From the human perspective, there is a variable amount of time between any two moments in time depending on the frame of reference. — Metaphysician Undercover
But time isn't indeterminate in a particular frame of reference. — Terrapin Station
It's just relative--due to factors such as velocity--when you compare different frames of reference. We can predictively calculate those differences to a high degree of precision, which wouldn't make much sense if it were indeterminate. — Terrapin Station
I know, but the human perspective gives us the potential for infinite frames of reference. Therefore from the human perspective, time is 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
I never said anything about "psychological time". I'm talking about time itself. From the human perspective, time is 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). — noAxioms
Anyway, under the preferred foliation, there is a fixed amount of time between any two moments in time, and frames which do not correspond to this preferred frame are simply not representative of the absolute ordering of events. Hence clocks are all wrong because they're all dilated, some more than others. — noAxioms
In the spacetime model, there is no concept of 'point in time'. — noAxioms
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. — noAxioms
But that's not true. Again, we can know that on the ground, clocks are going to read, say, 500 hours on the nose, while on the space station, clocks read, say, 499-point-whatever (I don't know what the exact difference is--I'd have to research it) hours relative to the 500 hours on the ground.
How is that indeterminate? — Terrapin Station
One clock measures 499, the other measures 500. Therefore the amount of time between those two points is indefinite. — 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
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
Literally everything in relative motion inhabits a different present. These presents become more strikingly in disagreement as relative speeds increase and with distance. A classic example of this is Penrose's Andromeda Paradox, inappropriately named, because it is not a paradox. — Inis
So I may conclude that from the point in time when Bob left, to the point when Bob returned, the amount of time which passes is dependent on one's frame of reference. Can I make the further, more generalized conclusion, that the amount of time between any two points in time, is indeterminate? — Metaphysician Undercover
This makes no sense to me. If the one reads 500 hours on the nose and the other reads 499 hours, 58 minutes and 30 seconds, then the amount of time between those two is not indefinite, it's a minute and 30 seconds. That's very definite. — Terrapin Station
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. — noAxioms
SR just says no preferred folation is locally detectable. It doesn't forbid its existence. — noAxioms
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. — noAxioms
This is a feature of your future light cone. That cone, not the present, delimits events which can and cannot be changed.
Similarly, the past light cone, not the present, delimits that about which we can know (events which can have an effect on us, vs those which cannot).
Neither of these fundamental things changes at the boundary of the present, except where the two cones happen to intersect the present. So no fundamental change as described here occurs at the present.
Those light cones are not frame dependent. They are 'determinate' as you put it. — noAxioms
No, it is determinate. This is just arithmetic (the amount of time between t1 and t2 is t2 - t1). Note that to specify times at all is to assume a particular reference frame. Normally we don't have to think about this because we (and most matter in the universe) age at about the same rate (because we move at similarly slow speeds relative to the speed of light). — Andrew M
Since there is an infinity of possibilities, to the amount of time between that beginning point and the ending point, that amount of time is indeterminate. — 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
Obviously not, because Bob measures the time between t1 and t2 as 6 years, and Alice measures the time between t1 and t2 as 10 years. Therefore the quantity of time between t1 and t2 is indeterminate. — Metaphysician Undercover
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. — noAxioms
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
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. — noAxioms
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
The point is that there is a multitude of possible amounts of time between the first point and the second. Therefore the amount of time between those two points is 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). — noAxioms
Anyway, under the preferred foliation, there is a fixed amount of time between any two moments in time, and frames which do not correspond to this preferred frame are simply not representative of the absolute ordering of events. Hence clocks are all wrong because they're all dilated, some more than others. — noAxioms
It's only indeterminate if you're looking for an overaching time perspective, which is why I brought that up first. — Terrapin Station
Indeterminate means having no fixed value. So consider this analogy. Some one asks you what time it is. By the time you say what time it is, it is no longer that time. So "what time it is" has no fixed value, and time is inherently indeterminate. — Metaphysician Undercover
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
Anyway, the subject of the thread implies that one's interpretation of time has anything to do with the possibility of time travel. Assuming time travel is to the past, as is typically assumed, it is impossible, period. A-theory has nothing to do with that. — noAxioms
Such a concept would involve sending information to the past, and that has never been possible under any valid interpretation of physics. — noAxioms
Alternatively, presentism may dispense with an observer independent objective reality. — Inis
https://www.quantamagazine.org/a-debate-over-the-physics-of-time-20160719/Many physicists argue that Einstein’s position is implied by the two pillars of modern physics: Einstein’s masterpiece, the general theory of relativity, and the Standard Model of particle physics. The laws that underlie these theories are time-symmetric — that is, the physics they describe is the same, regardless of whether the variable called “time” increases or decreases. Moreover, they say nothing at all about the point we call “now” — a special moment (or so it appears) for us, but seemingly undefined when we talk about the universe at large. 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.
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