So these facts about an event are subjective: they depend on when in time you are when you are making the judgement.
You’re describing a B-theoretical perspective. An A-theorist will disagree with this characterization. Many A-theorists believe that the only objects that exist are present objects. So time isn’t like space, where “here” is “here” rather than “there” simply because you happen to be “here” and not “there”. You could have been “there”, in which case “there” would have been “here” for you. Time, A-theorists claim, is different, because you couldn’t be located anywhere (anywhen) else except in the present. It’s not that the present is the present for you because you happen to be there; it’s that the only time at which objects exist (and, by extension, you could exist) is the present. So it’s not like there are other people who exist at other times, for whom the present is different.
Don’t ask me to defend this view, though, because I think it’s nuts. A-theory vs. B-theory is one of those philosophical debates which should be declared closed. B-theory has clearly won.
I don’t think anyone’s made A-theory consistent with special relativity. But you can bodge general relativity/cosmological models a bit to get something that looks a bit like A-theory by insisting on a preferred foliation (e.g. look at spacelike surfaces with constant proper time since the Big Bang, and count everything on one such surface as the “real now”)
Bourne, from what I recall, makes A-theory consistent with special relativity by positing that there is an (undetectable) privileged reference frame. Is this correct? If it is, I wouldn’t really call that “consistent with special relativity”, more like “flying in the face of the central lesson of special relativity”.
Yeah, that’s basically right but I’m not sure that you’re being entirely fair to Bourne.
First, I think under standard definitions of consistent, he does show that an A-theory is consistent with SR (ie. they can both be true at once).
Second, I’m not sure it’s fair to say that he is “flying in the face of the central lesson of SR”—he may be flying in the face of the standard way of interpreting this lesson but his claim is precisely that this way of intrepreting the lesson isn’t the only way. The lesson can also be interpretted as “no privileged reference frame can be detected.”
I agree with the basic anti-Bourne sentiment but wonder whether the wording of your response undermines his claims more than they deserve—I don’t think they are inconsistent nor that they fly in the face of the central lesson. I guess I more just think that postulating undetectable physical features of the world in order to make a metaphysical thesis - that is based on intuition (the “present” intuition) that can be explained away—come out to be true is undesirable.
Though it should be noted that Bourne’s conclusion is mostly that presentism is the only sensible A-theory but that it’s not possible to decide between presentism and a B-theory (that is, he doesn’t argue that presentism must be true).
So this is just like the “bodge” I described for general relativity/cosmology, but with even less justification? The preferred foliation has no physical motivation at all, and is plucked entirely out of the aether (so to speak).
I’m not sure I’d count that as consistent with special relativity. Though in principle it would give the same predictions as special relativity.
You’re describing a B-theoretical perspective. An A-theorist will disagree with this characterization. Many A-theorists believe that the only objects that exist are present objects. So time isn’t like space, where “here” is “here” rather than “there” simply because you happen to be “here” and not “there”. You could have been “there”, in which case “there” would have been “here” for you. Time, A-theorists claim, is different, because you couldn’t be located anywhere (anywhen) else except in the present. It’s not that the present is the present for you because you happen to be there; it’s that the only time at which objects exist (and, by extension, you could exist) is the present. So it’s not like there are other people who exist at other times, for whom the present is different.
Don’t ask me to defend this view, though, because I think it’s nuts. A-theory vs. B-theory is one of those philosophical debates which should be declared closed. B-theory has clearly won.
I don’t think anyone’s made A-theory consistent with special relativity. But you can bodge general relativity/cosmological models a bit to get something that looks a bit like A-theory by insisting on a preferred foliation (e.g. look at spacelike surfaces with constant proper time since the Big Bang, and count everything on one such surface as the “real now”)
See Craig Borne “A Future for Presentism” for someone who claims to have made an A-theory consistent with special relativity.
Bourne, from what I recall, makes A-theory consistent with special relativity by positing that there is an (undetectable) privileged reference frame. Is this correct? If it is, I wouldn’t really call that “consistent with special relativity”, more like “flying in the face of the central lesson of special relativity”.
Yeah, that’s basically right but I’m not sure that you’re being entirely fair to Bourne.
First, I think under standard definitions of consistent, he does show that an A-theory is consistent with SR (ie. they can both be true at once).
Second, I’m not sure it’s fair to say that he is “flying in the face of the central lesson of SR”—he may be flying in the face of the standard way of interpreting this lesson but his claim is precisely that this way of intrepreting the lesson isn’t the only way. The lesson can also be interpretted as “no privileged reference frame can be detected.”
I agree with the basic anti-Bourne sentiment but wonder whether the wording of your response undermines his claims more than they deserve—I don’t think they are inconsistent nor that they fly in the face of the central lesson. I guess I more just think that postulating undetectable physical features of the world in order to make a metaphysical thesis - that is based on intuition (the “present” intuition) that can be explained away—come out to be true is undesirable.
Though it should be noted that Bourne’s conclusion is mostly that presentism is the only sensible A-theory but that it’s not possible to decide between presentism and a B-theory (that is, he doesn’t argue that presentism must be true).
So this is just like the “bodge” I described for general relativity/cosmology, but with even less justification? The preferred foliation has no physical motivation at all, and is plucked entirely out of the aether (so to speak).
I’m not sure I’d count that as consistent with special relativity. Though in principle it would give the same predictions as special relativity.