- #71
PeterDonis
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Lynch101 said:this part of the premise derives from the fact that the mathematics do not privilege any events on the world lines of objects, over any other events.
The statement you make here is irrelevant to the second premise described in my article, because it is about the wrong set of events. The statement you make here is about the set of events on some observer's worldline. But a "3D world", which is what the second premise referred to in my article is about, is a spacelike 3-surface, not a timelike worldline. So it is simply a non sequitur to go from your statement here to any statement about 3D worlds, including the second premise I talk about in my article.
Lynch101 said:If it cannot have a causal influence on other events, then it cannot happen and will never be observed.
This is irrelevant, since nowhere has anyone claimed that there is any event in 4D spacetime that cannot have a causal influence on any other events. Such a statement is obviously false for Minkowski spacetime, and indeed for any globally hyperbolic spacetime, which includes any spacetime considered to be physically relevant in General Relativity. So you appear to be attacking a straw man here.
Lynch101 said:that allows us to fill in the blanks in our pictures of previous "nows"
Only the events in our previous "nows" that have since entered our past light cone. So this is perfectly consistent with my proposed alternative viewpoint.
A comment: you are using way too many words to belabor simple points. You could have stopped your discussion of this particular point right at the sentence I quoted above, and it would have gotten the point across just as well. Everyone else in this discussion is more familiar than you are with the math of relativity, and none of us get paid for this. Brevity is good.
Lynch101 said:If O1's calcuations are correct, how can an event be influencing other events cuausally, if it hasn't yet happened?
For every pair of events A, B for which O1 (or any observer) knows that A causally influenced B, both A and B are in O1's past light cone. So this is perfectly consistent with my proposed alternative viewpoint.
Lynch101 said:the criteria which you apply for testing events - events in the past light cone - applies equally in a Block Universe
No, it doesn't, because my criterion allows the set of which events are fixed and certain to be different for different events in spacetime. The Block Universe does not.
Btw, the statement I just italicized above is a crucial one, which I made and emphasized in my Insights article, and which I have made and emphasized previously in this very discussion, to make the point that no philosopher who has discussed this issue, to my knowledge, has ever addressed it. It might be a good idea for you to stop and take a step back and think very carefully about that statement, before posting again. It would save a lot of time and avoid us having to go back over and over the same ground, since if your response to that statement is simply "Well, I don't think that is even possible", then there is no more to discuss since we simply disagree on a fundamental point.
Lynch101 said:Contrast this with a presentist universe
To be frank, I don't see the point of discussing presentism any further here. We are not here to elucidate all of the fine points of all of the philosophical interpretations of relativity that have been proposed. I would strongly suggest that we focus discussion on the two alternatives that I discussed in my article: the Block Universe, and my proposed alternative in which only events in our past light cone are fixed and certain. Otherwise we are likely to be here long enough to make the point moot because all of 4-d spacetime will be in our past light cone anyway.
Lynch101 said:The corroborating photo simply shows that, during our 10th birthday other observers observed the same thing, but it doesn't tell us about the state of past events.
It doesn't tell us whether past events "still exist", because that's not a testable question.
It does tell us what happened at past events. If you deny that, then you are denying that our present records can give reliable information about past events, in which case, once again, there is no more to discuss since we simply disagree on a fundamental point.
Furthermore, denying that past events are fixed and certain, which is what you are arguing for here, is pointless if you are trying to argue that relativity requires the Block Universe, since the Block Universe accepts that past events are fixed and certain. The point of disagreement between my proposed alternative viewpoint and the Block Universe, which is really the only substantive point of discussion here, has entirely to do with how to treat events outside of our past light cone. So harping on how to treat events inside of our past light cone, the one set of events that my proposed alternative and BU agree about, strikes me as a waste of time. (See also my remarks about presentism above.)
Lynch101 said:The above doesn't contradict the Block Universe
You. Are. Missing. The. Point.
What was the point of my article? Was it that the Block Universe was false? Go back and read my post about what I said and didn't say in my article. We really need to keep this discussion focused and not continue to get bogged down in irrelevancies. Either there is a valid argument that relativity requires the Block Universe interpretation, or there isn't. You claim there is, or at any rate that you can't see why relativity doesn't require the Block Universe. Arguing that such and such does not contradict the Block Universe says nothing whatever about your claim. So please don't waste any more time doing it.
The rest of your post is just more repetition of the same errors or irrelevancies that I have already pointed out, so I won't bother responding any further to it.