
the process of measuring length), but "real".
- As I indicated, IMO that can't be correct either - I just find this very
funny!

His argument is based on light reflection from a mirror, which indeed
doesn't imply length measurement.

Say what? Could you explain how it's possible, even in principle,
to know that a length is contracted until you define what length means
so that some basis for comparison exists?

In science everything is defined. According to him:
"In SRT the length of an object in a given inertial frame is defined as the
distance between any two simultaneous events that occur at the object's
ends."
He determined the length contraction from the calculated tilted angle of the
mirror surface that follows from the postulates, and not from a hypothetical
length measurement. For that he used Huygens, and in a follow-up paper also
Fermat. It reminded me of the discussion I had with Rafael VHG some time ago
in this newsgroup.

Harald