. And #2 should be "depending on the reference frame", not depending on particle motion. Motion
Presentism doesn't comment about how time works in SR. Presentism was around well over a century ago, and SR was not in any way suggested by it. Not sure when the term was coined, since the interpretation is far older than the name needed to distinguish it from alternative interpretations.
What stops the following from being inferred from special relativity: there is no unique objective ordering of events with respect to time. — fdrake
One can just simply treat one reference frame as being privileged over the others as the basis for absolute rest. Now, is it arbitrary to do so? Certainly, but there is nothing stopping us from doing so anyways and this does not conflict with SR as a scientific model.
Totally agree. SR says physics is unchanged in all these different orderings. There is not a unique ordering of my children either. I could order them by height.That there is a unique ordering of events with respect to time is something that is false because of the special theory of relativity. — fdrake
It doesn't follow. What follows is that if it existed, it would be undetectable. There is no premise of its nonexistence. I don't like its existence because it is a needless addition that explains nothing.What stops the following from being inferred from special relativity: there is no objective ordering of events.
Yes, but any frame can be attached to any particle. It is moving in all but one of them. Yes, some object is typically used as a specification of a frame. There is almost no other way to do it. So we all know what we mean by "frame of the train platform" even though the platform exists just fine in the frame of the train. But I think it is sloppy to say clock C dilates relative to object R. It should more correctly say it dilates in the frame of object R, or even more anal, in the frame in which object R is at rest.Reference frames can be attached to moving particles.
It says there is a unique objective ordering, not a unique ordering. None of the SR orderings are objective.I agree that presentism doesn't imply SR. What I'm saying is that insofar as presentism claims that there is a unique objective ordering of events, it is contradicted by SR.
SR doesn't talk about objective orderings, so I don't see how the above can be inferred.What stops the following from being inferred from special relativity: there is no unique objective ordering of events with respect to time. — fdrake
The arbitrariness of the reference frame used for the definition of universal time removes the possibility of interpreting its time variable as a universal time. All reference frames have just as good a candidate for universal time. That is to say: they all suck for it. — fdrake
It says there is a unique objective ordering, not a unique ordering. None of the SR orderings are objective.
Arbitrary, yes, but again, not impossible. There is a difference between the two. To be impossible means that it is in some sense logically contradictory. I do not see that here.
Yes they do. No inertial frame gets near covering the universe, so if there is an objective ordering, it cannot be an inertial frame. SR doesn't say that, but GR does.All reference frames have just as good a candidate for universal time. That is to say: they all suck for it. — fdrake
It's an ontological assertion. Presentism posits not just a real ordering, but also a real boundary between past and future events. Just the objective ordering is not enough. Presentism adds a boundary that traverses the events in objective order.Ok. What differentiates an objective ordering from one in obtaining in a reference frame in special relativity? — fdrake
Logical possibility isn't a particularly good criterion for forming metaphysical postulates. Any metaphysics is likely to be logically possible. Any physical theory is likely to be logically possible. We need a finer net to capture what is relevant. — fdrake
What matters is what SR does to the idea of there being a unique ordering of events (time as the succession)- it shows that there is none. If there is no unique ordering, there can be no unique objective ordering. The class of orderings that agree with all other orderings is empty, so none can be objective. — fdrake
So long as the boundary doesn't get so advanced one place that events happen before their causes, there's no contradiction. Light cones limit the maximum distortion of the boundary.
I can agree that it suggests that there is none, but I will withhold from using strong words like "impossible" here. I believe there is reason from relativity that supports the rejection of presentism, but I think it is a common misconception that relativity is completely incompatible with it.
Great, then the conceptual work is done. It's more justified to believe that SR suggests there can be no unique objective ordering of events than not. — fdrake
Had a hard time following this.This is a fun way to smuggle in an objective ordering without justification. Why would it be contradictory for an event to happen before its cause as viewed from some reference frame? Contained within the series of cause and effect is the universal succession, only this time of equivalence classes of causes occurring before a given ordinate in the series. — fdrake
What stops the following from being inferred from special relativity: there is no unique objective ordering of events with respect to time. — fdrake
If something supplanted the verified predictions of SR that nevertheless had such an ordering, I would believe it. — fdrake
But I think that SR does a lot to undermine the existence of a unique total ordering of events - so I doubt that a conceptual manoeuvre which introduces a universal time without caveats would be a justified one. — fdrake
One property of relativity is that from any given event X, there is a fixed set of events in its direct past and future causal cones, and this set is frame independent. OK, the frame of Zog puts 2017 in my future, but I don't exist in that frame, so no contradiction.
Consistently off topic nonsense. — fdrake
I follow what you wrote and mostly agree. There doesn't exist a valid frame which covers t1 and t2, but Zog is moving (proper distance increasing) by over 4c, which is not a valid velocity, so hence I say Zog doesn't exist in our frame. But it exists in the universe as does its frame, so I hesitate to assert that this frame that is invalid for t1 is nonexistent. Just invalid for t1. Yes, t2 is ordered before t1, and in fact both predate the big bang. This is what happens when you consider an object or frame in the context of an event for which it is invalid.Because this is interesting, let's have some maths for it.
The quantity 'proper time' is invariant between inertial reference frames.
If dτ2>0 between two events occurring at t1 and t2, then the separation between the events is called time-like. This occurs, roughly, when the temporal separation between two events is greater than their spatial separation.
if we wanted to find a frame of reference in which t2 occurred before t1, reversing the inequality here, it would need squared average velocity which can't happen, since it would be higher than c2. So, if two events have a time-like separation, there does not exist an inertial frame which has their ordering reversed. — fdrake
It is meaningless (but not invalid) to reverse the order of simultaneous events. Either way they both happen at once.Another consequence is that all events occur simultaneously for light. The orders can reverse for space like intervals - when dτ2 is negative.
Right. And any pair of events in causal contact can be said to be at the same point in space in some frame, and any pair outside causal contact can be said to be simultaneous events in some frames.Thus, two events can be said to be in causal contact if they are in time-like separation, but not in space-like separation.
Local spacetime collapses to a singularity at light speed. Not sure if it is valid to reference that as a 'perspective'. It is not a valid inertial frame.From the perspective of light, there is no duration. From other perspectives, there is duration.
Oooh.... Example please, because this seems totally implausible. What is 'our history'? Sure, if we colonize distant stars, event ordering starts getting ambiguous, but it doesn't take a distant observer to notice that. So presume our history is confined to this planet, and we're not just talking about milisecond differences that it takes for light to traverse the diameter of the planet. Sure, events on opposite sides of the planet within a milisecond of each other have frame dependent ordering, but again, it doesn't take a distant observer to notice that.A very distant observer moving in a particular way could see our history with some events in a different order. Why should the universe be seen from the perspective of a human, and not a photon or a distant observer (with space-like separation)?
Your thread seems to have been trying to demonstrate that relativity renders presentism a contradiction. Sure, I don't believe it either, but I don't consider it to be a proven thing. I just try not to be in the habit of believing in things that add to a model without explaining any of it better.Sure, logically possible. I ain't believing in it though. — fdrake
Oooh.... Example please, because this seems totally implausible. What is 'our history'? Sure, if we colonize distant stars, event ordering starts getting ambiguous, but it doesn't take a distant observer to notice that. So presume our history is confined to this planet, and we're not just talking about milisecond differences that it takes for light to traverse the diameter of the planet. Sure, events on opposite sides of the planet within a milisecond of each other have frame dependent ordering, but again, it doesn't take a distant observer to notice that.
(2) The ramifications of both relativity theories, like length contraction, time dilation, and the equivalence of mass and curvature distortions should not be treated as arising from 'deficiencies in measurement'. — fdrake
I had to look that up, and the flaw in the criticism was trivial. The barn and pole are treated as simultaneous objects instead of events. Using the latter, there is no paradox.The author displays a parallel misunderstanding of the barn-pole paradox. — Pierre-Normand
Here is perhaps the disconnect between what fdrake has been addressing and what I've been denying, which is the ontological status of duration, or of time. So I think some clarification is needed, because I think the wording you put here is the more standard one.This crude mistake also appears to have led Robbins to a rather confused conception of what it is that it might mean for a duration to be "ontologically real" rather than its being merely perspectival or relative to a reference frame. — Pierre-Normand
I had to look that up, and the flaw in the criticism was trivial. The barn and pole are treated as simultaneous objects instead of events. Using the latter, there is no paradox. — noAxioms
ote: At some point, because Robbins can't grapple with what he sees as the paradoxical implications of his own ill-defined principle of "abstract reciprocity of reference systems", — Pierre-Normand
Here is perhaps the disconnect between what fdrake has been addressing and what I've been denying, which is the ontological status of duration, or of time. So I think some clarification is needed, because I think the wording you put here is the more standard one.
When people ask me if they think time is real, I don't know how to answer since I don't associate ontologly with my understanding. But apparently it is in contrast to 'prespectival', and no, I don't think it is real in that sense. — noAxioms
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