On Wednesday, December 11, 2024 at 4:07:33 AM UTC-7 Quentin Anciaux wrote:
Le mer. 11 déc. 2024, 12:05, Alan Grayson <[email protected]> a écrit : On Wednesday, December 11, 2024 at 2:56:30 AM UTC-7 Quentin Anciaux wrote: Le mer. 11 déc. 2024, 10:50, Alan Grayson <[email protected]> a écrit : On Wednesday, December 11, 2024 at 2:01:51 AM UTC-7 Alan Grayson wrote: On Wednesday, December 11, 2024 at 1:51:00 AM UTC-7 Quentin Anciaux wrote: Le mer. 11 déc. 2024, 09:46, Alan Grayson <[email protected]> a écrit : On Wednesday, December 11, 2024 at 1:39:54 AM UTC-7 Quentin Anciaux wrote: Le mer. 11 déc. 2024, 09:37, Alan Grayson <[email protected]> a écrit : On Wednesday, December 11, 2024 at 1:26:50 AM UTC-7 Quentin Anciaux wrote: In the thought experiment it always pass through the garage, just the following is frame dependent: the car is fully inside the garage and both doors are *simultaneously* closed, or part of the car is in the garage and doors are not simultaneously closed, in both view the car pass through the garage "undamaged", they just don't agree on the fact that the car was fully inside and both doors were simultaneously closed. Best to consider the garage like a covered bridge, open at both ends. IMO, there is only one reality. Therefore, however you want to define "fit", the car either fits or doesn't fit. There can be no ambiguity which is frame dependent. AG I give up... Maybe you should go to a monastery and meditate on this. I am not the kind of person who must be right, but on this issue I surely have made a provocative comment which must be taken seriously. AG You've just shown how stubborn and unwilling to understand you are. Believe what you want... Actually I'm not being stubborn. I just cannot imagine how seeing is not believing, in this case the car fitting or not fitting, each depending on different frame analyses. Maybe you're so committed to relativity that you can't imagine it being flawed. I admit; I don't know how relativity can satisfy what I see as basic logic and perception of the real world. AG If you study Brent's charts, you'll see that in the frame of the car, the car simply does NOT fit in the garage. It's not a question of some doors being closed, and others not. So, IMO, you must ask yourself this question; what will you actually see if the thought experiment can be performed in the physical world? AG Forget the doors, fit in, means the rear of the car is at the same location than the entrance of the garage (or past it) and simultaneously the front of the car is before or at the same location as the exit if the garage... it's clearly a problem of simultaneity and so dependent on the frame of reference. I don't disagree. But if you look at Brent's plots, he shows what I have been saying; namely, from the car's frame, the car doesn't fit; and from the garage's frame it does it (when car is modeled at v = .8c). So far, so good. BUT if you can imagine a physical experiment with the same parameters, you will presumably observe only ONE outcome. So what happened to the other outcome, apparently falsified? After all, it is impossible to observe both outcomes, since they contradict each other. THIS is the point I have been making all along. AG As an observer you can't be in both frame, so no, you can't see both, but two observers in two different frame will see things differently because there is no absolute frame of simultaneity. I'll have to think about your comment. OTOH, all inertial frames are equivalent. AG Le mer. 11 déc. 2024, 09:16, Alan Grayson <[email protected]> a écrit : On Wednesday, December 11, 2024 at 12:44:05 AM UTC-7 Alan Grayson wrote: On Tuesday, December 10, 2024 at 11:40:10 PM UTC-7 Alan Grayson wrote: On Tuesday, December 10, 2024 at 11:15:16 PM UTC-7 Brent Meeker wrote: Do I not only have provide a diagram I also have to explain it in detail just to end this silly thread?? *Yes you do. Providing plots without the numerical values in the LT, is useless. I can't tell if you're drawing plots to satisfy your biases, or if the numbers support the case you're making. Lesson learned; always do a real proof, which means supplying the arguments, or STFU. AG * *Brent; your numbers check out. The car fits with ease from the pov of the garage frame, but not from the pov of the car frame. But this bothers me since we know that all frames are equivalent in SR. How then can two, so-called equivalent frames, gives different results? Using the LT, measurements in different frames generally differ, but here something more fundamental seems to be happening; namely, that the car fits and doesn't fit, depending on the frame being analyzed. AG * *What I'm getting at is this; if one could do the experiment with a real car, it would either fit, or wouldn't fit. Do you agree? But in SR, the result is frame dependent. How would you reconcile this apparent problem or contradiction? AG * First note by comparing the two diagrams that the car is longer than the garage, 12' vs 10'. So the car doesn't fit at small relative speed. What does "fit" mean? It means that the event of the front of the car coinciding with the right-hand end of the garage is after or at the same time as the rear of the car coinciding with the left-had end of the garage. In both diagrams the car is moving to the right at 0.8c so \gamma=sqrt{1-0.8^2}=0.6. Consequently, in the car's reference frame, the garage is contracted to 6' length and when the rear of the car is just entering the garage, the front is *simultaneously*, in the car's reference frame, already 6' beyond the right-hand end of the garage. Then in the garage's reference frame the car's length is contracted to 0.6*12'=7.2' so at the moment the front of the car coincides with the right end of the garage, the rear of the car will simultaneously, in the garage reference system, be 2.8' inside the garage as shown below. Note that in the above diagram I have marked two simultaneous events with small \delta's. The diagram below is just the Lorentz transform of the one above. The two simultaneous \delta's are also in the diagram below. You can confirm they are the same events by referring to the time blips along the world lines, which are also just the Lorentz transforms of those above. But clearly the events marking the simultaneous locations of the rear and front of the car above are NOT simultaneous in the garage frame below. Conversely, the front and rear simultaneous locations of the car below are not simultaneous in the above diagram, as the reader is invited to confirm by plotting them. Simultaneity is frame dependent. Incidentally, when I was in graduate school this was still know as the "Tank Trap Paradox". The idea was that if one dug a tank trap shorter than the enemy tank, then the tank would just bridge the hole, UNLESS the tank were going very fast in which its contracted length would allow it to fall into the trap. This was being explained to me by Jurgen Ehlers, whom you may correctly infer from his name was a German professor recently hired at Univ Texas. I said, "What is it with you Germans, illustrating things with tank traps and cats in boxes with poison gas?" Jurgen who was too young to have fought in the war didn't realize I was pulling his leg and he was struck speechless. Brent -- 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]. 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