On Sun, Dec 22, 2024 at 7:49 AM Alan Grayson <[email protected]> wrote:
> > > On Saturday, December 21, 2024 at 5:00:13 AM UTC-7 Alan Grayson wrote: > > On Friday, December 20, 2024 at 3:35:05 AM UTC-7 Quentin Anciaux wrote: > > Why bother answering a troll ? He will never admit anything, will change > what he says if he's cornered. His sole purpose and pleasure is trolling. > You end a troll by ignoring it. Ignoramus as him and cosmin are better > dealt with plain silence, that's all these shitty human beings deserve. > > > http://insti.physics.sunysb.edu/~siegel/sr.html > > A famous "paradox" is trying to park a relativistic car in a garage: *From > the point of view of the car, the garage has "Lorentz contracted", and the > car will no longer fit. But from the point of view of the garage, the car > is now shorter, and so will fit even better. The resolution of the paradox > is that if the front end of the car stops simultaneously to the back end > from one "reference frame", that will not be true in the other.* If both > ends do not stop at the same time, the car changes length. (This has often > been observed nonrelativistically, for cars stopped by trees or other cars. > > Quentin; believe it or not, I'd like to be done with this problem. And > since IIRC you posted the above link, perhaps you will be so kind as to > explain it to me. If I read correctly, the author claims there appears to > be a contradiction concerning in which frame the car fits in the garage. It > appears that from the pov of the car, it can't fit in the garage due to > length contraction of the garage; whereas from the pov of the garage frame, > the car fits easily due to the car's length contraction. "*The* *resolution > of the paradox is that if the front end of the car stops simultaneously to > the back end from one "reference frame", that will not be true in the > other." * > > *I fail to understand the alleged resolution of the paradox. How does the > failure in simultaneity solve the paradox? Is the author claiming that > because there is a failure in simultaneity in the car frame, the car won't > stop in the car frame, even though it stops in the garage frame? Seriously; > please explain it if you can. TY, AG* > > > *Quentin; FYI the model of the paradox you posted is seriously flawed > because it assumes the car comes to an instantaneous rest when it fits in > the garage. Obviously, in this scenario, the car and garage would > instantaneously recapitulate the initial condition of the rest frame where > the car doesn't fit because it longer than the garage. Consequently, the > preferred scenario is to imagine the garage like a covered bridge with both > ends open, and use a velocity of the car exactly large enough so the car > perfectly fits in the garage as it passes through. Then, the front and back > end of the car are simultaneous at both openings. This is how Brent modeled > the problem, IIUC. And the alleged solution is that the simultaneity which > is achieved in the garage frame, fails in the car frame. So, the question I > pose for you and anyone here who is interested, is this; how, exactly, does > the disagreement of simultaneity solve the paradox (of the car fitting in > garage frame, but not in car frame when the car is moving at a sufficient > velocity)? TY, AG* > Maybe you are looking specifically for an answer from Quentin (I doubt he's interested in further discussion given his other comments), but I did already address this version on the other "ATTN Jesse" thread. This is a different version of the paradox that in effect is asking "OK, so if different frames disagree on whether the car fits, what happens if the car stops instantaneously when the front reaches the back of the garage? Wouldn't that let us decide which frame was right?" And the answer here is that "car stops instantaneously when..." is an ill-defined phrase due to relativity of simultaneity, and could describe either of two physically distinct scenarios where the back of the car stops (relative to the garage) at different events on its worldline. If event A is the front of the car reaching the back of the garage, then in one scenario the back of the car would stop at a point B that is simultaneous with A *in the car frame*, in which case the car would have the same rest length of 12 after stopping and would never have entered the garage. In the other scenario the back of the car would stop at a point C that is simultaneous with A *in the garage frame*, in which the car would be compressed in its new rest frame to a length 7.2, and the back end would already be inside the garage, meaning it fits. Again, these are distinct physical scenarios about when the back of the car stops relative to the garage, not just different frames' perspectives on the same physical scenario as in the version that Brent gave where the car remains inertial throughout and passes right through the garage like a covered bridge. BTW if I'm understanding you correctly it's not true that Brent's example involved a "car exactly large enough so the car perfectly fits in the garage as it passes through"--in his example the car's length didn't exactly match the garage's length in either of the two frames (though in his scenario it is possible to find a third frame, different from either the car rest frame or the garage rest frame, in which the car and garage are both Lorentz-contracted by different amounts such that their lengths in this frame are identical). Jesse > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion visit > https://groups.google.com/d/msgid/everything-list/aad57dfc-57a8-4d62-9b97-1e490d9d470en%40googlegroups.com > <https://groups.google.com/d/msgid/everything-list/aad57dfc-57a8-4d62-9b97-1e490d9d470en%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/everything-list/CAPCWU3KTb7n5z7-Gitu-A%3Dw2%2Br%3D%3D4FZVTYaMNSaYeHrd_PtT%3Dg%40mail.gmail.com.
