On Mon, Dec 24, 2018 at 12:06 PM Jason Resch <[email protected]> wrote:
> On Sun, Dec 23, 2018 at 7:51 PM Brent Meeker <[email protected]> wrote: > >> >> That's what I thought you wanted to conclude. But it doesn't follow. >> The specious present is just a mathematical construct and has no physical >> significance. It says no more than that one can make a 4D map. >> > > So do you believe that presentism is compatible under relativity? If one > puts two synchronized clocks (one at the front, and one at the read) of a > rocket, and then the rocket accelerates, the rocket attains a tilted > direction in space time, and while the rocket remains at a positive > velocity, the rear-ward clock will be "ahead in time" of the forward > clock. The rocket is reaching through the dimension of time which explains > the discrepancy of the clocks. When the rocket comes to rest, the rocket > will have "0" reach through the proper time dimension, and the clocks will > again appear synchronized. If something can have an extent through the > proper time dimension, how can this be compatible with presentism? > Your example does not require any such conclusion. If you have a clock at the front of an accelerating rocket, and one at the rear, the rear of the rocket has to accelerate at a slightly greater rate or else the rocket will fall apart. In the greater acceleration field, the rear clock will run slower than the clock at the nose. When the rocket comes to rest again, the two clocks will have travelled different non-geodesic paths, so they will no longer be synchronized the rear clock will show a smaller elapsed proper time than the forward clock. What is it, exactly, that you want to conclude from this? Time is what is measured on a clock, and clocks at different relative velocities, or different acceleration fields, will record different times. So the only reasonably objective "present" is that read on your local clock -- other clocks may well record different "presents". Bruce -- 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 post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
