On Mon, Dec 9, 2024 at 8:28 PM Alan Grayson <[email protected]> wrote:
> > > On Monday, December 9, 2024 at 4:54:34 PM UTC-7 Brent Meeker wrote: > > > > > On 12/9/2024 3:24 PM, Alan Grayson wrote: > > On Monday, December 9, 2024 at 2:01:28 PM UTC-7 Brent Meeker wrote: > > > > > 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 > > The facts are events in spacetime. There's an event F at which the > front of the car is even with the exit of the garage and there's an > event R at which the rear of the car is even with the entrance to the > garage. If R is before F we say the car fitted in the garage. If R is > after F we say the car did not fit. But if F and R are spacelike, then > there is no fact of the matter about their time order. The time order > will depend on the state of motion. > > Brent > > > Since the car's length can be assumed to be arbitrarily small from the > > pov of the garage, why worry about fitting the car in garage perfectly, > and then appealing to difference in spontaneity to prove no direct > contradiction between the frames? It seems like a foolish effort to > > avoid a contradition, when one clearly exists. AG > > > What's the contradiction? > > > *ISTM that the car can, or cannot fit in garage given the initial > condition that in the rest frame, the car is longer than the garage; in > other words there is an objective reality, but the frames differ on whether > the car fits or not.* > Can you define what "fits in the garage" would mean in objective terms, i.e. a definition that does not depend on simultaneity or choice of frame? If you can't even define that phrase in any objective terms, why do you believe there is any objective reality here? Is it just some kind of strong intuitive hunch that there "should" be some kind of objective reality attached to such a notion? * If one avoids the issue of simultaneity, by not requiring the car to > perfectly fit in the garage, we get opposite conclusions from the frames. > AG* > The paradox does not depend on the assumption that the car is the same length as the garage in either the car frame or the garage frame (or that they have the same rest length), if that's what you mean by "perfectly fit in the garage". Even if the car's rest length is much shorter than the garage's rest length, so it fits easily in the garage frame, you could always pick a sufficiently large relative velocity such that the car would be longer than the garage in the car's rest frame, and thus it would not fit in that frame, so the paradox remains. Not sure what "opposite conclusions from the frames" could mean if you don't have a specific way to define "fits in the garage" in a way that doesn't depend on picking some frame or another. 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/CAPCWU3L5Tb5ZOEy_8E-cJfvowFcvcXP%2Bwx4gOoQ7etQaNkbWaw%40mail.gmail.com.
