On Saturday, September 20, 2025 at 7:42:58 AM UTC-6 Alan Grayson wrote:
On Saturday, September 20, 2025 at 1:25:44 AM UTC-6 Brent Meeker wrote: On 9/18/2025 11:54 PM, Alan Grayson wrote: On Thursday, September 18, 2025 at 11:31:57 PM UTC-6 Brent Meeker wrote: On 9/18/2025 8:27 AM, Alan Grayson wrote: You keep saying that as if it's a mantra. What's a change in direction if it not deviation from a straight path? *In your neutron star example of turnaround, the motion starts as a straight line but continues turning for awhile. More important is your claim the GR cannot be used to solve the TP, yet here you are using it. AG * *TP is not a problem. So what do you mean by "solve"it; make AG stop posting about it? * *If it's not a problem why did E write about it? It becomes a "problem" if you make an error when positing it. So "solving it" makes sense. AG* * I already wrote a post explaining how the examples I've created each eliminate one of the causes that students often mistakenly think of as causing the aging difference. * *Brent* *If you have two different paths in spacetime with the same starting and end events, each path length is invariant under the LT, but as far as I know there's no way to compare the paths to determine their relative lengths. * Of course there is. You integrate the proper time along each path. The resulting durations are invariants; they are what an ideal clock measures along the path. The 3-lengths are not invariants and their length depends on how fast you traverse them. We've discussed this for months and you *just now* realize you need to measure duration along the paths?? *Speculating with an "expert" like you is depressing since you take every opportunity to put me down. I figured that if path length is invariant under the LT, and it depends on space and time, either can change, not that one is invariant and the other not. AG * That's what we've done in the SR case where it's easy and you don't have to integrate along them Brent *Again, the expert speaks with forked tongue; IOW paradoxically; not intelligible for us ordinary mortals. I figure that proper time along any path is a fixed quantity, yet now you say 3-lengths are NOT invariant. But if proper time is invariant, and 3-lengths not, since total S length is invariant, how can proper time be invariant? AG* *If this is true, even when it appears that one is shorter than another, there doesn't seem to be a way to make the comparison to determine which has shorter proper time. Is this correct, and if not, why? 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/37616016-bb12-44b5-9a73-a8fcb2fe57d6n%40googlegroups.com.
