The idea of time travel is that someone (or something) is moving in time (at a different than normal rate), while everyone and everything else goes on as if nothing happened. — SophistiCat
Suppose that the metaphysics behind the A theory of time is correct, is it possible to travel to the year 2024 (or the "future") or the year 2000 (or the "past") or does time travel require the B theory of time to be correct? — Walter Pound
Best I can explain the general stance is that eternalism gives equal ontological status to all events. What that status is isn't necessarily part of the view. My opinion on that is certainly not typical of eternalists. — noAxioms
I thought I was pretty explicit in my comment there, so you either have no understanding, or you refuse to accept the way I am using the word. — noAxioms
So you're not trying to drive it to self-inconsistency, but merely decline to accept it, which is fine. — noAxioms
No one is claiming that space flows. If they did, then you can rest assured that that flow would need to be with respect to something. — Inis
Claiming that space and time are merely the setting for events is B-theory. — Inis
That everything at all times exists (some say exists "simpliciter"); i.e. the block universe theory. — Luke
Couldn't it equally be said that the tensed version of existence is reducible to the tenseless version? — Luke
Presentism is the view that only present objects exist. — A Defense of Presentism, Ned Markosian
If time flows, as A-theory claims, what does it flow with respect to? — Inis
The fact that 'exist' appears on both sides. 'Exist' means 'presently existing'. 'Hot' means has a hot temperature. Those are useless circular definitions. — noAxioms
If I say a T-Rex exists, I mean it is a member of the set of objects contained in the universe. I don't mean it is a member of the set of objects currently contained in the universe. — noAxioms
:brow:I dislike calling it B-theory since that name includes growing block view, which is still presentism. — noAxioms
How so? What's so circular about them?All three of those are circular definitions, and thus not really definitions. — noAxioms
I did my best to describe how I use the word in the tail of my prior post. You didn't comment on it. — noAxioms
What does "is" mean here? I take it that "is" means that it currently is, but then again, I'd think you would have a problem with that so if you have an alternative conception then please take this opportunity to offer one. I still have yet to understand what other sense of "exists" there is if there is one.It means 'is a member of' [the universe], and not just 'is a current member of'. — noAxioms
But as for the run of the mill B-theorist, they'd not ever say that the universe exists now, or it once existed, or will exist. — noAxioms
I think a lot of people see the universe as an object like that, coming into being somehow from non-being, just like every actual object in the universe. I don't. I think it contradicts what a universe should be. — noAxioms
Are you saying you don't understand the view or you simply disagree with it? It's hard to tell from you posts. — noAxioms
You seem to want a different word since you disapprove of it being said that those events 'exist' in the same way that I exist. Then I would still balk at that same word being used to say that the universe exists, since it doesn't seem to be an event or a created object or anything. — noAxioms
There is no 'the present' or 'now' in the view, so I'm not sure what is being referred to with that comment. — noAxioms
A-series terms which leads to nonsense when discussing a B-series view. So "could have done otherwise" is an example of an A version of the definition. — noAxioms
The block view just is (my emphasis). — noAxioms
Problem is that means a second and a year would have the same information content which does not seem right. Clearly more information in a year - the continuum seems paradoxical. Maybe it's one of those concepts that we can conceive of in our minds but never occurs in reality? Reality seems deeply logical and free of paradoxes. — Devans99
What structure does time have if it's not a series of instants? — Devans99
But if an event has no duration it would not exist. 'Now' could not exist if it had zero duration. Think about filming someone for zero seconds - you'd have no film right? — Devans99
I have a couple of arguments for time being discrete rather than continuous (actually similar arguments can be used for discrete space too). Thanks in advance for any feedback.
1. A point in space cannot have size=0 because it would only exist in our minds and not reality (no width; insubstantial)
2. Similarly, the point in time ’now’ cannot have length=0 (if it exists for 0 seconds, it does not exist)
3. Or if a ‘now’ had length=0, then a second would contain 1/0=UNDEFINED ‘nows’
4. So ‘now’ has length >0
5. Can’t be length = 1/∞ because ∞ does not exist (∞ + 1 > ∞ making a nonsense of ∞. Or if you define ∞ + 1 = ∞, implies 1 = 0)
6. So a ‘now’ has a finite, non-zero length. Time is composed of a chain of ’nows’ so time must be discrete
a) Imagine a second and a year
b) By the definition of continuous, both time period are graduated identically (to infinite precision).
c) So there must be the same information content in both (same number of time frames: ∞)
d) But a year should contain more information than a second
e) Reductio ad absurdum, time must be discrete — Devans99
It's continuous, as opposed to discrete? "Gunky" seems to imply a mixture of both. — Metaphysician Undercover
If that is how we must view time then the LNC is meaningless because it requires the notion of an instant of time. Nothing happens in an instant/moment/single point of time. — TheMadFool
That's why I wonder about before-before, which blatantly puts cause well after effect, and in any reference frame. Or at least it does in non-local interpretations. — noAxioms
It has that. Is this something different than Lorentz Ether Theory, because I found no mention of flow in any description of it. Maybe Neo-Lorentz adds that on top of LET.
How could CMB possibly suggest a preferred moment??? A preferred frame, sure, but not preferred moment. The A-Theorists similarly do not base their definition of the preferred moment on the CMB. Their moment is simply 'now'. Easy-peasy.
I do not understand these paragraphs. I think you meant to say preferred frame. What is 'physically distinguished'?
All causes seem to be effects of prior causes, but barring an infinite past, there must be a first cause, uncaused. Surely you've heard of that. Block theory has one, but it is just a (perhaps blank) initial condition. Not sure how becoming is expected to fit into that.
A model is considered time ordered when it proposes that a cause event tomorrow can effect a measurement taken yesterday in the same place? Perhaps I don't know what 'time ordered' means, as used in that article. The one picture in there showed non-local influence arrow in a spooky-action setup, and without a preferred frame, the direction of the arrow would be ambiguous. So maybe that's what they mean by time-ordered: Not that the arrow always points forward, just that it doesn't point either way. In the before-before, it doesn't point in an ambiguous direction. It is consistently pointing backwards. — noAxioms
Section 2 considers time-ordered Leggett models assuming thatone event can be considered the cause (occurring before in time), and the other the effect (occurring later in time). — Antoine Suarez
“Nonlocal realism” (as defined in [1, 5]) fails if experiment proves wrong that one of two non-locally correlated events occurs before and is the cause of the other.
Models assuming that the “realistic” mechanism happens in a single preferred frame even in relativistic experiments with devices in motion, are not refuted by the before-before experiment, but such models bear a fundamental oddity: since they assume that each event has a cause preceding it in time, they actually dispose of the freedom of the experimenter.
Thus, if one wishes to save time-ordered causality one is forced to assume that the outcomes are determined at the beam splitters (like De Broglie and Bohm did). — Antoine Suarez
Only SR says it is undetectable. GR does not, since it isn't just a local theory. There are non-local tests for an isomorphic foliation, which isn't an inertial frame, but seems to be the most viable candidate for some kind of preferred ordering of all events anywhere. — noAxioms
For that matter, I don't understand what possible problem is solved by growing block as opposed to presentism. I looked up the wiki page, and it defined it, but went no further in pointing out a single benefit of it. —
The Minkowski model is one specifically of a block scenario. It is a straight metaphysical interpretation of time, making no empirical predictions distinct from the flowing model. Einstein drew on the mathematics of this model and Lorentz's work in producing his theory of relativity. But yes, the theory of relativity does not itself assert those metaphysics. It just uses the mathematics of spacetime, and refers regularly to spacetime as a unified whole.
Really?? Do any of them suggest another, like the frame of the solar system perhaps? That would suit the purpose of some people that would seem to have a requirement for A-theory.
It does? I wasn't there at the time. Couldn't say.
I find becoming to be difficult to explain, with all the uncaused-cause contradictions.
No frame, preferred or otherwise puts cause before effect in the Bohmian interpretation of before-before results. So I guess I don't understand where the article addresses that. The two events are separated time-like, so there is no ambiguity to their ordering that can be disambiguated with a preferred frame. — noAxioms
From what I read, A-theory includes growing block and presentism, which differ in the ontological status of past events, but both posit the flow of a preferred moment, so all my comments about presentism so far also can be applied to growing block. Perhaps you can explain the distinction if it is more than that.
I'm saying that no QM or relativistic interpretation seems to propose flowing time. I'm probably wrong, but I'm just unaware of one. Some assert a preferred frame, but that isn't flow.
Relativity just says it isn't locally detectable. Non-locally, one does suggest itself, and GR very much acknowledges it. It is the foliation where spatial expansion is symmetric/isomorphic.
The concept of becoming seems required only for the flowing model, but doesn't fit well at all with the block model. That's a good deal of the appeal of the block model is it doesn't need to explain the becoming.
I don't see a description of before/before. I see it named, but not described. — noAxioms
Unfortunately, the before-before experiment (which I didn't see described) very much violates time-ordering since the effect measurement events by Alice and Bob are separated from the cause decision event by Victor in a time-like separation, not a space-like separation.
I'm not sure how Bohmian mechanics describes the before-before experiment. I thought it explained spooky-action through hidden variables, not through time ordered non-local influence, but I don't see how hidden variables can explain before-before.
BTW, none of this directly relates to presentism, or A-theory as you call it.
A preferred frame is not a preferred moment, even if a preferred moment seems to require a preferred foliation if not a frame.
Both chrome and IE show no page, just the download. — noAxioms
OK, but your thoughts were only that it doesn't have collapse. It does. — noAxioms
I might say I support this interpretation, but you'd then say that means I find the other interpretations wrong, and I don't. So I am again agnostic by the way you explain above. To deny other interpretations is to deny that they are inconsistent with themselves. That they are inconsistent with my preferences is evidence of nothing if I have no empirical evidence that my preferences are correct. — noAxioms
Cannot read it. It downloads a pdf with an unreadable font. — noAxioms
Neither of those interpretations require the observer to be a living thing. As I said, a rock will do.
We're getting kind of off-topic here.
A good habit to hunt down critique. Helps point out which parts on which focus should be placed. I do it myself for papers whether or not I agree with them. I'll try to look at that link closer, but a good deal of it is beyond me. — noAxioms
Idealism has to do with relations to consciousness. The relational view, being non-anthropocentric, is relative to anything at all.
Relation interpretation has collapse. Collapse is what makes the red ball real. MWI does not have collapse.
Bohmian mechanics is not refuted by any experiment. I never claimed that. It just denies locality, and so allows effect before cause, as does any interpretation that denies locality. That makes the interpretaion invalid only if you assert otherwise.
You can also look at Tegmark's paper referenced at the top of that answer. It is 400 pages and I think only deals with the dimensionality aspect. — noAxioms
The 'tachyons only' choice? You can publish that if you can think of a way for tachyons to interact coherently to be structure, let alone one that is a life form. The author Mauro seems to think so, but he omits Tegmarks commentary on that. I think Mauro is mistaking the condition for 3 space and 1 time, but everything moves faster than light, not slower.
I think it violates every attempt at a definition of life that I've seen. Perhaps you'd like to give one that would include this timeless configuration of state.
So yes, can be thought of as one collective determined state. I call that soft determinism since the future measurement of some trivial experiment still cannot be predicted even given perfect knowledge of the system and infinite computing capability. It's determinism only because every possible result happens, and that list of results can be (and already is) computable. The relational interpretation is similar, but says the results that were not measured are not real (they didn't happen 'elsewhere'), and is therefore not a deterministic interpretation.
No, there are quantum experiments that seemingly effect past measurements by decisions made in the future of those measurements. The before-before experiment is one of them. Only interpretations with locality explain that without reverse causation. A preferred frame helps not at all. The issue is not ambiguous ordering such as spooky action between two events outside each other's light cones. The issue here is blatant cause after effect between events that are within each other's light cones.
The representation as a dimension would not reflect reality. — noAxioms
If there were no space, then yes, there would be just this linear series of events. But most pairs of events are ambiguously ordered (at least in the eternal model), so time would then not be a series of events.
Time seems to be relevant only to causally related events, so time seem more to be a a product of a structure with causal relationships. That's how I tend to view it at least. YMMV.
I would think not. If there is a present, it is an absolute state, however undetectable, and other abstract slices of the block are simply misrepresentations of reality. There is no arbitrary choice about it. An arbitrary guess if something preferred suggests itself, and yes, it does.
There's a list of stuff that can vary, and a list that cannot. Yes, the cosmological constant is one, and the hardest one to get to a workable value if you're just pulling random values out of your arse. I guess that implies a lot of bubbles.
Try this, which was the first item on my little google of it:
The article I linked gets into this.
Yes, but most of them not macroscopic. We're counting the macroscopic ones here.
Makes no sense to me. You seem to describe a photo of a dog, which is not a living thing. It isn't life if there are no dynamics.
Well, take the relational interpretation then, which has no meaningful state except as measured, and nothing measures the universe (the big bang is a point of view that sees nothing), so the universe has no state, just relations. Everett would say it has solutions to Schrodinger equations. Neither of those has meaningful state. The Bohmian interpretation has it (hard, single-outcome determinism), but it does so at the cost of cause before effect (locality). I personally find the latter more offensive, but that's just my taste.
I am a squishy eternalist. I only take firm stances against positions which don't seem self consistent.
The philosophical positions you are describing is presentism and eternalism, with the former asserting a flowing preferred moment in time separating all events into 3 distinct ontological states of happened, happening, and yet to happen. The latter gives equal ontological status to all events and disallows references to the nonexistent preferred moment. — noAxioms
It is certainly more practical, which is why A-series is used in everyday language and intuition. I can similarly argue that B-series gives a more practical framework in which physics can be discussed. But lacking an empirical distinction between the two, I don't see a proof being likely. Everyday life can be awkwardly described in B-series, and physics can be awkwardly described in A-series.
I can say the same with slices of space. The word 'history' carries an implication of a past, which is a presentist interpretation.
Spacetime has connectivity yes. Calling them slices is from the eternalist interpretation. The presentist would only have the one current state of space, with no other 'slices' to connect with it.
It isn't a dimension at all if time flows.
4D spacetime can have all four axes oriented arbitrarily, so yes, there's one time axis, but its orientation is arbitrary within the confines of the speed of light. Rotate beyond that, and a different axis assumes the role of the time axis.
Entropy defining the direction of the arrow. If entropy stabilizes, there would be no arrow.
Both account for it all just fine.
??? It isn't in either view.
The former has no slices, just a changing 3D state. The latter has a block with no slices other than abstracted considerations that can be oriented any way one chooses, similar to the way the 3D universe has no mandatory choice for the X axis.
From what I've read on inflation theory, this is chance. There are a lot of dimensions and some inflation bubbles have different numbers of macroscopic spatial and time dimensions. So maybe one bubble has 2 spatial and 3 time dimensions.
Only the 3/1 configuration seems to allow the sort of physical mechanics that permits complex structures like atoms to form. Most of those strangely configured bubbles collapse immediately or explode into featureless fog. That 3/1 bit is part of a much longer list of tunings required to allow us to exist.
There is still quantum indeterminacy, so no brute fact implied by the block. A lot here depends on your quantum interpretation of choice. Hard determinism seems to be what you're describing here, and both time interpretations allow it but don't assert it.
I prefer the eternal model, but I don't assert that the presentist model is wrong.
That which we have no knowledge of we should just shut up about. There are plenty of other things that are knowable and about which we can do something. — Bitter Crank
If I find reincarnation depressing, that need not stop you from being enthusiastic about it. Being reincarnated as a slime mold was just not a good thing, back 5862 tears ago, and I still resent it. — Bitter Crank
Keep in mind that the absolute frame is not an inertial one, nor accelerated or anything else. All the things you can do with a frame are not valid even in this absolute non-frame. — noAxioms
I thought about it, and light speed is constant only in an absolute sense. Of course light speed is constant, just as is sound in a stationary medium. But if you are moving at 1/2c, delta real light speed in one direction is .5c, and it is 1.5c in the other. The subjective moving observer will not notice that since he's perhaps measuring round trip, not one direction... So he puts a mirror 300000 km away (they have these), and it takes 0.666 real seconds one way and 2 seconds the other way, which is 2.66 seconds round trip. But his clock runs slow and the mirror appears to be 346000 km away, so it says 2.3 seconds have elapsed and hides the fact that light in one direction moved slower than the other way.
I probably screwed up the maths somewhere, but it was my shot at it. This is what I mean by more complicated to do it in 3D. In 4D, it is just 2.3 seconds for a 692000 round-trip with everything being stationary in its frame. — noAxioms
Interestingly, the first light speed measurements were done in one direction by putting a clock very far away and then syncing a local clock to our image of it as its light arrives here at (unknown at the time) lightspeed. Now you move that distant clock even further away and notice the amount that it gets out of sync. You move it closer again and it appears to catch back up. In this way, light speed was measured by dividing the increase in separation distance by the amount of time the two clocks appeared to get out of sync. No compensation for relativistic implications (all unknown at the time) of accelerating clocks, but good enough for the precision they were after. — noAxioms
And all measurements of time and distance are false as well only if you consider them to describe the 3D metaphysical interpretation. — noAxioms
It is an interesting exercise to do just that. Assume that the train is the thing stationary, which helps one see past the bias that the platform is always the stationary thing. The platform observer detects the two events at once and is equidistant from the marks left by the events. Why is he wrong in concluding simultaneity? — noAxioms
Well, those equations describe a 4D model, even if a 3D interpretation is assumed. — noAxioms
To do it in 3D, each experiment must adjust for inaccuracies of measured mass, length and time since all these are dilated if one is moving. — noAxioms
The train thought experiments assume a non-absolute definition of space, which is incorrect in the 3D model. Incorrect conclusions of event simultaneity are drawn. — noAxioms
That is a metaphysical view, and one that renders the relativity equations so much simpler, but relativity also works in a 3D model (at a massive expense of complexity) so doesn't assert those metaphyiscs. — noAxioms
I don't know how that's made consistent with Relativity, but I guess some of the concepts of spacetime in GR are rejected (replaced by presentist concepts), although not the experimental results. — Marchesk
HG Wells The Time Machine could not be written under a presentist view of time. A machine can't be traveling from the future to kill Sarah Conner or her son, and there is no parallel timeline/universe for Donnie Darko to save his family from the end of the world (or whatever he was doing). — Marchesk
An explanation that posits the existence of objects without explaining where the objects came from is not complete. — Devans99
I’d also argue if we give any of these objects a mind then it has an infinite personal history which is impossible. — Devans99
In addition, those objects require motion to achieve anything useful. What imparted the first motion to be one of these objects? — Devans99
You are still invoking infinity in the time dimension when talking about the physical universe; it leads to paradoxical problems like everything that can exist must of existed and we should all be Bolzman brains... — Devans99