On Monday, December 9, 2024 at 10:55:39 PM UTC-7 Alan Grayson wrote:
On Monday, December 9, 2024 at 10:31:51 PM UTC-7 Brent Meeker wrote: On 12/9/2024 5:28 PM, Alan Grayson 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. 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* *If you define "fit in" it requires using the concept of simultaneity. Brent* *I have been considering this possibility. If true, does it mean a car fitting in a garage can never be compared to how it appears in the garage frame, and that there's no objective reality? AG* *I forget; what problem is ostensibly solved in the car's perfect fit scenario in the garage, by the fact that simultaneous events for the front and rear end of the car, are not simultaneous in the frame of the garage. TY, 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/9934420b-4cc2-40a1-b9c1-b569d8fd58a5n%40googlegroups.com.
