On Sep 29, 1:07 am, "Dirk Van de moortel" wrote in sci.physics.relativity:
> harald wrote:
> > Length contraction is often portrayed as nothing more than a
> > disagreement about the length of an object as measured in different
> > inertial coordinate systems. However, the word "contraction" implies a
> > CHANGE of length,
> Only to ether-addicts in disguise.
> To us, regular folks, it implies no such thing. It implies that if
> we first measure your thing when you are standing next to us,
> and then measure it when you are running away, it "becomes"
> shorter - as measured by us - not by yourself.
Some of your brothers Einsteinians are experts in trapping long objects inside short containers - they say without Divine Albert's Divine Special Relativity they would not be able to do so:
"Cependant, si une fusée de 100 m passait devant nous à une vitesse proche de celle de la lumière, elle pourrait sembler ne mesurer que 50 m, ou même moins. Bien sûr, la question qui vient tout de suite à l'esprit est: «Cette contraction n'est-elle qu'une illusion?» Il semble tout à fait incroyable que le simple mouvement puisse comprimer un objet aussi rigide qu'une fusée. Et pourtant, la contraction est réelle... mais SANS COMPRESSION physique de l'objet! Ainsi, une fusée de 100 m passant à toute vitesse dans un tunnel de 60 m pourrait être entièrement contenue dans ce tunnel pendant une fraction de seconde, durant laquelle il serait possible de fermer des portes aux deux bouts! La fusée est donc réellement plus courte. Pourtant, il n'y a PAS DE COMPRESSION matérielle ou physique de l'engin. Comment est-ce possible?"
"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."