PAllen said:You are bundling things that need not be bundled. Relativity of simultaneity, to me, means NOTHING more than if two observers in relative motion synchronize clocks using the same procedure, each will think the other's clocks to be out of synch. It has nothing to do with a surface of simultaneity, nor with the FURTHER assumption that such surface has anything to do with what is fixed and certain. Further, you keep stating that believing 'past light cone is fixed' means only current event is real. I completely disagree with this coupling as well.
Nope, that is false logic. I can believe other people are known to have existed up to the surface of my past light cone instead of an SoS (which, in any case, has no preferred definition at all in GR, in general), and can predict their extremely high likelihood of existing beyond my past light cone. That is not solipsism unless you adopt the utterly absurd definition that anything other than BW (and not just BW - your particular flavor of it - see later) is solipsism. IMO, irrespective of BW (which I rather like, actually), the concept of 'now' at a distance has no objective meaning in SR or GR. In fact, I would argue that BW makes 'now' completely superfluous, since all foliations, and all history exists 'at once'.RUTA said:BW has to do with coexistence. If you believe other people coexist with you at any instant, then that constitutes a SoS and the argument for BW (coexistence of future, past and present) follows. If not, that's solipsism. It's that simple.
PAllen said:Nope, that is false logic. I can believe other people are known to have existed up to the surface of my past light cone instead of an SoS (which, in any case, has no preferred definition at all in GR, in general), and can predict their extremely high likelihood of existing beyond my past light cone. That is not solipsism unless you adopt the utterly absurd definition that anything other than BW (and not just BW - your particular flavor of it - see later) is solipsism. IMO, irrespective of BW (which I rather like, actually), the concept of 'now' at a distance has no objective meaning in SR or GR. In fact, I would argue that BW makes 'now' completely superfluous, since all foliations, and all history exists 'at once'.
Meaningless question because 'now' is only a convention in SR and undefinable in GR. The question itself is wrongheaded. IMO, SR partly, and GR fully, removed 'now' from having any possible objective meaning. This does not imply any unreality of the universe, only unreality of an obsolete Newtonian concept. The universe exists, "now" does not exist (in my current philosophical position).RUTA said:Does any thing else coexist with you right Now? If yes, then that collection of coexisting entities occupying that particular Now constitutes a SoS and the argument follows. If not, solipsism. You can claim you don't know, that's not an ontological claim, that's an epistemological claim. BW is an ontological claim.
PAllen said:Meaningless question because 'now' is only a convention in SR and undefinable in GR. The question itself is wrongheaded. IMO, SR partly, and GR fully, removed 'now' from having any possible objective meaning. This does not imply any unreality of the universe, only unreality of an obsolete Newtonian concept.
You are defining solipsism as anything you disagree with. I completely reject your definition. Most people have no relativistic understanding. It is a quite common position among relativists that 'now' has no meaning, and is purely a holdover from per-relativistic intuitions. I can't help it if you don't see that SR/GR make 'now' obsolete.RUTA said:Most people don't believe it's meaningless at all. What is my brother doing right Now in Ohio? Where is that probe in its orbit about Jupiter right Now? You want to find your friend in the store and text them, "Where are you?" Most people believe it's meaningful to assume those things all coexist with them Now. But, if you don't, that's solipsism. Again, it's very simple.