Quantitative Prediction of a Measurable Quantity
On Aug 14, 2:11*pm, Y wrote:
Oh look. If an 80m pole dosn't fit in a barn, you will need to bend it
or something.
Whoever suggests that the doors can close in instant keeping the pole
neatly inside for that instant is crackers. If the Maths allow for it,
the maths are wrong, simple as that.
Actually, it's not the math that allows it, it's the laws of physics!
Only thing required to do, is keep testing the math in a friendly way
to ensure that this falsehood doesn't crop up. If it can be
demonstrated that it does, then the math is certainly questionable.
On Aug 14, 8:01 am, PD wrote:
On Aug 13, 4:12 pm, Pentcho Valev wrote:
On Aug 13, 9:21 pm, PD wrote:
On Aug 13, 1:57 pm, Pentcho Valev wrote:
On Aug 13, 6:42 pm, PD wrote:
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."
Bravo Clever Draper! Bulgarians are by no means addled - rather, they
adore you and your answers. Just a small elaboration: "the
quantitative prediction for the length of the pole in the barn frame
is not 80m but 39m" but then, when the pole is safely trapped inside
the barn, it will try to restore its proper length (which is 80m).
Why would it do that? The doors NEVER touch the ends of the pole.
If you have a fly that flies into a barn and you shut the doors of the
barn, the fly continues to fly around inside the barn, and when you
open the doors of the barn, the fly flies out.
Why are you assuming the pole is brought to rest inside the barn? You
perhaps misunderstand the barn and pole puzzle as it is commonly
taught.
The pole enters the barn.
The doors are briefly shut, while the pole is *still* moving at
constant velocity.
The doors never touch the ends of the pole.
Before the pole reaches the far door, the doors are opened back up.
The pole continues to fly out, never having changed speed.
You mean ALL THIS TIME you've been flummoxed by the barn and pole
paradox BECAUSE YOU CAN'T READ???
But
since the doors of the barn don't break, the pole will be able to
restore only 1 meter so when Clever Draper goes and measures the
length of the trapped pole, Clever Draper clearly sees a 40m long
pole, perhaps a few centimetres longer if the doors are slightly
deformed. Is this realistic, Clever Draper? A 40m long pole and that's
it?
Clever Draper, Cleverest Draper, why these zombie tricks again? Look
at my initial question and you will see the phrase:
"....provided your brothers have forgotten to reopen the doors of the
barn "pretty quickly"...."
Then your question is, is it a quantitative prediction that an 80m
pole will be trapped *intact* in a 40m barn if you decide to keep the
barn doors closed? The answer to that is: no, relativity makes no such
prediction.
If you close the doors and strike one end of a very rapidly moving
pole with the barn door, then all sorts of other physics gets
involved.
But then Clever Draper goes to the place (he is curious this Clever
Draper) and measures the length of what was once a 80m long pole but
is now something trapped inside the 40m long barn. What is the maximal
length of this something trapped inside the 40m long barn? 40m
perhaps? Special relativity does not predict even this?
No, of course not. Special relativity doesn't have anything to do with
the length of a pole after it's been hit with a barn door. Why would
you think it does?
Any theory is closely related to its implications, even when some of
them are absurd. Special relativity predicts that a 80m long object
can be trapped inside a 40m long container.
No, it doesn't say that, if by "trapped" you mean "brought to a stop".
It says no such thing.
Then the description of
the state of the trapped object is special relativity's implication.
Some time ago we discussed the same problem and then you said, if I am
not mistaken, that the density of the trapped object can increase
twice. That was special relativity's implication, although idiotic.
No, that is not special relativity's implication. That is the
implication of the rest of the physics that gets involved when you
have a door smacking into a pole. And no, it is not idiotic.
Pentcho Valev
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