On Monday, December 9, 2024 at 9:29:34 AM UTC-7 Quentin Anciaux wrote:
Le lun. 9 déc. 2024, 17:20, Alan Grayson <[email protected]> a écrit : On Monday, December 9, 2024 at 8:58:05 AM UTC-7 John Clark wrote: On Mon, Dec 9, 2024 at 9:28 AM Alan Grayson <[email protected]> wrote: On Monday, December 9, 2024 at 7:17:07 AM UTC-7 John Clark wrote: *For heaven sake! Nobody is denying that two observers in two different frames of reference can and will observe different things and thus disagree if the car was ever entirely in the garage or not; just as they disagree about how long a meter stick is and how fast a clock ticks. But that's not a logical paradox, that's just strange. And objective reality does exist in relativity because some things DO remain constant in ANY frame of reference, such as the speed of light and the distance through spacetime of ANY two events. * *An event, such as the closing of both the front and back doors of the garage, is a specific point in space and time, t**he contraction of length and the stretching of time are not independent properties; they always change in such a way that the garage man in the car driver agree that the distance through spacetime between the front of the car entering the front of the garage in the back of the car exiting the back of the garage is exactly the same. But because they disagreed about length and time (but not when both are considered together) they will sometimes disagree if there was ever a time when both doors were closed AND the front and the back of the car were both in the garage. * *John K Clark * 1 *> If that's your present position,* *I**t has always been my position** that there is nothing paradoxical about two observers disagreeing if a car had fit in the garage for an instant or not, and it has always been my position that there will NEVER be an occasion where one observer sees the car make a car shaped hole in the back door of the garage but the other observer sees no such damage because * *THAT** would have been a paradox, it would've been a logical contradiction which is what you need to produce a paradox. * *> why, when I first stated that the frames differed on whether the car will fit in the garage, did you claim the alleged flaw I described, would, if true, undermine 120 years of professional thinking about relativity?* *Because you kept making a big deal about it and because you kept calling it a "paradox" which it is not. It's just odd. * *> now you've made a 180 degree turn on its implication* *Actually I've made a 360 degree turn on its implication. * *If γ = 1 / √(1 - v²/c²) then Length Contraction reduces the length by 1/γ, and Time Dilation increases the time interval by γ, so they disagree about length and they disagree about time but they agree when space and time are both considered together in spacetime.* *John K Clark See what's on my new list at Extropolis <https://groups.google.com/g/extropolis>* Nothing odd about dilation and contraction when you know its cause. But what is odd is the fact that each frame sees the result differently -- that the car fits in one frame, but not in the other -- and you see nothing odd about that, that there's no objective reality despite the symmetry. AG tst You discovered that in relativity there is no absolute frame of reference and so no objective simultaneity which in the end the "paradox" reduce to it, there is no objective truth about simultaneity of two spacetime events. No. I knew that 50+ years ago. But I thought the LT gave an objective fact about how events transform between frames. Now I doubt that, and what the LT gives. AG -- 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/6a595702-44b4-45e3-a33f-c4ecc6a36b1bn%40googlegroups.com.
