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Absolute motion
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If absolute simultaneity is a feature of presentism, then it doesn't need to be assumed; it's there by default, just as the dynamics, which are not yet understood, are.
Surely if we are to assume that all observations occur in the present moment, we must assume absolute simultaneity, otherwise we'd be left with a situation where different observers disagree upon the present moment.
Leaving the situation as "dynamics, which are not yet understood" leaves a lot to be desired when attempting to describe something.0 -
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citrus burst wrote: »Surely if we are to assume that all observations occur in the present moment, we must assume absolute simultaneity, otherwise we'd be left with a situation where different observers disagree upon the present moment.
Leaving the situation as "dynamics, which are not yet understood" leaves a lot to be desired when attempting to describe something.That makes absolutely no sense.
We don't assume that all observations occur in the present moment, this is self-evidently true; all your experiences and empirical observations occur in your present moment, all mine in mine, and all Morbert's in Morbert's. We don't need to assume that the present moment is the same for all observers, and we don't need to assume that events which are simultaneous in our present are simultaneous for everyone; we only need to acknowledge that events which are simultaneous in our present are simultaneous in our present.
So, if we start with the self-evident fact that all experiences and empirical observations occur in the present moment, for every observer. We take the observation of the constancy of c and we're left with the question of "how?", for which an explanation is required. Now, if we don't assume that the present moment is the same for everyone, we simply acknowledge that our own experience occurs in the present; if we don't assume that hidden dynamics are the cause, then we are still left with the question of how; if we don't adopt the assumption of past and future, then what is left is presentism and, by default, hidden dynamics.
Our disagreement "over the present moment" is then seen in a different light, it wasn't really a disagreement over the present moment, it was an issue of measurements made in the present moment. We still don't need to assume absolute simultaneity, we only need to acknowledge that all of our experiences and observations occur in the present moment, for us; we acknowledge that other observers are present in our present moment, and that we are present in theirs; the disagreement over simultaneity wasn't really a disagreement over simultaneity in the end, but an issue arising from the measurement of a constant c, which is attributable to hidden dynamics, when we simply don't adopt the assumption of a co-existent past and future.
As an explanation, hidden dynamics does leave a lot to be desired, it leaves us with the desire to know what those hidden dynamics are; but that just means that there is an aspect of the universe, or reality, that we don't yet understand. I think this is more preferable to assuming our conclusions.0 -
That is an assumption. In the scientific sense anyway.We don't assume that all observations occur in the present moment, this is self-evidently true; all your experiences and empirical observations occur in your present moment, all mine in mine, and all Morbert's in Morbert's. We don't need to assume that the present moment is the same for all observers, and we don't need to assume that events which are simultaneous in our present are simultaneous for everyone; we only need to acknowledge that events which are simultaneous in our present are simultaneous in our present.
And how do you write that mathematically to make predictions to test?So, if we start with the self-evident fact that all experiences and empirical observations occur in the present moment, for every observer. We take the observation of the constancy of c and we're left with the question of "how?", for which an explanation is required. Now, if we don't assume that the present moment is the same for everyone, we simply acknowledge that our own experience occurs in the present; if we don't assume that hidden dynamics are the cause, then we are still left with the question of how; if we don't adopt the assumption of past and future, then what is left is presentism and, by default, hidden dynamics.
Please explain.Our disagreement "over the present moment" is then seen in a different light, it wasn't really a disagreement over the present moment, it was an issue of measurements made in the present moment. We still don't need to assume absolute simultaneity, we only need to acknowledge that all of our experiences and observations occur in the present moment, for us; we acknowledge that other observers are present in our present moment, and that we are present in theirs; the disagreement over simultaneity wasn't really a disagreement over simultaneity in the end, but an issue arising from the measurement of a constant c, which is attributable to hidden dynamics, when we simply don't adopt the assumption of a co-existent past and future.
But we do know what these hidden dynamics are.As an explanation, hidden dynamics does leave a lot to be desired, it leaves us with the desire to know what those hidden dynamics are; but that just means that there is an aspect of the universe, or reality, that we don't yet understand. I think this is more preferable to assuming our conclusions.
I have a few problems with Presentism
From what I can gather, it allows certain irregularities that cannot be explained in any shape or form. (These are not the same as the hidden dynamics)
It seems to suggest that two observers, due to their present moments might arrive at different outcomes from the same casually connected events due to their present moments being different. I'm talking big like disagreeing over whether Pluto exploded or not. I'm not 100% sure on this will need more time to think about it.
My biggest issue is that it seems to not allow anything to actually happen in the universe. Take velocity for example, [latex]v=\frac{x_2-x_1}{t_2-t_1} [/latex]. Now from what I can gather, since all observations occur at one time point, the present, we can never actually figure out if something moves or not. This is a huge problem in my eyes.
Also not relevant to my reply, but probably relevant in some way or another to this and the other threads, here is a nice picture of S (left) in terms of S' (right).
http://imgur.com/gallery/TR9W5GN0 -
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Then it would be a scientific assumption which is self-evidently true.citrus burst wrote: »That is an assumption. In the scientific sense anyway.
That I'm not sure; how would you mathematically model presentism, given that it is a possibility which is compatible with relativity? It seems to get mentioned that it is essentially the mathematics of Lorentzian relativity.citrus burst wrote: »And how do you write that mathematically to make predictions to test?
If presentism is compatible with relativity, then we can look at RoS through the lens presentism and see that it has two possible interpretations; one which is at odds with absolute simultaneity and one which isn't; that is, assuming that absolute simultaneity goes hand in hand with presentism.citrus burst wrote: »Please explain.
This means that RoS can be interpreted as a relativity of measurements, as opposed to a relativity of the simultaneity of events; time dilation would be attributable to the mechanics of the clock, not the effect of physical time slowing down.
So, if presentism is compatible with relativity, then the observers disagreement isn't necessarily over the present moment, it's an issue stemming from the hidden dynamical effects on measuring instruments.
What are they; is it due to the motion of the instruments with respect to an undetectable Aether?citrus burst wrote: »But we do know what these hidden dynamics are.
I'd question whether they would disagree over whether Pluto exploded or not, I would imagine that the issue lies in the timing of the explosion.citrus burst wrote: »I have a few problems with Presentism
From what I can gather, it allows certain irregularities that cannot be explained in any shape or form. (These are not the same as the hidden dynamics)
It seems to suggest that two observers, due to their present moments might arrive at different outcomes from the same casually connected events due to their present moments being different. I'm talking big like disagreeing over whether Pluto exploded or not. I'm not 100% sure on this will need more time to think about it.
I think there tends to be some confusion over what presentism is, it is sometimes interpreted to mean that everything occurs in a single moment in time; but that isn't the case, because time isn't taken to be something physical or existent; things don't happen "in time". The present moment is continuously evolving and changing, things move relative to each other, they just don't move "through time".citrus burst wrote: »My biggest issue is that it seems to not allow anything to actually happen in the universe. Take velocity for example, [latex]{t_2-t_1} [/latex]. Now from what I can gather, since all observations occur at one time point, the present, we can never actually figure out if something moves or not. This is a huge problem in my eyes.
Presentism doesn't preclude the use of clocks as a measuring apparatus, what is questioned is what is actually being measured by the clocks; presentism would suggest that physical time is not being measaured, rather the clocks provide a repetitious cycle which can be used for comparing other processes with each other.
You would still have [latex]{t_2-t_1} [/latex] where t would still be the values given by a clock.
Is the picture on the left just a normal picture taken from a moving train, or is it adjusted for relativistic effects do you know?citrus burst wrote: »Also not relevant to my reply, but probably relevant in some way or another to this and the other threads, here is a nice picture of S (left) in terms of S' (right).
http://imgur.com/gallery/TR9W5GN0 -
We don't assume that all observations occur in the present moment, this is self-evidently true; all your experiences and empirical observations occur in your present moment, all mine in mine, and all Morbert's in Morbert's. We don't need to assume that the present moment is the same for all observers, and we don't need to assume that events which are simultaneous in our present are simultaneous for everyone; we only need to acknowledge that events which are simultaneous in our present are simultaneous in our present.
So, if we start with the self-evident fact that all experiences and empirical observations occur in the present moment, for every observer. We take the observation of the constancy of c and we're left with the question of "how?", for which an explanation is required. Now, if we don't assume that the present moment is the same for everyone, we simply acknowledge that our own experience occurs in the present; if we don't assume that hidden dynamics are the cause, then we are still left with the question of how; if we don't adopt the assumption of past and future, then what is left is presentism and, by default, hidden dynamics.
Our disagreement "over the present moment" is then seen in a different light, it wasn't really a disagreement over the present moment, it was an issue of measurements made in the present moment. We still don't need to assume absolute simultaneity, we only need to acknowledge that all of our experiences and observations occur in the present moment, for us; we acknowledge that other observers are present in our present moment, and that we are present in theirs; the disagreement over simultaneity wasn't really a disagreement over simultaneity in the end, but an issue arising from the measurement of a constant c, which is attributable to hidden dynamics, when we simply don't adopt the assumption of a co-existent past and future.
As an explanation, hidden dynamics does leave a lot to be desired, it leaves us with the desire to know what those hidden dynamics are; but that just means that there is an aspect of the universe, or reality, that we don't yet understand. I think this is more preferable to assuming our conclusions.
Premise 1) All experiences and empirical observations occur in the present moment, for every observer
Premise 2) The speed of light is the same for all observers.
Presentism does not follow from these premises. Instead, you need a third premise.
Premise 3) All observers agree with what events are occurring in the present.
Premise 3 is not self-evident.0 -
Premise 1) All experiences and empirical observations occur in the present moment, for every observer
Premise 2) The speed of light is the same for all observers.
Presentism does not follow from these premises. Instead, you need a third premise.
Premise 3) All observers agree with what events are occurring in the present.
Premise 3 is not self-evident.
Premise 3 isn't required; an alternative is that observers simply don't disagree over what events are occurring in the present. This is achieved by changing the second premise to:
the measurement of the speed of light is the same for all observers.
Here observers disagree over measurements, not the ordering of events. If the measurements cause them to disagree over the ordering of events, then at least one of them must be assuming past and future. If they don't assume past and future, they're left with presentism and there is no dispute over the order of events.
So, observers don't need to assume that the present is the same for all observers, they only need to acknowledge that other observers, who populate their present moment, disagree over measurements. Hidden dynamics are used to explain the constancy of the measurement, and no dispute over the order of events arises. The hidden dynamics appears to be the necessary conclusion, when past and future are not assumed.0 -
Premise 3 isn't required; an alternative is that observers simply don't disagree over what events are occurring in the present. This is achieved by changing the second premise to:
the measurement of the speed of light is the same for all observers.
Here observers disagree over measurements, not the ordering of events. If the measurements cause them to disagree over the ordering of events, then at least one of them must be assuming past and future. If they don't assume past and future, they're left with presentism and there is no dispute over the order of events.
So, observers don't need to assume that the present is the same for all observers, they only need to acknowledge that other observers, who populate their present moment, disagree over measurements. Hidden dynamics are used to explain the constancy of the measurement, and no dispute over the order of events arises. The hidden dynamics appears to be the necessary conclusion, when past and future are not assumed.
You haven't challenged my previous post at all. If premise 3 is not assumed then they can either conclude their measurements of the speed of light are trustworthy, and that simultaneity is relative, or they can assume a set of hidden dynamics that conspire to make measurements of the speed of light the same for all observers.0 -
If I am stationary with respect to roosh, then we would agree with what is the present no matter how far away I was.
And I think roosh would say that that is the shared present, shared with each other.
The time-slice also represents the wave-front of experience, doesn't it? What we feel as 'now' is actually due to the process of having an experience of some kind. Would you agree?
If we look at it this way then we are in fact gaining experience as the consecutive time-slices unfold. Everyone everywhere would be gaining their experience 'now' and would all share the same time-slice as they did so.
I take it you would agree with this in the case that all observers are stationary relative to one another.
Which clearly isn't the case in the real world where everything is in fact moving relative to everything else.
Suppose that roosh is looking at the clock because he and I are performing an experiment concerning moving clocks. We each have identical and synchronised clocks that can transceive and process data. I, along with my clock are in a craft that can travel very quickly.
At 12:00, for reasons not relating to the exploding sun, I accelerate away from roosh at a velocity which causes my clock to tick at half the rate of his, i.e., when his clock reads 12:02, mine reads 12:01.
So, we have the situation where, when roosh's clock turns to 12:08 and he says 'Oh Sh..!', you are observing roosh as he was at 12:07 his time and I am whizzing through space believing that roosh's clock reads 12:04.
Now, I would constitute a set of events that are mapped out in your 'shared now' and according the 12:08 (roosh's time) time-slice, I exist as a set of events that thinks it is 12:04.
Conversely, in the time-slice where my clock reads 12:08, neither you nor roosh would exist but had it not been for the supernova, roosh's clock would read 12:16 and you would be viewing him as he was at 12:15, his time. (What's up with that anyway. )
If every possible configuration of the universe has an associated time-slice and each time-slice represents all the matter and energy in the universe then it follows that 'now' is in fact the only time-slice that can be experienced.
Further, it follows that the time-slices are effectively charting out the interactions between energy and matter - if each time-slice represents all the energy and matter of the universe then the only time-slice that actually exists is the 'now' one. The future is what 'now' is changed into and it is the 'stuff of now' that is changing. And the past is what the 'stuff of now' was like before it changed and exists only as memories and photographs.
So the past, present and future of the universe is an infinite succession of 'now' time-slices. At least according to perception. But what's the reality?
If the past and future exist simultaneously the there is actually no such thing as 'now' in terms of being any particular time-slice since all time-slices are in the past or present all other time-slices. In this sense, past and future are simply the opposite direction away from any given point in time.
I'm thinking of an old vinyl LP on a gramophone. The entire surface of the disk is the set of time-slices representing all of time. Each point on the disk represents a unique time-slice. But where is now on the record?
For that matter, what distinguishes the future from the past on the record?
I would say that we need a 'now' in order to define a past or present of any point in time and for humans, it is experience that demarcs the two. Without establishing what 'is', we can't assess what 'was' or deduce what 'will be'.
In order to know how far away from me you are I first need to know where I am. 'I am' is what I experience. I have to designate a 'now' in order to make 'Where will you be at five?' and 'Where were you at two?' have meaning. If I don't get now right, I must surely get 'then' wrong too.
The past and future are directions away from where we are. And equally, they are directions away from what we are and we are really nothing more than a succession of uncountable events. More importantly though, we only exist as events actually occur.
(I find it odd to think of myself as being like a flame, made up of entirely different events at every moment. We truly are like sparks.)
But where are 'we' on the gramophone? Where is now and how can it be experienced? We need to start the record turning and put the needle onto the groove. Only then can the time-slices be experienced and a 'now' established.
Now, we can see the entire record on the turntable and at the same time we hear what is coming out of the speaker and it is this combination that allows us to deduce that the entire region of the groove behind the needle is the past and the region of the groove is in front of the needle.
In this analogy we have an example of how the past and future co-exist and of how 'now' is a fairly arbitrary assignation.
The block-universe now seems reasonable. It is basically a gramophone playing a very long-playing record. Not only that but there is a built in directionality of the groove along a time-line. If we include a mechanism that make the record play in a constant loop then we have the equivalent of a block-universe, don't we? All time-slices exist and all time-slices are experienceable?
And to make it more accurate, we can imagine the record-playing mechanism as a perpetual-motion machine and, in order to rule out an uncreated force, let's say that the needle has always been in contact with the groove.
And anything that isn't a part of the gramophone isn't part of the universe.
Okay, so there is always going to be the question of how did a complete and fully functioning sound-system come to spontaneously appear in the void but I'm actually just trying to head the deterministic objections off at the pass.
And this is problematic for determinists, isn't it? I mean, we can argue about the notion of perpetual motion but I would not be so quick to dismiss perpetual motion if it were defined as a mechanism that derives its own energy. That would be a weak objection.
We might say 'yeah but the record represents an infinite number of points each of which rerepresent the entire mass of a universe and that would mean the record alone represents the mass of the universe multiplied by infinity... And what's more, the record player is even bigger and therefore the block-universe must be very massive as a whole - what keeps it together?' but again, I would say that we don't know conclusively yet that 'mass' is an actual thing as opposed to just an effect.
And anyway, you might counter with an explanation that says that we experience the universe precisely because the block-universe is so massive it has blown itself apart, etc., etc.
Another thing against us is that, sticking to the gramophone analogy, we are effectively saying that the only part of the groove that actually exists is the part directly below the needle, that the universe is just one point that interacts with the needle in such a way as to appear a groove on a turntable that is turning from the needle's perspective.
I think that the best objection I can raise is 'but surely there is wear and tear... each time the needle passes the same point, it alters it slightly and eventually all the information will be lost. Where is the past and the future now?'
But 'now' would still exist and 'now' will have a future. In the absence of information, 'now' is the creator of information. Quantum fluctuations of 'now' give rise to the quantum fluctuations of the future and 'now', as always, will create its own past. And for as long as the needle is on the record and the turntable is turning.
When all information is gone, the last datum must be first datum, the origin of what follows.
It still seems to me that we can do away with a coexistent past and future in favour of one datum, or one time-slice, and determinism.
Whilst I do like the time-slice thing, I just don't see how it can explain why we experience 'now' in a way that appears to be 'directional', from young to old and never the other way around.
If we start from there there, one configuration of the universe and determinism then absolute motion is implicit. Things move and observation confirms this.
If experience can be likened to processing data then how could that occur without any moving parts?0 -
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The third premise isn't required, because in order to conclude the former they must assume co-existent past and future; in order to conclude the latter all they have to do is not make that assumption.You haven't challenged my previous post at all. If premise 3 is not assumed then they can either conclude their measurements of the speed of light are trustworthy, and that simultaneity is relative, or they can assume a set of hidden dynamics that conspire to make measurements of the speed of light the same for all observers.
All they are required to do is acknowledge that events which are (non-)simultaneous for them are (non-)simultaneous for them; their relatively moving counterpart, who is in their present moment, makes a different set of measurements; they don't have to assume that the events are (non-)simultaneous for everyone, they just need to explain why there are different measurements. Only by assuming past and future do they arrive at the conclusion that simultaneity is relative; without those assumptions the different measurements are attributed to dynamics which they don't understand, without ever assuming absolute simultaneity.
That there is a single present moment shared by all observers is self-evidently true, if we simply don't assume that the past and future exist; because if we don't assume past and future, all that is left is the present. The existence of past and/or future isn't self-evidently true if we don't assume presentism, they must still be assumed by every single observer.
Another way of looking at it is, if presentism isn't true then we are left with the following possibilites:
- past and future exist
- past exists but future doesn't
- future exists but past doesn't
All of those require an assumption on behalf of every observer that either the past or the future, or both exist;so, neither the existence of the past or the future is self-evidently true if we don't assume presentism, whereas presentism is self-evidently true if we don't assume past and/or future.
Simply by not assuming an existential past and future we are left with presentism and dynamics that we do not understand.0 -
The way I look at it, we have to pick one of the five assumptions (you only mentioned four).Another way of looking at it is, if presentism isn't true then we are left with the following possibilites:
- past and future exist
- past exists but future doesn't
- future exists but past doesn't
All of those require an assumption on behalf of every observer that either the past or the future, or both exist;so, neither the existence of the past or the future is self-evidently true if we don't assume presentism, whereas presentism is self-evidently true if we don't assume past and/or future.
Simply by not assuming an existential past and future we are left with presentism and dynamics that we do not understand.
- only the present exists
- past and future exist
- past exists but future doesn't
- future exists but past doesn't
- they all exist
Each has compelling pro's and con's. I don't really care which is true as long as they are consistent. Personally I'd pick 3 or 5.0 -
Presentismcitrus burst wrote: »The way I look at it, we have to pick one of the five assumptions (you only mentioned four).
- only the present exists
- past and future exist
- past exists but future doesn't
- future exists but past doesn't
- they all exist
Each has compelling pro's and con's. I don't really care which is true as long as they are consistent. Personally I'd pick 3 or 5.
You don't have to assume that only the present exists; you only need to acknowledge that you only ever experience the present moment; this is self evidently true. You don't need to assume that the present moment you occupy is the same for all observers, but that doesn't mean that you assume that it is different either; you don't assume either way.
In order to conclude that the present moment isn't the same for all observers you have to assume that past and/or future exist; in order to conclude that it is the same for all observers, all you need to do is not make that assumption. So, from your experience of your present moment, simply by not assuming past and/or future exist you are left with presentism. If you don't "assume" presentism, you are left with a possibility of alternatives, all of which require you to make an assumption about them.
Absolute Simultaneity
Similarly, we don't need to assume absolute simultaneity; if absolute simultaneity is a necessary condition of presentism, then simply not assuming past and future also gives us absolute simultaneity. Now, it might be tempting to think that, just like past and future we also have to assume absolute simultaneity, but that isn't true; it only seems true when we think RoS is an option, but by considering RoS as an option we necessarily have to assume that past and future exist.
Theoretically, what we would have, is a set of measurements which are at odds with each other. Without any assumptions of past, future, or absolute simultaneity, we are left needing an explanation for how observers measure the same speed of light regardless of their motion relative to the source. In order to conclude that RoS is the answer, we have to assume that past and future exist; if we don't assume that past and future exist we are left with presentism, and a set of dynamics which are not understood accounts for the discrepancy in the measurements and the issue of simultaneity was never really an issue in the first place.
Time
The issue of simultaneity is probably, in no small part, attributable to our assumptions about time, of which past and future are an integral part. When we say that events are simultaneous if they "happen at the same time", then how we view "time" affects our interpretation of simultaneity. How we view "time" also affects our interpretation of how clocks work; if we assume that clocks measure something physical called "time", then the discrepancy between the measurements, which requires the explanation, carries a different interpretation. If, however, we examine how a clock operates and discover that nowhere in the process is something physical called time actually measured, then we can start to question the nature and existence of time. If we have no evidence of the existence of time, or at least, no evidence that time is a physical property of the universe - that doesn't require us to assume it a priori - then our definition of simultaneity as being "events which happen at the same time" has a different interpretation.
If clocks don't measure time, then the disagreement over measurements isn't a disagreement over the simultaneity of events; it only becomes one with the additional assumption that time is physical and that a clock measures that physical property - which would represent and additional assumption which is required.0 -
The third premise isn't required, because in order to conclude the former they must assume co-existent past and future; in order to conclude the latter all they have to do is not make that assumption.
All they are required to do is acknowledge that events which are (non-)simultaneous for them are (non-)simultaneous for them; their relatively moving counterpart, who is in their present moment, makes a different set of measurements; they don't have to assume that the events are (non-)simultaneous for everyone, they just need to explain why there are different measurements. Only by assuming past and future do they arrive at the conclusion that simultaneity is relative; without those assumptions the different measurements are attributed to dynamics which they don't understand, without ever assuming absolute simultaneity.
That there is a single present moment shared by all observers is self-evidently true, if we simply don't assume that the past and future exist; because if we don't assume past and future, all that is left is the present. The existence of past and/or future isn't self-evidently true if we don't assume presentism, they must still be assumed by every single observer.
Another way of looking at it is, if presentism isn't true then we are left with the following possibilites:
- past and future exist
- past exists but future doesn't
- future exists but past doesn't
All of those require an assumption on behalf of every observer that either the past or the future, or both exist;so, neither the existence of the past or the future is self-evidently true if we don't assume presentism, whereas presentism is self-evidently true if we don't assume past and/or future.
Simply by not assuming an existential past and future we are left with presentism and dynamics that we do not understand.
Not assuming X is not the same as assuming X is false. If you don't assume the existence of spacetime, you are left with observers experiencing their present moments, and observers measuring the speed of light to be c. People can then either a) Accept these measurements as real, and conclude relativity of simultaneity and the existence of spacetime, or b) Posit dynamics which conspire to make everyone measure the speed of light to be c, no matter how they do the measurement, and conclude the possibility of presentism.0 -
The problem is when we consider observers moving relative to us. They would not agree with us about the present moment.
We don't disagree on this and we must surely agree that the fact that light has a finite speed predicts this. I cannot know about you now until I find out later.
This seems obvious now, the fact that information cannot be received and transmitted simultaneously suggests as much.
However, if one were to consider the time-slice where it is 12:04 for me, then that same time-slice would contain the events that are roosh at 12:08 and you observing roosh at 12:07.
And in the time-slice where you are observing roosh at 12:07, my clock would read 12:04 while roosh's clock reads 12:08.
In other words, if I were to map out a time-slice at my 12:04, and you were to map out a time-slice at your 12:07 and roosh was to map out a time-slice at his 12:08, then all three of us should create identical maps.
No? If not how not?0 -
Premise 1) All experiences and empirical observations occur in the present moment, for every observer
Premise 2) The speed of light is the same for all observers.
Presentism does not follow from these premises. Instead, you need a third premise.
Premise 3) All observers agree with what events are occurring in the present.
Premise 3 is not self-evident.
Well no because if you have premise 1 then premise 2 need neither be present and nor even to be true. Causality emerges from premise 1 and all that needs to be realised is that light has a finite speed, that information cannot be simultaneously transmitted by one system and received by another and therefore, even if the speed of light is not the same for all observers, premise 1 predicts that not all observers will agree with what events are occurring in the present.
Premise 1 actually dismisses premise 3 which is self-evident.
In fact premise 1 predicts that it is impossible to accurately measure the speed of light since all photon absorbers are in motion relative to the path of any emitted photon, i.e., there will always be a small amoun't of spectral shift of a photon's energy regardless of who makes the measurement. Even the same apparatus in the same experiment will yield different results at different times.
The other thing that is self-evident from premise 1 is absolute motion. The process of change is the story of motion, photons being emitted and absorbed, collisions, the movement of energy is what gives rise to reality. If nothing moved then nothing would change.
If premise 1 can be boiled down to the assumption that there is one 'time-slice' and that that time-slice is experienced by all the observers on it then determinism emerges.
If we remove the concept of time from this altogether, we are left with a slice, a slice that represents the entire set of events that comprise the universe as they occur. The slice would be dynamic by nature since it would actually reflect the process of change and regardless of time.
And only systems that are comprised of events occurring now can experience the universe as it is.
If we start with premise 1 and thermodynamics, the only thing that is unexplained is 'motion' and how it came about.
Or, to put it another way, the only question left for the determinist is, 'Why did it move?'0 -
Observers don't need to assume that the present moment exists*, it is self-evident that it does; but to conclude that more than that exists requires the assumption that it does. To conclude that nothing more exists, simply requires observers not to make that assumption that more exists; because, either more exists, or it doesn't.Not assuming X is not the same as assuming X is false. If you don't assume the existence of spacetime, you are left with observers experiencing their present moments, and observers measuring the speed of light to be c. People can then either a) Accept these measurements as real, and conclude relativity of simultaneity and the existence of spacetime, or b) Posit dynamics which conspire to make everyone measure the speed of light to be c, no matter how they do the measurement, and conclude the possibility of presentism.
Either, or
Either the present moment is all that exists* or one of the following is true; simultaneity is relative and the present moment co-exists with:
- the past and future
- the past
- the future
or
simultaneity is absolute and the present co-exists with:
- the past and future
- the past
- the future
So, even if we assume that the present moment isn't all that exists*, or don't assume the positive form of that proposition, we still don't arrive at the conclusion of spacetime. We require further assumptions, not least assuming that either past and/or future exist.
I'm wondering is it entirely arbitrary which we assume exists, or does spacetime necessitate that both must exist, or that either the past or the future must exist; that is, that all observers must make those particular assumptions. The growing block theory would suggest that an observers past can exist without their future existing, but would it be possible to have a shrinking block, where only the future exists and the past decays as an observer progresses through it?
neither, nor
Now, given that either the present moment is all that exists* or past and/or future exist, and that the existence of past and/or future must be assumed, simply not making the assumption of past and/or future leaves the observer with the conclusion that the present moment is all that exists.
This is because neither past, nor future are necessary conclusions of assuming the present isn't all that exists; if we assume that more than the present exists, then we still have to make a positive assumption about the conclusion; we must positively assume that either the past, the future, or both exist.
So, not assuming past and future leaves you with presentism, but not assuming presentism doesn't specifically leave you with one of the following:
- past and future exist
- the past exists
- the future exists
By assuming past and future alone, you still don't necessarily arrive at the conclusion of spacetime, but simply not assuming past and future leaves you with presentism, because it's either or. Simply not assuming past and future leaves you with presentism, which means that the conclusion of hidden dynamics is reached.
* We are talking about from the perspective of any given observer.0 -
Observers don't need to assume that the present moment exists*, it is self-evident that it does; but to conclude that more than that exists requires the assumption that it does. To conclude that nothing more exists, simply requires observers not to make that assumption that more exists; because, either more exists, or it doesn't.
Either, or
Either the present moment is all that exists* or one of the following is true; simultaneity is relative and the present moment co-exists with:
- the past and future
- the past
- the future
If simultaneity is relative, then the past and future must exist.or
simultaneity is absolute and the present co-exists with:
- the past and future
- the past
- the future
So, even if we assume that the present moment isn't all that exists*, or don't assume the positive form of that proposition, we still don't arrive at the conclusion of spacetime. We require further assumptions, not least assuming that either past and/or future exist.
I'm wondering is it entirely arbitrary which we assume exists, or does spacetime necessitate that both must exist, or that either the past or the future must exist; that is, that all observers must make those particular assumptions. The growing block theory would suggest that an observers past can exist without their future existing, but would it be possible to have a shrinking block, where only the future exists and the past decays as an observer progresses through it?
neither, nor
Now, given that either the present moment is all that exists* or past and/or future exist, and that the existence of past and/or future must be assumed, simply not making the assumption of past and/or future leaves the observer with the conclusion that the present moment is all that exists.
This is because neither past, nor future are necessary conclusions of assuming the present isn't all that exists; if we assume that more than the present exists, then we still have to make a positive assumption about the conclusion; we must positively assume that either the past, the future, or both exist.
So, not assuming past and future leaves you with presentism, but not assuming presentism doesn't specifically leave you with one of the following:
- past and future exist
- the past exists
- the future exists
By assuming past and future alone, you still don't necessarily arrive at the conclusion of spacetime, but simply not assuming past and future leaves you with presentism, because it's either or. Simply not assuming past and future leaves you with presentism, which means that the conclusion of hidden dynamics is reached.
* We are talking about from the perspective of any given observer.
If we assume relativity of simultaneity is the correct interpretation of experimental observations and Lorentz transformations, then both the past and the future must exist. This is tedious to show mathematically, but not difficult if you would like to see it.
So my original description is still valid: Each observer experiences a present moment, and each observer measures the speed of light to be c. For these two experiences to be the same for all observers, there must be either new dynamics and absolute simultaneity, or spacetime and relativity of simultaneity. Neither is more empirical than the other.0 -
The point was more taking a look at the "assumption" of presentism and the possibilities we are left with, if we don't assume the present moment is all that exists. Not assuming presentism, or even assuming that the present moment is not all that exists, doesn't necessarily give us spacetime, because past and future could both co-exist with a present moment which is shared by all observers.If simultaneity is relative, then the past and future must exist.
If we assume relativity of simultaneity is the correct interpretation of experimental observations and Lorentz transformations, then both the past and the future must exist. This is tedious to show mathematically, but not difficult if you would like to see it.
I don't think there's need to go through the mathematics; I think we can work off that premise anyway.
On a related note though, is growing block theory not a viable possibility also?
Each observer experiences their present moment and measures the speed of light to be c. Now, either:So my original description is still valid: Each observer experiences a present moment, and each observer measures the speed of light to be c. For these two experiences to be the same for all observers, there must be either new dynamics and absolute simultaneity, or spacetime and relativity of simultaneity. Neither is more empirical than the other.
a) their present moment is all that exists and new dynamics is responsible for the constancy of c;
or b) past and future co-exist with a shared present and the new dynamics are still responsible;
or c) RoS and spacetime are the conclusions.
In short, either their present moment is all that exists or their past and/or future also exist. To conclude that past and future exist, they must assume that they do. If they don't make those assumptions, then they are left with the conclusion that their present is all that exists and a) above.
Even assuming that past and future exist, they are still left with options b) and c), which means that there must be a further assumption required to distinguish between them. That assumption, I would think, is the assumption that a clock measures a physical property called time.0 -
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The point was more taking a look at the "assumption" of presentism and the possibilities we are left with, if we don't assume the present moment is all that exists. Not assuming presentism, or even assuming that the present moment is not all that exists, doesn't necessarily give us spacetime, because past and future could both co-exist with a present moment which is shared by all observers.
I don't think there's need to go through the mathematics; I think we can work off that premise anyway.
On a related note though, is growing block theory not a viable possibility also?
You have it slightly backwards. Assuming a common present moment does not necessarily rule out spacetime. Instead, spacetime merely becomes a superfluous assumption. If we do not share a common present moment, then spacetime must exist.
Growing block theory would not be compatible with RoS because the Lorentz transformation of simultaneity is somewhat analogous to a stick. If one end is pushed across someone's future, then the other end must be pushed across someone's past. E.g. The "now slices" (the lines labelled with x, x', and x'') in the picture below.
Each observer experiences their present moment and measures the speed of light to be c. Now, either:
a) their present moment is all that exists and new dynamics is responsible for the constancy of c;
or b) past and future co-exist with a shared present and the new dynamics are still responsible;
or c) RoS and spacetime are the conclusions.
In short, either their present moment is all that exists or their past and/or future also exist. To conclude that past and future exist, they must assume that they do. If they don't make those assumptions, then they are left with the conclusion that their present is all that exists and a) above.
Even assuming that past and future exist, they are still left with options b) and c), which means that there must be a further assumption required to distinguish between them. That assumption, I would think, is the assumption that a clock measures a physical property called time.
This is also reversed. b) Can be dismissed immediately. It is simply a) with an extra, unnecessary assumption about spacetime. Therefore the choices are a) or c). One says dynamics are responsible for everyone being able to measure the speed of light to be c. The other says spacetime is responsible.0 -
Apologies, by spacetime I meant Minkowski spacetime; the idea that spacetime isn't ruled out if there is a common present moment is reflected in option b) above.You have it slightly backwards. Assuming a common present moment does not necessarily rule out spacetime. Instead, spacetime merely becomes a superfluous assumption. If we do not share a common present moment, then spacetime must exist.
Do you know, are there still physicists who are attempting to develop a growing block theory; just out of interest?Growing block theory would not be compatible with RoS because the Lorentz transformation of simultaneity is somewhat analogous to a stick. If one end is pushed across someone's future, then the other end must be pushed across someone's past. E.g. The "now slices" (the lines labelled with x, x', and x'') in the picture below.
The point is that assuming more than the present moment exists doesn't necessarily give us Minkowski spacetimme; it is possible that past and/or future co-exist with a shared present. In order to arrive at the conclusions of either Minkowksi spacetime or a spacetime where the present moment is shared by all, requires, not only, the assumptions of past and future, but a further assumption on both counts. The latter is no more unnecessary than the former. In both cases the conclusions have to be assumed.This is also reversed. b) Can be dismissed immediately. It is simply a) with an extra, unnecessary assumption about spacetime. Therefore the choices are a) or c). One says dynamics are responsible for everyone being able to measure the speed of light to be c. The other says spacetime is responsible.
Option a) however, doesn't require such assumptions. Again, either presentism - the idea that only the present moment exists - is true, or else past and/or future exist. For an observer to arrive at the conclusion that more than their own present moment exists, they must assume the conclusions of past and/or future. Simply not assuming such conclusions leaves the observer with presentism, and dynamics that they don't understand. This is true even when the options are only a) and c).0
This discussion has been closed.
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