Everyone else has made excellent, well laid-out arguments against your position Edgar, but I will throw in another perspective. You ask whether two observers 'share the same common present moment'. However you don't define what that means exactly. If I imagine your scenario of two observers who aren't me then of course they seem to share the same moment, regardless of how far apart they are. To say they "don't share the same moment" would be like saying that one exists and the other doesn't at some point in time, right? But this is really begging the question about what a "point in time" is. You seem to be relying on an intuitive sense of time that is not bound to anything measurable (the hidden point of my tongue-in-cheek 'U-time'). How need to define what you mean by "sharing the same moment" and you need to show how it is to be measured. I submit that the only method of making such a determination is by means of something that measures clock time. For example, a clock! And you already agree that clocks will show that the observers don't precisely agree about the simultaneity of events.
In fact, to make the whole situation clearer, it is better not to use observers or people as the objects said to share the same common present because observers persist in time and this makes things less clear. Instead, you should ask the same question about a momentary event like a pulse of light from a diode. Do the diodes themselves share the "same present moment"? Yes, whatever that means! Do the flashes occur simultaneously? Well you know the answer depends on the inertial frame of reference. Substituting a mental event (the thought "I am here now") for the light flash, we can see that two thinkers cannot have that thought at an objectively identical moment. All events can be timed using clocks, which after all cold be anything that has a regular cycle. There is nothing in space-time, including mental events, that is not an event that can be timed in this manner. What is confusing you is merely the persistence of the observer and the impossibility of imagining that both observers don't exist at any point in time you can imagine. But *what* observer? The observer is constantly changing, and the only way to see if they share the same moment is to time the changes in each using clock time. P-time is an ad hoc postulate to save your intuition of an all-embracing moment. It fails when you try to operationalize it. Please, rather than reiterate your intuition, refute this point. On Saturday, December 28, 2013 10:57:18 AM UTC+11, Edgar L. Owen wrote: > > All, > > I haven't made any progress getting the idea of a common universal present > moment across so here's another approach with a thought experiment.... > > To start consider two observers standing next to each other. Do they share > the same common present moment? Yes, of course. Any disagreement? > > Now consider those two observers, one in New York, one in San Francisco. > Do they share the same common present moment? In other words is the one in > San Fran doing something (doesn't matter what) at the exact same time the > one in New is doing something? Yes, of course they do share the same > present moment. Any disagreement? > > Now consider an observer on earth and an observer in some far away galaxy. > But with the condition that they share the exact same relativistic frame in > the sense that there is zero relative motion and the gravities of their > planets are exactly the same so that clock time is passing at the exact > same rate on both their clocks. > > Now are these two observers sharing the exact same present moment as well? > Note that we just extended the exact same relativistic circumstances of the > previous two examples so there can be no relativistic considerations. Do > these two observers also share the exact same present moment as well? Yes, > of course they do. Not only do they share the exact same present moment but > they also share the exact same clock time t value. Any disagreement? > > OK, if you agree then you have to take a partial step towards accepting my > thesis of a common universal present moment. You now must agree that there > is at least a common universal present moment across the universe for all > observers in the same relativistic frame. > > Agreed? > > Edgar > -- 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 everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
