I had mentioned the rock above. Yes, it very much is a measurement. Thing X (source of photon) has now caused an effect on said rock, and X now exists to the rock. That's how QM measurements work. It causes the state of X and the state of the rock to become entangled. The special equipment in labs is only special because it records the measurement precisely for the purpose of the knowledge of the lab guys, but measurement itself is trivial.This would be like saying that light hitting a rock is an act of measurement. — Metaphysician Undercover
We have different definitions of measurement. I'm speaking of measurement in the QM wave-function collapse sort of way. That interaction is 'actually measuring it'.Of course measurement requires processing, it is a process. You cannot measure something without actually measuring it. — Metaphysician Undercover
Yes, I figured that was the definition under which you were working. I'm not talking about knowing.Measuring creates a knowing. If there is no knowing, then there has been no measuring.
I don't see how any of that doesn't occur in all frames of reference. Maybe I don't understand how you're using the term. I'm interpreting it as 'inertial frame of reference' but maybe you mean POV or something, except no POV is specified then.Wouldn't you agree that the movements of my arms and legs ought to be understood as occurring in a different frame of reference from the movements occurring within the neurology of my brain, and my nervous system?
It takes time to gather all information about the spread-out state into one point (said future event) which can be anywhere, not necessarily an event that is part of me.Why would this event, which measures all the defined states as one state, need to be in the future of those states? Can't the different defined states just be compared as occurring in different frames of reference? — Metaphysician Undercover
Measurement doesn't require processing. The light hits me somewhere (eyes, toenail, whatever) and I've measured the moon. It exists to me now. The processing is only necessary for me to know it exists, but knowing doesn't define existence except under idealism where the photon never hit me at all.The light hitting your eyes is processed, and the image is created. — Metaphysician Undercover
All (reasonably local, like not outside the Hubble Sphere) parts exist in all frames.What do you think it means for an entity not to exist all at one place? Could one part of that entity be in one frame of reference, and another part be in another? — Metaphysician Undercover
Quite true, but it is still at least 'right here', or at least as much as 'here' can be defined for an entity which doesn't exist all in one place.I wouldn't say that this is "right now", because the image is created, and that takes time. The light hitting your eyes is processed, and the image is created. So even the light from the moon hitting your eyes is in the past by the time you see the image. — Metaphysician Undercover
Under presentism, there is no hypersurface or light cone, both 4 dimensional concepts. So if you seek information about any of the simultaneous events that make up your present, you have to wait for the information to come to you, at which time the information is no longer about the present.Your present hypersurface is inaccessible to you. If you seek information about any of the simultaneous events that make up your present, you have to wait for the information to become part of your past light-cone. — Inis
The observing is done in your present, but what is observed is only right here, nowhere else. I cannot see the present moon, but I see light in the image of moon right now. That light is right here, and from that image, I deduce a moon in the past and infer the moon still being there in the present, totally unmeasured. This process is automatic and not usually noticed. Andrew M points this out.But I still observe the objects in my present. — Echarmion
What you refer to is probably a proposed objective present. In that scenario, present reality is observer independent, and the present defines you, not the other way around. That present is not reference frame dependent, and thus reality is the same for everybody (as it should be for any observer-independent stance).Either we are referring to an objective present, in which case all information I currently observe refers to an objective past, or we are referring to my subjective present, in which case I can observe objects in my present.
Your present is not necessarily 'the present'. In fact, quite unlikely to be. Presentism is safe from this sort of argument in my opinion.If this person is real, and independent of you and your present, relativity tells you that she also has her own present, which is as real to her as your present is to you. Your presents are not the same. Presentism is false. — Inis
Ditto with presentism, which also has states in between, else it is a series of discreet jumps.Aristotle demonstrated, that if you describe such changes in terms of states, you'll always need an intermediate state between the two states, to account for the change. — Metaphysician Undercover
Yes. That quote does not say there is no motion or no time. It just says time doesn't flow in that model.Did you not see the quote I posted on the previous page of this discussion:
The resulting timeless cosmos is sometimes called a “block universe” — a static block of space-time in which any flow of time, or passage through it, must presumably be a mental construct or other illusion.
It seems quite clear to me. — Luke
The article never says that there is no motion under anything. The word in fact never appears.I think that there is "no motion under eternalism" from everything I've read about it. It also states the same in the article I linked to in my previous post. Eternalism is synonymous with the block universe. — Luke
Sounds to me like you traveled about a year into the future, just like we all do. Travel into the future seems effortless. It's not doing it that's the trick.In other words, with the current method, you can leave earth for a year to travel in time, and when you come back after a year for you has passed, on earth a year and one minute will have passed. — Tomseltje
I know of two premises of SR (one of which predates the theory by several centuries), and a third for GR. None of them are "All things change place as time passes".All things change place as time passes, it's a premise of relativity. — Metaphysician Undercover
Exactly, just as the twin that takes a side trip to some other star and back is not measuring the duration between the two events of departure and return.And that's not what your claiming, because taking a side trip around another tree is not measuring the distance between yourself and the tree. — Metaphysician Undercover
I can measure the distance between myself and that tree over there, and get an indeterminate value because one of the measuring tapes takes a path around that other tree to the left over there, and thus measures a different distance. So all measurements are indeterminate in that sense. But I could have calculated how each of those measurements would come out ahead of time. Those measurements are fixed before they are done, as opposed say to quantum measurements which are not predictable in advance.Indeterminate means without a fixed value. If the quantity of time measured between when the twins separated, to when they reunited, varies from one frame of reference to another, it is without a fixed value, and is therefore indeterminate. — Metaphysician Undercover
Events are fixed (by definition), not frame dependent at all. They're points in spacetime, and don't have frame dependent qualities such as velocity, duration, or length and so on. Their light cones are determined by light speed, not the frames, so those are also fixed.I think you are wrong to say that the light cones are not frame dependent. Any event has a light cone. According to SR, the present of an event, or time that an event occurs, is frame dependent. Therefore the light cone for any event is frame dependent. — Metaphysician Undercover
This is a feature of your future light cone. That cone, not the present, delimits events which can and cannot be changed.It is one of the most fundamental aspects of our experience, that past events are substantially different from future events. Past events cannot be changed, while we can influence the occurrence of future events. — Metaphysician Undercover
I think you have a different concept of presentism than the one typically presented on philosophy sites, which might ask when the twins get back together and notice 10 or 20 years elapsed, isn't one of them more correct about how many years actually went by? Presentism would say yes to that, but you seem to say no, since a different amount time passed for each of them, so they're both right about it.I don't see why presentism requires a preferred reference frame. When we as human beings meet together, and communicate, we call this the present. We only need to produce a reference frame if we want to measure the passing of time. Presentism doesn't necessarily require this, so it doesn't require a preferred reference frame. — Metaphysician Undercover
Determinacy is unaffected by any choice of foliation. Different frames of reference do not in any way alter the causal relationship between any two events.A "preferred foliation" might validate determinacy in time, if the preferred foliation was justified, not arbitrary. But if the preferred foliation were justified, wouldn't special relativity be contradicted? — Metaphysician Undercover
You seem to use 'indeterminate' as 'not absolute'. The word means 'uncalculable', or 'unpredictable', and as Terrapin has been trying to point out, it is quite calculable. These things are just frame dependent, but completely determined given a choice of frames.Right, there is a combined value of time and space. However, since what is actually measured by us, according to our capacities, is time, and space independently, and these are indeterminate, then the combined value is fundamentally indeterminate. — Metaphysician Undercover
It is called a preferred reference frame, or at least a preferred foliation (an objective ordering of events). Presentism must assume such a thing, but the existence of a preferred foliation does not necessarily imply the existence of a present (a preferred moment).If I assumed a "Master Time", then I couldn't conclude that time is indeterminate. — Metaphysician Undercover
In the spacetime model, there is no concept of 'point in time'. Time is just one of 4 dimension, all of which need to be specified to identify a point, which is called an event. There is a fixed (frame independent) separation of any two events, but that separation is called the interval, not the duration between them. Both the time and the space between any two events is frame dependent (indeterminate), but the combination of the two (the interval) is always the same.Can I make the further, more generalized conclusion, that the amount of time between any two points in time, is indeterminate? — Metaphysician Undercover
No clock or other device measures objective time, so this doesn't follow. All clocks run slow, and some slower than others, so it is to be expected that they don't always agree.We know that an objective present cannot exist because the clocks disagree. All there can be are relative presents. — Inis
I don't think any of those theories assert it, despite the typical interpretation of relativity. I know Einstein held eternalist views due to the implications of the theory, but that's mostly because it is the simpler view, without a needless addition that adds nothing to the theory.Eternalism isn't metaphysical if it's part of our best physical theories. — Inis
I actually don't follow what you're trying to say here. I don't know what it would mean to say that the universe is not at rest (has a nonzero velocity???), so there doesn't seem to be any meaning to saying it is at rest.Both general relativity and quantum mechanics tell us that the universe as a whole is at rest. This was realised early on in GR but took a while to be understood in QM.
This means that presentism isn't metaphysical either, it's just wrong.
Yes, that would be a metaphysical claim, and one independent of the eteralism/presentism debate. The latter concerns the nature of the universe (is it 3D or 4D?), but the former is something deeper, and seems to rest on a sort of undefined meaning of 'exists'. Being a relativist, I don't make sense of something being said to just 'exist'. It exists in relation to something (which need not be an observer), and I'm not sure in relation to what the universe might be said to exist or not exist. So such statements need to be defined by those that makes such statements.What is metaphysical, however, is the claim that an objective observer-independent Reality exists.
If 'I' am an observation, that observation is taken at some event, and that means 'I' am an event, in relation which 'the present' very much has meaning. If 'I' constitutes a defined series of specific events, then those events are not simultaneous and none of the events is more special than any of the others, except perhaps the two endpoints. 'The present' could still be defined as the last event of the series of events that defines 'I'. Presentism is not wrong there, and the cost doesn't seem too high.If you take the view that reality is observer-dependent, then presentism may be rehabilitated, but at what cost?
One clock runs slower than the other. — noAxioms
Apparently I was responding to a different quote, the one just below the one quoted in that response. It is about how time dilation doesn't invalidate presentism.I'm not sure how this relates to what I've said. — Luke
Presentism and Eternalism are two different metaphyscial interpretations of the same empirical data. Since time travel would be an empirical experience, it should in principle make zero difference whether presentism or eternalism is assumed. Under current empirical physics, both metaphysical views forbid time travel to the past, and neither forbids forward travel. Hence I see little point in needing to assume one metaphysical stance when discussing if a physical act is possibility or not.Again, I think we need to assume presentism (or that "the A theory of time is correct") for the purposes of the topic of this discussion. However, if you all just want to discuss the failings of presentism then have at it.
Hey, we actually agree on a point...I don't see how the reading on the clock has anything to do with whether or not the present exists. — Metaphysician Undercover
Well, I buy into neither presentism nor time travel, so I'm trying to imagine how a presentist would envision travel to a time that is no longer existent. Somehow you need to find yourself in a world with the state being some prior state except for you being in it, which sort of seems to require a physical rewind of all state (except the part where 'you' appears in it), thus dragging the present back to that prior time. It really makes no sense to me, but it makes no sense in the block view either, so go figure.What do you mean "they rewind"? — SophistiCat
Well relativity gets you that, and it even looks normal to the 'travelling' person.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.
I don't think it makes sense for a presentist to propose a divergence of time. A divergence of worlds, sure. That avoids some paradoxes, but time going forward for Fred but backwards for me in my machine, no. If my machine does that, then it just creates a new world now that looks like my old world did X years ago, without actually alter the course of 'the present'.But how this divergence is possible if there is only one now is something I can't wrap my head around. It would make sense if now diverged as well.
One clock runs slower than the other. Neither of them tracks the pace of the advancement of the present. If there was a device that could do that, you'd have your empirical evidence for the view.How about doing a simple time dilation experiment? Synchronise atomic clocks, and take one on a flight around the world. When the clocks are reunited, they no longer agree on the time. How is that possible under presentism? — Inis
Yes they do, all other factors being equal.Clocks in different time zones don't run at different rates. — Inis
Well, they 'rewind' along with the rest of 'history', which isn't even a violation of physics. Only what you (the 'traveler') are doing is a violation."I presume you ride the 'now' into the future. That's how it worked. To travel to the past, I suppose you'd have to get time to go the other way, and still be able to ride it, but leaving everybody else behind."
— noAxioms
This works for the Traveler, but what about the rest of us? What happens to us and our now when the Traveler departs into the future or the past, and now departs with him? — SophistiCat
Pretty much the standard depiction, yes. I think Back to the Future did almost exactly this.We can imagine a world in which, in the year 2019, you stepped into the time machine and suddenly disappeared. Earlier, in the year 1919, an exact copy of you as of 2019 suddenly appeared in a field, fooled around for, say, a week, and then disappeared. Meanwhile, in the year 2019, five minutes after vanishing in the time machine, you reappear, having the memories and other physical changes that your copy had in 1919 at the time of disappearance.
I think it very much counts if there is a guy in 1919 with memory of 2019. The way you tell the story puts emphasis where the storyteller wants it, but there would be little dispute of time travel to somebody with such memories in 1919, however little he might be able to convince the locals there.We could tell the same story chronologically, without jumping back and forth between 2019 and 1919. The reason we usually tell these stories achronologically is to emphasize causal connections. But in this telling there are no anomalous causal connections between the past and the future - and that is why it does not count as time travel. Time travel is all about anomalous causality.
I presume you ride the 'now' into the future. That's how it worked. To travel to the past, I suppose you'd have to get time to go the other way, and still be able to ride it, but leaving everybody else behind.Thinking a bit more about this, if now is an objective fact on presentism, and the Time Traveler is transported some ways into the past or the future, what happens with the now? — SophistiCat
I always wondered what meaning there is being a unit of X per X, which seems to reduce to just unitless '1'. On the other hand, our clocks are dilated mostly due to the gravity well in which we find ourselves, so maybe the rate is still unitless, but still less than 1. How much less is an eye-opening exercise.normal "time travel" when everyone moves forward into the future in lockstep at 1 second per second — SophistiCat
If there is no distinction between the present and other times, then yes.Suppose I am an ontological nihilist who believes that nothing exists, including events. In that sense, all events have the same ontological status, that of not existing. Would that count as "eternalism" then under your view? — Mr Bee
I've defended the opposite side of that argument. I don't think relativity contradicts presentism, however much I think presentism is nonsense. The two view make all the same empirical predictions, and theory of relativity is an empirical theory, not a metaphysical interpretation.there simply is no choice but to be a B-theorist since the discovery of relativity. Presentism simply doesn't work. — Inis
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.The reason why I have been using "currently" is because that is the only way I can make sense of your claims, but I very much welcome an alternative conception, so long as it makes sense. Indeed, that is the very reason why I am having this discussion with you. — Mr Bee
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
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. By your insistence in adding 'currently', you are assuming presentism, so of course non-presentism isn't going to be compatible with that.I still do not see how you're using the term "is" in a manner that isn't present tensed though. Also what exactly is in the "set of objects contained in the universe"? I assume that it is going to contain the set of objects that are currently contained in the universe. — Mr Bee
My question is what other meaning of "exists" could there be if it doesn't refer to "presently existing", "did exist" or "will exist". — Mr Bee
All three of those are circular definitions, and thus not really definitions. — noAxioms
The fact that 'exist' appears on both sides. 'Exist' means 'presently existing'. 'Hot' means has a hot temperature. Those are useless circular definitions.How so? What's so circular about them? — Mr Bee
It means 'is a member of' [the universe], and not just 'is a current member of'. — 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.What does "is" mean here?
I dislike calling it B-theory since that name includes growing block view, which is still presentism.I have an understanding of the B-theory and the A-theory of time which I believe captures the essence what most people understand the view to be. That version of the B-theory I also happen to disagree with but that is not something I will go into here. — Mr Bee
All three of those are circular definitions, and thus not really definitions.My question is what other meaning of "exists" could there be if it doesn't refer to "presently existing", "did exist" or "will exist".
I can agree that I find little meaning to the block universe existing or not. I see no need for distinction between the two. 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. Any of those is like saying it is located to the left of the invisible pink unicorn: a relation with an entity not acknowledged.What I am saying is that first part of your sentence, that there is no "present" or "now" doesn't make sense. There is no meaning to the idea that the "block universe exists" without stating that it either exists now, did exist, or will exist. — Mr Bee
History is littered with such statements. Are you the only one that is correct about it?Just look at our conversation right now, for instance which is embedded in the now.
Fine. Pick another word, and that word also probably should not be used, since it is a word used for objects. Does the last ice age exist? It is part of the history of Earth, as is the process where the sun swallows it. 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.As a result, I believe that all views about time are "presentist" to the extent that everything that is said to "exist" is presently existing. It is sort of trivial, but that is what "exists" technically means (as again, it is a present tense term).
No tensed verbs for starters. The universe cannot be a created object for instance. There is no 'there was no universe, and then later there was'. If that happens, there are two kinds of time, and you're talking a different view. The other kind if time is the one that the deity lives in, except then the deity lives within something he didn't create, so that's a problem, but not my problem.Well, what sort of non A-series terms are there? — Mr Bee
There is no 'the present' or 'now' in the view, so I'm not sure what is being referred to with that comment. OK, you use 'present' as a verb, so perhaps you mean some other declaration of being. To be honest, the view doesn't assert 'presence' at all since none of the view seems to require it. The angles of a square are all right angles whether or not the square is present. I've thus never really asserted it. I'm quite in the minority on that point since everybody presumes that presence, but it is a premise, not something that can be proven without assuming the conclusion.I actually think the attempt to remove A-series terms from a description of the B-series is what leads to nonsense (such as this whole "triviality problem" that people are currently discussing about the A vs. B theories of time). Just take what you said later as an example:
The block view just is (my emphasis).
— noAxioms
What could the "is" mean other than that it is present, or that it exists now (both being A-series terms)?
B-series descriptions should simply not make reference to the present, which has no meaning in the view. All of Terrapin Station's comments made reference to it, so they're A-descriptions.Of course, I imagine you don't want to say that you mean that by your use of the term, but what else could it possibly be? A tenseless use of the term? What could that possibly mean?
I've also seen 'proofs' that the presentist view cannot be, but they all seem to be faulty.Now as for my own views on the matter, I think that the B-theory of time does make alot of A-series terms irrelevant, but does not eliminate them altogether. The idea that things "will happen" or "did happen" make no sense in a world where time doesn't pass.
That would be two times: The one in which the block is created, and another that is a dimension of the block. Eternalism is not a view of there being two kinds of time.You can't get outside of it with because either the block of time always was there or there was nothing and then time suddenly appeared. — Terrapin Station
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
Both "appeared out of nowhere" and "always existed" are A-series references, which of course are incompatible with B series. The block view just is. There is no 'beginning to exist' of it, because that puts time outside the block, which is not how the view depicts time.With B time, you still have the problem (for intuition) that it either appeared "out of nowhere" or always existed. — Terrapin Station
As an ontological principle, it demands a preferred frame. Without that, two events cannot be actually simultaneous. TOR does not assert that preferred frame, so it makes no such ontological assertion.One key principle upon which special theory of relativity rests, is the relativity of simultaneity. As I explained above, it is an ontological principle. — Metaphysician Undercover
Agree, but theory of relativity is not an ontological principle. The standard interpretation is, but you can't use its premises in a different interpretation.In general, competing ontological principles are incompatible and there is no easy test to falsify one or the other. — Metaphysician Undercover
