Edgar, I believe I may understand your point about a universal present, but it is something relativity handles, as far as I can see, without having to postulate anything new. Anything having the same (x, y, z, t) coordinates can interact, where t is coordinate time. It seems like you believe that because the twins are different ages (in different proper times), that they cannot interact. But they can, because each has traced exactly 10 light years through space-time (their coordinate times are the same).
So you might say everything with the same coordinate time, at the same place (x, y, z) the same, shares a present moment. But you cannot use this fact to extrapolate to spatially separated things sharing a present. For this, the definition of a present (what things exist having the same coordinate times) differs in different reference frames. Jason On Wed, Jan 1, 2014 at 3:01 PM, Jason Resch <jasonre...@gmail.com> wrote: > > > > On Wed, Jan 1, 2014 at 8:41 AM, Russell Standish <li...@hpcoders.com.au>wrote: > >> On Mon, Dec 30, 2013 at 01:20:35AM -0800, Edgar L. Owen wrote: >> > Jason, >> > >> > That's a totally off the wall answer. When the two shake hands it's not >> > just photons that are interacting, it's the electrons, protons and >> neutrons >> > of the matter of their hands which don't travel at the speed of light. >> > >> > Goodness gracious! >> > >> > Edgar >> > >> >> Jason is correct - electron-electron and electron-proton interactions >> are mediated by photons. Only nucleon-nucleon interactions are >> mediated by different stuff (gluons in that case), but for all >> practical purposes, the strong force is irrelevant to the phenomenon >> of handshaking. >> > > And if it were, say in some particle accelerator, the gluons also travel > at the speed of light and their present is spread across all proper times. > > >> >> Which gets us to the more important point. You idealise a handshake as >> instantaneous as a demonstration of your "present moment", but in fact >> those interactions Jason was alluding to are smeared out over a >> temporal duration of the order of a few picoseconds (a duration well >> measurable by current day technology - my laptop's CPU clock cycles on >> a sub-picosecond timescale, for example). >> > > You must have a VERY fast laptop! :-) > > Jason > > >> This doesn't matter much for human affairs, but becomes quite >> significant when extrapolating over cosmological scales. >> >> Cheers >> -- >> >> >> ---------------------------------------------------------------------------- >> Prof Russell Standish Phone 0425 253119 (mobile) >> Principal, High Performance Coders >> Visiting Professor of Mathematics hpco...@hpcoders.com.au >> University of New South Wales http://www.hpcoders.com.au >> >> ---------------------------------------------------------------------------- >> >> -- >> 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. >> > > -- 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.
