http://math.ucr.edu/home/baez/physics/

http://math.ucr.edu/home/baez/physics/Relativity/SR/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. Now someone takes the pole and tries to run (at nearly the speed of light) through the barn with the pole horizontal. Special Relativity (SR) says that a moving object is contracted in the direction of motion: this is called the Lorentz Contraction. So, if the pole is set in motion lengthwise, then it will contract in the reference frame of a stationary observer.....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. The runner emerges from the far door unscathed.....If the doors are kept shut the rod will obviously smash into the barn door at one end. If the door withstands this the leading end of the rod will come to rest in the frame of reference of the stationary observer. There can be no such thing as a rigid rod in relativity so the trailing end will not stop immediately and the rod will be compressed beyond the amount it was Lorentz contracted. If it does not explode under the strain and it is sufficiently elastic it will come to rest and start to spring back to its natural shape but since it is too big for the barn the other end is now going to crash into the back door and the rod will be trapped in a compressed state inside the barn."

The premise on which this conclusion is based is Einstein's 1905 light postulate so if rationality in science had not been destroyed, Einsteinians would have presented the above deduction as REDUCTIO AD ABSURDUM and, accordingly, would have rejected the light postulate as false. In the era of Postscientism the compressed 80m long pole inside the 40m long barn can only be a glorious manifestation of the validity of Divine Albert's Divine Theory.

Pentcho Valev
pvalev@yahoo.com

Pancho,

it is a fact that the moving objects actully contract, physically contract. This is due to the interatomic forces that hold it together. The EM field. This is simple Maxwell equations that say it is so. However, you cannot stop the pole in the barn, that would cause an expansion, deceleration etc.. So, if you are satisfied with a moving pole, then you can have it enclosed in the bar for a short time. The SRT works, experiments confirm it, so you may as well accept it even if you do not understand it.

Regards, Graviton

>>So, if you are satisfied with a moving pole, then you can have it enclosed in the bar[n] for a short time.

you are not taking into account the nonsense of relativity-- from the point of view of a person stationary with respect to the barn, the pole has shrunk; from the pole's frame - the barn has shrunk. So one person says yes pole is enclosed in barn, the other says no it isn't; so which person is correct (?); Einstein relativity answers - all absurdities, all contradictions and all nonsense is allowed.

Pentcho Valev wrote:
>http://math.ucr.edu/home/baez/physics/
>
>http://math.ucr.edu/home/baez/physics/Relativity/SR/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. Now someone takes the pole and tries to run (at nearly the
> speed of light) through the barn with the pole horizontal. Special
> Relativity (SR) says that a moving object is contracted in the
> direction of motion: this is called the Lorentz Contraction. So, if
> the pole is set in motion lengthwise, then it will contract in the
> reference frame of a stationary observer.....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. The
> runner emerges from the far door unscathed.....If the doors are kept
> shut the rod will obviously smash into the barn door at one end. If
> the door withstands this the leading end of the rod will come to rest
> in the frame of reference of the stationary observer. There can be no
> such thing as a rigid rod in relativity so the trailing end will not
> stop immediately and the rod will be compressed beyond the amount it
> was Lorentz contracted. If it does not explode under the strain and
> it is sufficiently elastic it will come to rest and start to spring
> back to its natural shape but since it is too big for the barn the
> other end is now going to crash into the back door and the rod will be
> trapped in a compressed state inside the barn."
>
> The premise on which this conclusion is based is Einstein's 1905 light
> postulate so if rationality in science had not been destroyed,
> Einsteinians would have presented the above deduction as REDUCTIO AD
> ABSURDUM and, accordingly, would have rejected the light postulate as
> false. In the era of Postscientism the compressed 80m long pole inside
> the 40m long barn can only be a glorious manifestation of the validity
> of Divine Albert's Divine Theory.

http://hyperphysics.phy-astr.gsu.edu/Hbase/Relativ/bugrivet.html
"The bug-rivet paradox is a variation on the twin paradox and is similar to the pole-barn paradox.....The end of the rivet hits the bottom of the hole before the head of the rivet hits the wall. So it looks like the bug is squashed.....All this is nonsense from the bug's point of view. The rivet head hits the wall when the rivet end is just 0.35 cm down in the hole! The rivet doesn't get close to the bug....The paradox is not resolved."

REDUCTIO AD ABSURDUM par excellence: the bug is both dead and alive. Einstein's 1905 light postulate from which this conclusion is deduced should be rejected as false.

http://www.bartleby.com/173/23.html
Albert Einstein: "Let us consider a space-time domain in which no gravitational fields exists relative to a reference-body K whose state of motion has been suitably chosen. K is then a Galileian reference-body as regards the domain considered, and the results of the special theory of relativity hold relative to K. Let us suppose the same domain referred to a second body of reference K', which is rotating uniformly with respect to K. In order to fix our ideas, we shall imagine K' to be in the form of a plane circular disc, which rotates uniformly in its own plane about its centre. An observer who is sitting eccentrically on the disc K' is sensible of a force which acts outwards in a radial direction, and which would be interpreted as an effect of inertia (centrifugal force) by an observer who was at rest with respect to the original reference-body K......To start with, he places one of two identically constructed clocks at the centre of the circular disc, and the other on the edge of the disc, so that they are at rest relative to it. We now ask ourselves whether both clocks go at the same rate from the standpoint of the non-rotating Galileian reference-body K. As judged from this body, the clock at the centre of the disc has no velocity, whereas the clock at the edge of the disc is in motion relative to K in consequence of the rotation. According to a result obtained in Section XII, it follows that the latter clock goes at a rate permanently slower than that of the clock at the centre of the circular disc, i.e. as observed from K."

REDUCTIO AD ABSURDUM par excellence. If Einstein had been honest, his text would be: "According to a result obtained in Section XII, it follows that either clock goes at a rate permanently slower than the other clock". The only camouflage Einsteinians use in this case is based on the fact that the clock placed "on the edge of the disc" experiences some "gravitational field", a fact which, according to Einsteiniana's perverse logic, implies that the reciprocal time dilation following from Einstein's 1905 false light postulate (either clock runs slower than the other) should somehow become non-reciprocal (the clock experiencing no gravitational field should become faster than the clock experiencing a gravitational field). However clever Einsteinians know that, by increasing the diameter of the disc and keeping the linear speed of the periphery constant, one can reduce the gravitational field to zero. Then another slight modification of the thought experiment (the non-rotating clock should be placed in the vicinity of the rotating periphery) makes the absurdity of the "reciprocal" conclusion obvious. Einstein's 1905 light postulate, the source of all such absurdities, should be rejected as false.

Pentcho Valev
pvalev@yahoo.com

On Jun 13, 5:11 pm, PD wrote in sci.physics.relativity:
> On Jun 13, 12:48 am, Pentcho Valev wrote:
> >http://hyperphysics.phy-astr.gsu.edu/Hbase/Relativ/bugrivet.html
> > "The bug-rivet paradox is a variation on the twin paradox and is
> > similar to the pole-barn paradox.....The end of the rivet hits the
> > bottom of the hole before the head of the rivet hits the wall. So it
> > looks like the bug is squashed.....All this is nonsense from the bug's
> > point of view. The rivet head hits the wall when the rivet end is just
> > 0.35 cm down in the hole! The rivet doesn't get close to the
> > bug....The paradox is not resolved."
>
> > REDUCTIO AD ABSURDUM par excellence: the bug is both dead and alive.
> > Einstein's 1905 light postulate from which this conclusion is deduced
> > should be rejected as false.
>
> Poor web page by someone who does not understand the physics. The bug
> is dead in both frames. There is no paradox.
>
> >http://www.bartleby.com/173/23.html
> > Albert Einstein: "Let us consider a space-time domain in which no
> > gravitational fields exists relative to a reference-body K whose state
> > of motion has been suitably chosen. K is then a Galileian reference-
> > body as regards the domain considered, and the results of the special
> > theory of relativity hold relative to K. Let us suppose the same
> > domain referred to a second body of reference K', which is rotating
> > uniformly with respect to K. In order to fix our ideas, we shall
> > imagine K' to be in the form of a plane circular disc, which rotates
> > uniformly in its own plane about its centre. An observer who is
> > sitting eccentrically on the disc K' is sensible of a force which acts
> > outwards in a radial direction, and which would be interpreted as an
> > effect of inertia (centrifugal force) by an observer who was at rest
> > with respect to the original reference-body K......To start with, he
> > places one of two identically constructed clocks at the centre of the
> > circular disc, and the other on the edge of the disc, so that they are
> > at rest relative to it. We now ask ourselves whether both clocks go at
> > the same rate from the standpoint of the non-rotating Galileian
> > reference-body K. As judged from this body, the clock at the centre of
> > the disc has no velocity, whereas the clock at the edge of the disc is
> > in motion relative to K in consequence of the rotation. According to a
> > result obtained in Section XII, it follows that the latter clock goes
> > at a rate permanently slower than that of the clock at the centre of
> > the circular disc, i.e. as observed from K."
>
> > REDUCTIO AD ABSURDUM par excellence. If Einstein had been honest,
>
> Sorry, no, you cannot attain reductio ad absurdum by substituting what
> was really said with something you say instead, which then leads to a
> contradiction. In the way that it was actually said, there is no
> contradiction.

Let us sing Clever Draper, let us sing:

http://www.youtube.com/watch?v=5PkLLXhONvQ

http://www.haverford.edu/physics/songs/divineEinstein.pdf

http://www.youtube.com/watch?v=7Z7GtgfTZ6w&feature=related&pos=2
"If you see someone approach the speed of light,
his time slows down, it's true,
but if this guy looks back at you he might
say, the slower one is you
Even though you're standing relatively still,
you'll observe this change but will
yet appear to change as well,
and the truth is that both measurement are true,
cause from this guy's point of view
the moving one is you
And the reason is the speed of light, which is
the mother of all speeds,
and some pure deduction simply based on this
is all the open minded needs
To conclude that you are never standing still,
compared to someone else you will
still be moving anyway,
and the truth is that all measurements are true
cause from some guy's point of view
the moving one is you
However, one thing's always the same,
in every single reference frame
the speed of light remains
a constant to us all, yeah!
The truth is that all measurements are true,
cause from some guy's point of view,
the moving one is you"

Pentcho Valev
pvalev@yahoo.com

Anonymous,

I think that you have to be careful how you measure lengths. Since you are now in the system where the pole is in rest, then your meters are shorter. So, barn in the rest is now longer relative to you. So when the barn moves relative to you it will shrink to the correct distance and the pole will fit.

Stupidon,

Don't teach Anonymous about SR.
He does not have more neurons than you.
In you answer you missed the main point: it is all about simultaneity.

Anonymous.

I did not want to strain your neurons with simultaneity, just the relative length measurements should be enough.

Regards, Graviton

You should not fear any strain with simultaneity questions.
You should try youself to visulaize any such questions in the Minkowsky diagram.
This method anneals any strain and illustrate all these questions are really trivial.
The only strain that will remain forever is:

Why are people so stupid?
Why do they not understand a simple 2-dimensional (x,t)=>(x',t') transformation?
An why do they not understand how kind Einstein was to explain it with down-to-earth arguments?
Why are so many people still entangled in pre-Einstein physics?

This is a real strain for me: stupidity sucks.

Stupidity does suck. The two dimensional transform for a transverse pulse of light from a point in one frame becomes a line in the other oppositely going frame. You are too stupid to realize this fact.

There is nothing more stupid than a claim that its author cannot explain.
Here is an example:

"The two dimensional transform for a transverse pulse of light from a point in one frame becomes a line in the other oppositely going frame."

The author can for sure give no meaning to the words "transverse pulse of light".
He can even not develop his point about a point becoming a line.
He is even unable to clarify the context of his statement.
He can even not explain why he pops up with such a sentense.
He could just have said: "the pope disappeared in his bicycle".

Yet Another Anonymous said: "There is nothing more stupid than a claim that its author cannot explain.
Here is an example:

"The two dimensional transform for a transverse pulse of light from a point in one frame becomes a line in the other oppositely going frame."

The author can for sure give no meaning to the words "transverse pulse of light".
He can even not develop his point about a point becoming a line.
He is even unable to clarify the context of his statement.
He can even not explain why he pops up with such a sentense.
He could just have said: "the pope disappeared in his bicycle".

Another Anonymous says: I can too: A "transverse pulse of light" Is simply a pulsed ray of light transverse to the motion between frames. You are too brain dead to understand.

You are, unbeknown to yourself, the Pope's only conceived daughter.