On Friday, May 30, 2025 at 3:34:21 PM UTC-6 Brent Meeker wrote:
On 5/30/2025 3:03 AM, Alan Grayson wrote: On Friday, May 30, 2025 at 3:13:02 AM UTC-6 Brent Meeker wrote: On 5/29/2025 11:18 PM, Alan Grayson wrote: On Thursday, May 29, 2025 at 9:16:02 PM UTC-6 Brent Meeker wrote: On 5/29/2025 5:12 PM, Alan Grayson wrote: On Thursday, May 29, 2025 at 3:34:34 PM UTC-6 Brent Meeker wrote: On 5/29/2025 6:22 AM, John Clark wrote: I know that your next question will be why is nature inherently lazy? My short answer is I don't know. My slightly longer answer is I suspect that question simply has no answer because it is a brute fact. After all, an iterated sequence of "why" questions either goes on forever or terminates with a brute fact. You may not like either eventuality but one of them must be true. One thing that leads to confusion (and endless questions from AG) in popular discourse is that Lagrangians and least-action and differential equations and Hamiltonians, etc, are *maps* not the territory and, depending on which map you're using, you find the boundary "brute fact" to have different expression. Brent One brute fact worth mentioning, is that unless and until we understand why gravity chooses the extremal path, we can't say we understand it. Another point is about the clock. Test particles have no clocks, so how do they "know", as they traverse an extremal path, that it is in fact extremal? AG You completely missed the point that the exact same problems solved by finding the extremal path can also be solved by half a dozen other methods and they are all mathematically equivalent. So it make no sense to ask how Nature knows to use this or that method. Brent Fine. Then accept the fact that you don't really understand gravity, and with that attitude you never will. AG Define "really understand" and give an example of something you really understand. Brent For example, generally what operators are, and specifically that Hermitian operators have real eigenvalues. AG That's just mathematics. You asked me what I really understand, and I told you. You can't claim that we understand mathematics because we invented it, because the same can be said of physics. I understand some of the conservation laws, such as conservation of charge and energy. What I can say is that you don't understand gravity, and that won't occur until there is a deeper theory which explains why motion in a gravity field obeys extremal principles. AG Mathematics can be understood because we invent it. We understand the theory of general relativity but it's a map of gravity, not gravity itself. To understand something in physics generally means explaining it in terms of something more fundamental. So string theory seemed to explain some things about gravity, e.g. why the graviton was spin 2 and why gravity was so weak. But it has stalled in other respects. 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]. To view this discussion visit https://groups.google.com/d/msgid/everything-list/b226f061-cd99-4fbb-9db8-dc7e4ead6b3fn%40googlegroups.com.
