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Does time exist?

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Comments

  • #212
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    roosh wrote: »
    That we cannot establish it as a logical necessity does not mean we are free to reject it, because, of course, we can deduce that it might actually exist; we just cannot tell one inertial state from another. We can, however, distinguish between them logically. Of course though, the physically indistinguishable nature of motion only extends to inertial motion; we can, apparently, distinguish accelerated motion from non-accelerated motion.

    Yes it does. Or to put it another way: There is no compelling logical argument for absolute, intrinsic motion. You keep reasserting that there is, but you never tender an argument that doesn't tacitly assume it to begin with.
    We mightn't need to go any further though; from Maxwell's equations we can only deduce that the measurement of c remains invariant, not necessarily the actual speed of light as represented by those measurements.

    Where length contraction and time dilation are involved, two measurements of 300,000km/s mean that only the measured speed of light remains invariant, not the actual speed.

    This is contrary to Einsteinian relativity.

    I'm not sure about the idea of a "bar of smoke", but it might be more accurate to say that atoms have to contract by different amounts, and all processes are slowed by different amounts, depending on their intrinsic motion; assuming there is not other, simpler explanation for the lack of a fringe shift in interferometry experiments.

    With Einsteinian relativity we only need to assume that time is physical; that a clock measures time; that past and future exist; that the actual speed of light remains constant; that the one-way speed of light is the same in all directions, regardless of the motion relative to the source; that mathematical reference frames have physical existence; that static world-lines can somehow give rise to relative motion; that we exist as worldlines; that a clock can tick both faster and slower than another clock; and that nothing is actually capable of movement.

    Or, to put it another way, that the relation between events exhibits hyperbolic geometry, which can contract and dilate, without affecting the dynamics of the phyiscal objects that are contracted.

    You don't need to assume such things in Einstein's relativity. They are all a consequence of the kinematics of hyperbolic geometry. I.e. Einstein's relativity, unlike Lorentz's, has an underlying principle that provides a structure for all observations.

    But do you agree that, at the very least, Lorentzian relativity, and hence presentism, is based on assumptions?


  • #213
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    Morbert wrote: »
    Yes it does. Or to put it another way: There is no compelling logical argument for absolute, intrinsic motion. You keep reasserting that there is, but you never tender an argument that doesn't tacitly assume it to begin with.
    There is, equally, no compelling logical argument against it; what we have is the conclusion that we cannot tell between different states of inertial motion, meaning that we cannot tell if an object is at absolute rest, or in a state of absolute, inertial motion.

    You're taking this to mean that absolute motion doesn't exist, but that isn't a justified conclusion; you're trying to justify it on the basis that absolute rest is the same as absolute inertial motion, and so we can conclude that absolute rest doesn't exist, and with it absolute motion; but we cannot conclude that absolute rest doesn't exist, because, for all we know the Earth could be at absolute rest.

    And even if absolute rest didn't exist, it would simply mean that no object in the universe is in a state of absolute rest, all objects are absolutely in motion. That doesn't mean we can't hypothesise about the possibility that an object could find itself at absolute rest - indeed, the Earth might just be at absolute rest - and use the mathematical construct for the purpose of deduction.


    In short, the idea that nothing in the universe is at absolute rest, and all things are absolutely in motion, but that it is, theoretically, possible for objects to be in a state of absolute rest, is closer to what is a justifiable conclusion from the experimental test of the principle of relativity, than the conclusion that absolute motion doesn't exist at all.


    Morbert wrote: »
    You don't need to assume such things in Einstein's relativity. They are all a consequence of the kinematics of hyperbolic geometry. I.e. Einstein's relativity, unlike Lorentz's, has an underlying principle that provides a structure for all observations.

    But do you agree that, at the very least, Lorentzian relativity, and hence presentism, is based on assumptions?
    They are all supporting assumptions, and things we have to assume to be true, if we are to accept the kinematics of Einsteins hyperbolic geometry.

    I would agree that there are assumptions in Lorentzian relativity, for example the existence of a preferred, universal reference frame that determines the universal time. I do, however, believe that such an assumption can be removed from Lorentzian relativity simply by recognising that mathematical reference frames don't exist in reality, and that no object has to actually be at absolute rest; we only need to be able to speak about a hypothetical, imaginary absolute reference frame for the purpose of deduction, not for measurement. The need for an absolute reference frame, to define universal time, is further negated when we recognise the fact that time doesn't actually exist.

    As for the mysterious dynamics, I don't think they are any more mysterious than the idea of a hyberbolic geometry which gives the illusion of a mysterious dynamics, without actually affecting the dynamics; I just think the mysterious dynamics require us to make fewer assumptions that run contrary to our empirical experience of the world.

    I don't, however, believe that presentism is based on an assumption; I know that I have never experienced anything other than the present moment, and I think if everyone is being honest, then neither has anybody else.

    You might say that we have to assume that we share the same present, but I don't think this is accurate, because for it not to be the case every observer has to assume that their past continues to exist, and that their future already exists - this would run contrary to their empirical experience of the universe. In the absence of these assumptions about past and future, all we are left with is the present moment.


  • #214
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    roosh wrote: »
    There is, equally, no compelling logical argument against it; what we have is the conclusion that we cannot tell between different states of inertial motion, meaning that we cannot tell if an object is at absolute rest, or in a state of absolute, inertial motion.

    You're taking this to mean that absolute motion doesn't exist, but that isn't a justified conclusion; you're trying to justify it on the basis that absolute rest is the same as absolute inertial motion, and so we can conclude that absolute rest doesn't exist, and with it absolute motion; but we cannot conclude that absolute rest doesn't exist, because, for all we know the Earth could be at absolute rest.

    And even if absolute rest didn't exist, it would simply mean that no object in the universe is in a state of absolute rest, all objects are absolutely in motion. That doesn't mean we can't hypothesise about the possibility that an object could find itself at absolute rest - indeed, the Earth might just be at absolute rest - and use the mathematical construct for the purpose of deduction.

    In short, the idea that nothing in the universe is at absolute rest, and all things are absolutely in motion, but that it is, theoretically, possible for objects to be in a state of absolute rest, is closer to what is a justifiable conclusion from the experimental test of the principle of relativity, than the conclusion that absolute motion doesn't exist at all.

    I have corrected you on this before. It is, of course, true that the metaphysical assumption of absolute rest, and hence intrinsic motion, is consistent with relativity. It is also true that the contrary assumption, that no such metaphysical state exists, and that intrinsic motion is meaningless, is also consistent with relativity. Hence, relativity does not assume absolute rest or intrinsic motion.
    They are all supporting assumptions, and things we have to assume to be true, if we are to accept the kinematics of Einsteins hyperbolic geometry.

    I would agree that there are assumptions in Lorentzian relativity, for example the existence of a preferred, universal reference frame that determines the universal time. I do, however, believe that such an assumption can be removed from Lorentzian relativity simply by recognising that mathematical reference frames don't exist in reality, and that no object has to actually be at absolute rest; we only need to be able to speak about a hypothetical, imaginary absolute reference frame for the purpose of deduction, not for measurement. The need for an absolute reference frame, to define universal time, is further negated when we recognise the fact that time doesn't actually exist.

    Neither version of relativity supposes coordinate frames exist in Nature. Instead, the issue is the metaphysical assumption that all reference frames but one imply an observer who will be working with contracted/dilated instruments.
    As for the mysterious dynamics, I don't think they are any more mysterious than the idea of a hyberbolic geometry which gives the illusion of a mysterious dynamics, without actually affecting the dynamics; I just think the mysterious dynamics require us to make fewer assumptions that run contrary to our empirical experience of the world.

    They require far more assumptions. That is what Lorentzian relativity is missing, an underlying principle like hyperbolic geometry, producing relativistic kinematics. It instead has a wide variety of assumptions. Why, for example, does a bar of smoke contract by exactly the same amount as a bar of titatium, or a neutron star? Why do all the interactions conspire to behave the same way?
    I don't, however, believe that presentism is based on an assumption; I know that I have never experienced anything other than the present moment, and I think if everyone is being honest, then neither has anybody else.

    You might say that we have to assume that we share the same present, but I don't think this is accurate, because for it not to be the case every observer has to assume that their past continues to exist, and that their future already exists - this would run contrary to their empirical experience of the universe. In the absence of these assumptions about past and future, all we are left with is the present moment.

    Presentism is very much an assumption. The assertion that the present is all that exists is inconsistent with electromagnetism unless we assume some undetectable, metaphysical dynamical processes are under way.


  • #215
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    Morbert wrote: »
    I have corrected you on this before. It is, of course, true that the metaphysical assumption of absolute rest, and hence intrinsic motion, is consistent with relativity. It is also true that the contrary assumption, that no such metaphysical state exists, and that intrinsic motion is meaningless, is also consistent with relativity. Hence, relativity does not assume absolute rest or intrinsic motion.
    And I have addressed your corrections; the most recent reply in the absolute motion thread addresses these, so no need to go into them here.

    Morbert wrote: »
    Neither version of relativity supposes coordinate frames exist in Nature. Instead, the issue is the metaphysical assumption that all reference frames but one imply an observer who will be working with contracted/dilated instruments.
    Einsteinian relativity seems to suggest that relatively moving observers will observer mutual contractions, which arguably leads to a paradox - the subject of the other thread - but it also doesn't seem to account for how relative motion actually occurs; it requires the assumption of some mysterious dynamic which means worldlines which are static in spacetime, somehow give rise to the observation of relative motion.

    While absolute motion can easily account for a dilated clock, the issue of distance contraction is less straight forward, but perhaps not as damning as a theory about relativity, which doesn't account for how relative motion occurs.

    Morbert wrote: »
    They require far more assumptions. That is what Lorentzian relativity is missing, an underlying principle like hyperbolic geometry, producing relativistic kinematics. It instead has a wide variety of assumptions. Why, for example, does a bar of smoke contract by exactly the same amount as a bar of titatium, or a neutron star? Why do all the interactions conspire to behave the same way?
    You've mentioned the idea of a bar of smoke before, but I'm not entirely sure what you are picturing; how do you have a bar of smoke in absolute motion? Also, I don't see how you conclude that it requires far more assumptions; you seem to be stating different examples of the same assumption and claiming them to be different assumptions; particularly when the notion of hyperbolic geometry requires the raft of, aforementioned, supporting, assumptions.

    Also, as has been mentioned before, the idea that the hyperbolic geometry is, somehow, more than just spatial has yet to be demonstrated; without the underlying assumption about the physical nature of time, all you have is a spatial hyperbolic geometry, which conspires to give the illusion of the mysterious dynamics asserted in Lorentzian relativity; indeed, when we take gemoetry as what it is, a mathematical description of the matter in the universe, then Lorentzian relativity could be said to demonstrate a hyperbolic geometry as well, just not a 4-dimensional one, culminating in a eternalistic block, but a presentistic space.

    Morbert wrote: »
    Presentism is very much an assumption. The assertion that the present is all that exists is inconsistent with electromagnetism unless we assume some undetectable, metaphysical dynamical processes are under way.
    And it is only compatible with Einsteinian relativity is we assume that past and future exist eternally; that a clock measures the physical property of time; that clocks can tick both faster and slower than each other; among others.


  • #216
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    roosh wrote: »
    And I have addressed your corrections; the most recent reply in the absolute motion thread addresses these, so no need to go into them here.

    No you have not. You jump topics. Whenever we are close to wrapping up one of your misunderstandings, you introduce another. Whatever issues you might have with relativity, it does not imply intrinsic motion. This has been categorically demonstrated by myself. You can either address this, or we can move on to analysing the logical consistency and veracity of relativity itself.
    Einsteinian relativity seems to suggest that relatively moving observers will observer mutual contractions, which arguably leads to a paradox - the subject of the other thread - but it also doesn't seem to account for how relative motion actually occurs; it requires the assumption of some mysterious dynamic which means worldlines which are static in spacetime, somehow give rise to the observation of relative motion.

    While absolute motion can easily account for a dilated clock, the issue of distance contraction is less straight forward, but perhaps not as damning as a theory about relativity, which doesn't account for how relative motion occurs.

    You've mentioned the idea of a bar of smoke before, but I'm not entirely sure what you are picturing; how do you have a bar of smoke in absolute motion? Also, I don't see how you conclude that it requires far more assumptions; you seem to be stating different examples of the same assumption and claiming them to be different assumptions; particularly when the notion of hyperbolic geometry requires the raft of, aforementioned, supporting, assumptions.

    Also, as has been mentioned before, the idea that the hyperbolic geometry is, somehow, more than just spatial has yet to be demonstrated; without the underlying assumption about the physical nature of time, all you have is a spatial hyperbolic geometry, which conspires to give the illusion of the mysterious dynamics asserted in Lorentzian relativity; indeed, when we take gemoetry as what it is, a mathematical description of the matter in the universe, then Lorentzian relativity could be said to demonstrate a hyperbolic geometry as well, just not a 4-dimensional one, culminating in a eternalistic block, but a presentistic space.

    And it is only compatible with Einsteinian relativity is we assume that past and future exist eternally; that a clock measures the physical property of time; that clocks can tick both faster and slower than each other; among others.

    There are several issues with what you have said above. Your understanding of time in Einstein's relativity, for example, is still incorrect (an intrinsic, physical "time" is as meaningless as an intrinsic velocity in relativity). But, from your last post, it seems you now at least acknowledge that, however you might view relativity, presentism requires untestable assumptions about dynamics.


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  • #217
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    Morbert wrote: »
    No you have not. You jump topics. Whenever we are close to wrapping up one of your misunderstandings, you introduce another. Whatever issues you might have with relativity, it does not imply intrinsic motion. This has been categorically demonstrated by myself. You can either address this, or we can move on to analysing the logical consistency and veracity of relativity itself.
    I'm not sure where you think it has been categorically demonstrated, but if you want to highlight the particular point then I will re-read it, to see if there is anything that I have missed.

    The reason for the different threads is because we have been discussing different, but related topics; that they start to overlap is inevitable, but it serves the purpose of examining the issue from a number of different angles, and narrowing down the possible explanations. The conclusion we are closing in on is that, without implicit assumptions about absolute rest and motion, relativity only has one way of describing 3 physically distinguished scenarios.

    Morbert wrote: »
    There are several issues with what you have said above. Your understanding of time in Einstein's relativity, for example, is still incorrect (an intrinsic, physical "time" is as meaningless as an intrinsic velocity in relativity). But, from your last post, it seems you now at least acknowledge that, however you might view relativity, presentism requires untestable assumptions about dynamics.
    I'm not sure where I have given the impression of discussing anything other than the Einsteinian notion of time, with respect to Einsteinian relativity; but if you want to highlight the particular instances you are referring to, we can see if we can clarify the misunderstanding.

    Presentism itself doesn't require any assumptions about dynamics, it simply requires a lack of assumptions about past and future.


  • #218
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    roosh wrote: »
    I'm not sure where you think it has been categorically demonstrated, but if you want to highlight the particular point then I will re-read it, to see if there is anything that I have missed.

    The reason for the different threads is because we have been discussing different, but related topics; that they start to overlap is inevitable, but it serves the purpose of examining the issue from a number of different angles, and narrowing down the possible explanations. The conclusion we are closing in on is that, without implicit assumptions about absolute rest and motion, relativity only has one way of describing 3 physically distinguished scenarios.

    And when a particular angle has been investigated, you must acknowledge this. Instead, you change angles, only to come back to it when you figure it has been forgotten about.

    For example, we previously concluded that hyperbolic geometry reconciles the postulates of relativity with our intuitive understanding of how events are viewed from different perspective. See out "pole and centre of light sphere" discussion. Now, in another thread, you are drudging up the issue again, presumably forgetting what we have talked about before.
    I'm not sure where I have given the impression of discussing anything other than the Einsteinian notion of time, with respect to Einsteinian relativity; but if you want to highlight the particular instances you are referring to, we can see if we can clarify the misunderstanding.

    Presentism itself doesn't require any assumptions about dynamics, it simply requires a lack of assumptions about past and future.

    This is another issue we have dealt with before. Presentism, if it is to be considered consistent with electromagnetism, does require additional assumptions about dynamics.


  • #219
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    Morbert wrote: »
    And when a particular angle has been investigated, you must acknowledge this. Instead, you change angles, only to come back to it when you figure it has been forgotten about.

    For example, we previously concluded that hyperbolic geometry reconciles the postulates of relativity with our intuitive understanding of how events are viewed from different perspective. See out "pole and centre of light sphere" discussion. Now, in another thread, you are drudging up the issue again, presumably forgetting what we have talked about before.
    The error is in thinking that the issue was resolved; we didn't actually conclude that it resolves the issue, it's just that I couldn't see a way to proceed with the point.

    The point about the paradox of the clocks is a lot more straight forward.

    Morbert wrote: »
    This is another issue we have dealt with before. Presentism, if it is to be considered consistent with electromagnetism, does require additional assumptions about dynamics.
    Presentism on it's own doesn't require any assumptions, it is the absence of assumptions, and, apparently, self-evidently true - unless we make assumptions to the contrary.

    If we consider it with electromagnetism, then, assuming our understanding is complete, there are assumptions required about the dynamics of physical objects, not about presentism itself.

    If we consider electromagnetism in conjunciton with Einsteinian relativity, then we have to make a raft of assumptions about past and future, and the physicality of time, as well as assumptions about mysterious dynamics which cause static world tubes to give rise to the observation of relative motion.

    Would a form of emission theory resolve the issue of the mysterious dynamics by the way? I see that the De Sitter double star experiment is seen as a refutation of it, but it seems that it involves the simple addition of velocities, which appears to be erroneous.
    For an object moving directly towards (or away from) the observer at 9e3669d19b675bd57058fd4664205d2a.png metres per second, this light would then be expected to still be travelling at 5b1be7eb33dcabd1921c413ae3188698.png ( or 1e808aad9132c1e4c6a9ae9599a71dd6.png ) metres per second at the time it reached us.

    Willem de Sitter argued that if this was true, a star in a double-star system would usually have an orbit that caused it to have alternating approach and recession velocities, and light emitted from different parts of the orbital path would then travel towards us at different speeds. For a nearby star with a small orbital velocity (or whose orbital plane was almost perpendicular to our line of view) this might merely make the star's orbit seem erratic, but for a sufficient combination of orbital speed and distance (and inclination), the "fast" light given off during approach would be able to catch up with and even overtake "slow" light emitted earlier during a recessional part of the star's orbit, and the star would present an image that was scrambled and out of sequence.
    De Sitter - wiki



    The "brand" of emission theory it appears to deal with can be summed up as
    according to simple emission theory, light thrown off by an object should move at a speed of 4a8a08f09d37b73795649038408b5f33.png with respect to the emitting object


    As mentioned, that seems to involve a simple addition of velocities; if we consider the possibility that light travels at a speed c with respect to it's point of emission, as opposed to the moving emitter, then the idea that the "fast" light from a star, on it's approach phase, would overtake the "slow" light from the star, emitted while receding from us, would require the star to catch up to, and overtake, the light that was emitted while receding from the observer.


    It would still be an emission theory, it's just that the speed of light is relative to the point of emission, not the emitter.


  • #220
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    roosh wrote: »
    The error is in thinking that the issue was resolved; we didn't actually conclude that it resolves the issue, it's just that I couldn't see a way to proceed with the point.

    The point about the paradox of the clocks is a lot more straight forward.

    And the answer is still the same. Causality is preserved under Lorentz transformation. Two people disagreeing over which clock is ticking faster is no more a paradox than two people disagreeing over which radio sounds louder.
    Presentism on it's own doesn't require any assumptions, it is the absence of assumptions, and, apparently, self-evidently true - unless we make assumptions to the contrary.

    Yes it does. Inductive inference 101.
    If we consider it with electromagnetism, then, assuming our understanding is complete, there are assumptions required about the dynamics of physical objects, not about presentism itself.

    Hence, you are guilty of the very thing you are arguing against: Unphyscal assumptions
    If we consider electromagnetism in conjunciton with Einsteinian relativity, then we have to make a raft of assumptions about past and future, and the physicality of time, as well as assumptions about mysterious dynamics which cause static world tubes to give rise to the observation of relative motion.

    No we don't. The kinematics (not dynamics) are all very well described in any textbook, and not at all mysterious. They have a well established, rigorous, simple framework.
    Would a form of emission theory resolve the issue of the mysterious dynamics by the way? I see that the De Sitter double star experiment is seen as a refutation of it, but it seems that it involves the simple addition of velocities, which appears to be erroneous.

    De Sitter - wiki

    The "brand" of emission theory it appears to deal with can be summed up as

    As mentioned, that seems to involve a simple addition of velocities; if we consider the possibility that light travels at a speed c with respect to it's point of emission, as opposed to the moving emitter, then the idea that the "fast" light from a star, on it's approach phase, would overtake the "slow" light from the star, emitted while receding from us, would require the star to catch up to, and overtake, the light that was emitted while receding from the observer.

    It would still be an emission theory, it's just that the speed of light is relative to the point of emission, not the emitter.

    Emission theory has been throughly refuted

    http://en.wikipedia.org/wiki/Emission_theory

    If you assume light travels at a speed c with respect to the point of emission, rather than the emitter, then it would not account for MMX (and a variety of other experiments), unless you postulated mysterious dynamics, in which case you would just have Lorentzian relativity all over again.


  • #221
    Masteroid
    Closed Accounts Posts: 352 ✭✭Masteroid


    Morbert, do you regard 'time' as independent of the fundamental forces? Is the notion of 'time' not emergent from the interaction of energy/matter?


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  • #222
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    Masteroid wrote: »
    Morbert, do you regard 'time' as independent of the fundamental forces? Is the notion of 'time' not emergent from the interaction of energy/matter?

    Time, on its own, is an illusion, insofar is there does not exist some strict temporal metric or river of time. Instead, physicists talk of a "spacetime" metric that relates all events with each other. This spacetime also plays the role of the gravitational field. So time, as a facet of spacetime, is intimately related to the fundamental force of gravitation.


  • #223
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    Morbert wrote: »
    And the answer is still the same. Causality is preserved under Lorentz transformation. Two people disagreeing over which clock is ticking faster is no more a paradox than two people disagreeing over which radio sounds louder.
    The two examples aren't analogous, because time dilation isn't dependent on the proximity of an observer to the clock i.e. time doesn't slow down more the further an observer gets from the clock.

    The issue is that you are taking the general loudness of a radio, based on multiple tones emitted over a period of time; instead, it would be more analogous to say that a single note emitted from the radio can, all things being equal, exist at two different pitches. That of course would be a paradox.


    Morbert wrote: »
    Yes it does. Inductive inference 101.
    Every observer only ever experiences the present moment.

    If, as you contend, that the present moment isn't universally shared, it requires an assumption on behalf of every single observer, that both past and future exist.

    Presentism doesn't require such assumptions; it's the absence of them.

    Morbert wrote: »
    Hence, you are guilty of the very thing you are arguing against: Unphyscal assumptions
    It doesn't necessarily mean that the assumptions aren't phyiscal.


    Morbert wrote: »
    No we don't. The kinematics (not dynamics) are all very well described in any textbook, and not at all mysterious. They have a well established, rigorous, simple framework.
    Which assume that both past and future exist eternally, that a clock measures time, and that static 4-Dimensional world tubes can mysteriously manifest as relative motion.


    Morbert wrote: »
    Emission theory has been throughly refuted

    http://en.wikipedia.org/wiki/Emission_theory

    The refutation of emission theory appears to be on the basis of treating light as a projectile, like a bullet. The De-Stitter double star experiment suggests that light emitted from a star in it's approach phase could overtake light emitted during the regress stage; but that would require the star to first catch up to and then overtake the light that was emitted in the regress stage; if we take the simple addition of velocities, which we know doesn't apply to light.
    Morbert wrote: »
    If you assume light travels at a speed c with respect to the point of emission, rather than the emitter, then it would not account for MMX (and a variety of other experiments), unless you postulated mysterious dynamics, in which case you would just have Lorentzian relativity all over again.
    What mysterious dynamics would be needed?


  • #224
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    roosh wrote: »
    The two examples aren't analogous, because time dilation isn't dependent on the proximity of an observer to the clock i.e. time doesn't slow down more the further an observer gets from the clock.

    The issue is that you are taking the general loudness of a radio, based on multiple tones emitted over a period of time; instead, it would be more analogous to say that a single note emitted from the radio can, all things being equal, exist at two different pitches. That of course would be a paradox.

    Every observer only ever experiences the present moment.

    If, as you contend, that the present moment isn't universally shared, it requires an assumption on behalf of every single observer, that both past and future exist.

    Presentism doesn't require such assumptions; it's the absence of them.

    It doesn't necessarily mean that the assumptions aren't phyiscal.

    Which assume that both past and future exist eternally, that a clock measures time, and that static 4-Dimensional world tubes can mysteriously manifest as relative motion.

    The refutation of emission theory appears to be on the basis of treating light as a projectile, like a bullet. The De-Stitter double star experiment suggests that light emitted from a star in it's approach phase could overtake light emitted during the regress stage; but that would require the star to first catch up to and then overtake the light that was emitted in the regress stage; if we take the simple addition of velocities, which we know doesn't apply to light.

    What mysterious dynamics would be needed?

    These are the exact same arguments, but in different contexts, that you are making in the absolute motion thread here. The only new subject, which, no offence, is too silly to get into, is emission theory.

    Here's a a deal. When you first at least accept that a foundation of Einstein's relativity is the principle of general covariance, then we can move to other, competing theories.


  • #225
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    Light-cone structure
    A question which arises again from the statement about the light-cone structure is, how did my eight year old self remain eight years old; given that I was that 8yr old me, and I grew up to be the age that I am now? If it is simply a matter of light from that event not having reached a distant observer, then we can't really say that past and future exist eternally i.e. my 8yr old self doesn't continue to exist, just that a light signal from that event hasn't reached a certain part of the universe. This would preserve presentism, because that ligth signal would exist in my present moment, just in a different part of the universe, and any observer seeing it would effectively be seeing a photograph of the event, not the actual event itself.

    In order for the event to be preserved eternally i.e. for my 8yr old self to continue existing, the event must be physically extended, like a tube, in spacetime; but this just brings us back to the question in the other thread about how static world tubes give rise to relative motion.


    So, is it just a case of light from an event doesn't reach an observer in a distant part of the universe for a given length of time, or are objects physically extended, eternally, through spacetime; or is there something else at play there.


    Note: this isn't intended as a discussion on absolute motion, as that is being continued in the other thread, it is simply a question on the nature of light-cones and world tubes, which affect the discussion on the existence of past and present.


  • #226
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    roosh wrote: »
    Light-cone structure
    A question which arises again from the statement about the light-cone structure is, how did my eight year old self remain eight years old; given that I was that 8yr old me, and I grew up to be the age that I am now? If it is simply a matter of light from that event not having reached a distant observer, then we can't really say that past and future exist eternally i.e. my 8yr old self doesn't continue to exist, just that a light signal from that event hasn't reached a certain part of the universe. This would preserve presentism, because that ligth signal would exist in my present moment, just in a different part of the universe, and any observer seeing it would effectively be seeing a photograph of the event, not the actual event itself.

    In order for the event to be preserved eternally i.e. for my 8yr old self to continue existing, the event must be physically extended, like a tube, in spacetime; but this just brings us back to the question in the other thread about how static world tubes give rise to relative motion.


    So, is it just a case of light from an event doesn't reach an observer in a distant part of the universe for a given length of time, or are objects physically extended, eternally, through spacetime; or is there something else at play there.

    It isn't. We hear thunder later than when it happens. Similarly, we always see things after they happen. A framework does not define the present as "everything the observer sees at that moment".


  • #227
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    Morbert wrote: »
    It isn't. We hear thunder later than when it happens. Similarly, we always see things after they happen. A framework does not define the present as "everything the observer sees at that moment".
    It was an either or question; "it isn't" doesn't address it adequately.

    But, the above is precisely the point being made; just because a light signal from my 8th birthday party reaches a distant observer after I have grown up, and he "sees" my 8th birthday party, it doesn't mean that my 8yr old self continues to exist. Similarly, with the thunder example, the conditions which cause the sound waves to emanate outwards can change, while the sound wave exists in the present moment.


    But to return to the question; if I interpret what you meant correctly, are you suggesting that the light cone structure, which you say is what relativity says is physical - despite the statement that "objects exist as world tubes" - is not simply a case of light emanating from an event takes time to reach a distant observer? I presume this to be the case, because such an interpretation would not allow us to conclude that past and future co-exist with the present, in Minkowski spacetime.

    In order for my past,8yr old self, to co-exist with my present self, and for all moments in between to co-exist; then "I" must be physically extended through spacetime, "like a snake" or "tube" as you put it. Or world tubes must have some other form of mysterious manifestation.


    The question is, which is it?


  • #228
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    You are beginning to tread old ground again.
    roosh wrote:
    But, the above is precisely the point being made; just because a light signal from my 8th birthday party reaches a distant observer after I have grown up, and he "sees" my 8th birthday party, it doesn't mean that my 8yr old self continues to exist. Similarly, with the thunder example, the conditions which cause the sound waves to emanate outwards can change, while the sound wave exists in the present moment.

    Yes. But again, this is unrelated to the relativity of simultaneity.
    But to return to the question; if I interpret what you meant correctly, are you suggesting that the light cone structure, which you say is what relativity says is physical - despite the statement that "objects exist as world tubes" - is not simply a case of light emanating from an event takes time to reach a distant observer? I presume this to be the case, because such an interpretation would not allow us to conclude that past and future co-exist with the present, in Minkowski spacetime.

    In order for my past,8yr old self, to co-exist with my present self, and for all moments in between to co-exist; then "I" must be physically extended through spacetime, "like a snake" or "tube" as you put it. Or world tubes must have some other form of mysterious manifestation.


    The question is, which is it?

    The locus of all events that make up your history extend through spacetime as a world line.


  • #229
    Priori
    Closed Accounts Posts: 421 ✭✭Priori


    I am always suspicious of time being reduced, or explained in terms of, space. Both are fundamental forms of what Kant would call sensible intuition; the very things that make any experience possible. This includes the experience of physicists in a labratory.

    The human intellect cannot analyse time without 'fixing' it, representing it with lines and points (spatial concepts through and through). Time has already been abandoned when this is done.


  • #230
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    Priori wrote: »
    I am always suspicious of time being reduced, or explained in terms of, space. Both are fundamental forms of what Kant would call sensible intuition; the very things that make any experience possible. This includes the experience of physicists in a labratory.

    The human intellect cannot analyse time without 'fixing' it, representing it with lines and points (spatial concepts through and through). Time has already been abandoned when this is done.

    In mathematics, "space" has a rigorous definition that is more general than what a person typically means by space. For example, in classical mechanics, systems can be defined on a configuraton space. In quantum mechanics,a Hilbert space is used. Both of these spaces are distinct from a layman's understanding of space. Similarly, the Minkowski space of relativity is not the same as your usual space.

    So it isn't that time is reduced to "space". Instead, both "time" and "space" are understood to be facets of a deeper geometrical/chronometrical form. In the same way, relativity does not reduce electricity to a form of magnetism. Both electricity and magnetism are understood to be facets of a deeper form called electromagnetism.

    This is counter intuitive, but logically consistent.


  • #231
    Priori
    Closed Accounts Posts: 421 ✭✭Priori


    Morbert wrote:
    ...it isn't that time is reduced to "space". Instead, both "time" and "space" are understood to be facets of a deeper geometrical/chronometrical form.

    This is counter intuitive, but logically consistent.

    It's not that I find it counter intuitive at all. In fact I can see how it would have a large degree of intuitive appeal, particularly for those in a scientific discipline.

    A deeper geometrical/chronometrical form - just interested to know where you think time fits into this explanation?

    Chronometry refers to extremely accurate "clock time", if I'm not mistaken. And no matter how precise and sophisticated measurement becomes, clocks essentially treat time as if it were something extended (i.e. spatial) and divisible into discrete units.


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  • #232
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    Priori wrote: »
    It's not that I find it counter intuitive at all. In fact I can see how it would have a large degree of intuitive appeal, particularly for those in a scientific discipline.

    A deeper geometrical/chronometrical form - just interested to know where you think time fits into this explanation?

    Chronometry refers to extremely accurate "clock time", if I'm not mistaken. And no matter how precise and sophisticated measurement becomes, clocks essentially treat time as if it were something extended (i.e. spatial) and divisible into discrete units.

    My opinion would be the same as Hermann Minkowski's: Namely that time, on its own, isn't physical, and nor is space on its own. I think the salient word is not chrono-, or geo-, but rather metric. The relationship between events is codified in the Minkowski metric. The physicist Dirac, for example, used this simple form to predict the existence of anti-matter, before it has been detected by experiments. Field Theorists have used the form to predict the fine-structure of molecules with an accuracy of 1 in a billion, and the behaviour of electrons with an accuracy of 1 in a trillion.


  • #233
    Masteroid
    Closed Accounts Posts: 352 ✭✭Masteroid


    Priori wrote: »
    It's not that I find it counter intuitive at all. In fact I can see how it would have a large degree of intuitive appeal, particularly for those in a scientific discipline.

    What I find to be counter-intuitive is how we can have an expanding universe if spacetime is quantized.

    I mean, if the quantized particles of spacetime are moving away from each other all over the universe, that would explain expansion but what do we call the space between particles of spacetime? And doesn't this have implications for the constancy of the speed of light? How would a photon get from one piece of spacetime to another?

    It puts me in mind of stepping stones that are moving apart at a constant rate. The amount of energy that must be expended in order to reach the next stone increases on each step. There comes a point where you end up in the water because you simply don't have enough energy to make it to the next stone.

    If it were the case that photons did from time to time end up in non-spacetime space and so could pop up in any part of the universe at any time, shouldn't we be able detect some of them? Wouldn't they sometimes appear as a mysterious light source that just disappears? And wouldn't they distort the cosmic background radiation data?

    Also, it would seem a little disingenuous to claim that the planck-length is constantly increasing in real spacetime and that we just constantly call that increasing length 10^-33 cm or whatever it is.

    And if it were claimed that new spacetime was being constantly created within the constantly enlarging 'intersitial holes', so to speak, maintaining a contiguous arrangement of spacetime particles, then wouldn't that be in violation of the first law of thermodynamics?

    My head really hurts now. I must go and lie down.

    Mind you, if someone were to suggext that photons that are lost in non-spacetime space actually become a piece of new spacetime, I might sleep a bit easier.


  • #234
    Priori
    Closed Accounts Posts: 421 ✭✭Priori


    Masteroid wrote: »
    I mean, if the quantized particles of spacetime are moving away from each other all over the universe, that would explain expansion but what do we call the space between particles of spacetime?

    Reminds me of some of Zeno's paradoxes, which for the most part demonstrate the problems arising from infinite divisibility.
    Masteroid wrote:
    My head really hurts now. I must go and lie down.

    I know that feeling! :)


  • #235
    Shady93
    Closed Accounts Posts: 8 ✭Shady93


    Just discussed this in a lecture the last day! I cant remember who it was that said it, but the theory was that time can't exist. "Time" can be split up into three sections: past, present, and future. The past doesn't exist, because it is gone, only in our memories. The future doesn't exist, because it hasn't happened yet. But the argument is that the present can't exist either, because what is the present? It's a moment between the past and the future, but what's a moment? By the time you've focused on the moment, it's already whizzed by and become the past! Confusing stuff here :p


  • #236
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    Shady93 wrote: »
    Just discussed this in a lecture the last day! I cant remember who it was that said it, but the theory was that time can't exist. "Time" can be split up into three sections: past, present, and future. The past doesn't exist, because it is gone, only in our memories. The future doesn't exist, because it hasn't happened yet. But the argument is that the present can't exist either, because what is the present? It's a moment between the past and the future, but what's a moment? By the time you've focused on the moment, it's already whizzed by and become the past! Confusing stuff here :p
    According to Einsteinian relativity, however, past, present and future, all co-exist together in 4D-Spacetime.

    The present doesn't exist in the sense that there isn't a physical thing called "the present". If you stop for a moment and become aware of your experience; just resting in that experience, and being aware of sensations and thoughts, you are aware of "now".

    Assuming that the universe consists of more than just you, that means there are parts of the universe which are a distance from you - even the objects in the room you are in, are located a distance from you. But, resting in the "now" - without making any assumption as to the simultaneity of the objects you observer - and considering that the universe consists of more than just you, such that there are distant areas of space where things, or events, are happening, then you can reason that, as you are resting in that "now", there are events happening in distant areas of the universe which are simultaneous with that "now"; all of these things go to make up your present moment - even if you cannot determine what those distant events are (or were, at some point in the "future").


  • #237
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    Shady93 wrote: »
    Just discussed this in a lecture the last day! I cant remember who it was that said it, but the theory was that time can't exist. "Time" can be split up into three sections: past, present, and future. The past doesn't exist, because it is gone, only in our memories. The future doesn't exist, because it hasn't happened yet. But the argument is that the present can't exist either, because what is the present? It's a moment between the past and the future, but what's a moment? By the time you've focused on the moment, it's already whizzed by and become the past! Confusing stuff here :p

    There is also the relativity of simultaneity. What one person considers the present can consist of another person's past, present, and future.

    http://en.wikipedia.org/wiki/Relativity_of_simultaneity


  • #238
    krd
    Banned (with Prison Access) Posts: 3,455 ✭✭✭krd


    roosh wrote: »
    According to Einsteinian relativity, however, past, present and future, all co-exist together in 4D-Spacetime.

    Yes. But, if you were in the position of the Laplacian demon, where you had an absolute universal frame of reference, you'd see all the contractions and expansions.

    Humans can only, at the most, visualise 3 dimensional Euclidian space. Because we need to be able to percieve 3d spaces to survive. 4d spaces would be confusing. Euclidian transforms only work if the transform is instanteous. The second you bring time into it, Euclidian space breaks down. So, you need expanisions and contractions in space, relative to different obsevers, to get what we experience to work. As long as objects in different frames, with different velocities relative to each other do not interact - the objects experience no spacial or time distortions. When they do interact - the balancing experience is energy.


    If you move forward - and you consider yourself to be a wavefunction - a quantum object on two legs.....Relative to a "stationary" object, the front of your wave will contract. But relative to you, the wavefunction of the front of the object your approaching is contracted. If you collide, both your wavefunctions need to resolve the contraction, because now you're in the same frame. Either you and the object bounce off each other, and have new velocity vectors, or you travel together (which might give the illusion you're both at rest). Once you're at rest in the same frame, time and space distortions vanish - or appear to vanish. Elsewhere, from the position of another observer, your space is distorted.


  • #239
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    Just for the posterity of this thread, it is probably worth putting the following quote in here
    Morbert wrote: »
    The conclusion is the ontological existence or non-existence of an extended temporal dimension does not follow from the physical theory. The physical theory makes no ontological commitments. Hence, it cannot be used effectively to argue that time must exist or that time does not exist.

    So, Einsteinian relativity, and therefore relativity of simultaneity, cannot be used to effectively argue that time exists, because Einsteinian relativity doesn't make such ontological claims; it therefore cannot be used to argue that the universe isn't presentist.

    In the absence of such a counter argument, the lack of evidence for the co-existence of past and future, with the present, should lead us to the conclusion that only the present exists; in the absence of evidence to the contrary.


  • #240
    Masteroid
    Closed Accounts Posts: 352 ✭✭Masteroid


    roosh wrote: »
    Just for the posterity of this thread, it is probably worth putting the following quote in here



    So, Einsteinian relativity, and therefore relativity of simultaneity, cannot be used to effectively argue that time exists, because Einsteinian relativity doesn't make such ontological claims; it therefore cannot be used to argue that the universe isn't presentist.

    In the absence of such a counter argument, the lack of evidence for the co-existence of past and future, with the present, should lead us to the conclusion that only the present exists; in the absence of evidence to the contrary.

    But to be fair, the existence of only the present does not rule out the existence of time. We are still left 'With what causes change?' and time would be no less validated as the mediator of the change-force.

    If time doesn't exist, what is it that does?

    Could Special Relativity account for an alternative phenomena?

    I take the view that the effect of time is caused by the process of change rather than the other way around and the problem for physics lies partly, in my view, from trying to consider time as an essentially linear scale along which systems undergoing change 'mesh'. The linearity too, is an illusion.

    If the time variable's linearity were treated as varying with the constantly changing rates of rate of exchange of energy as they occur in systems being measured, then 'time' would more accurately reflect the thing it actually represents.

    That was a mouthful.

    In my view.


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  • #241
    roosh
    Registered Users, Registered Users 2 Posts: 2,554 ✭✭✭roosh


    Masteroid wrote: »
    But to be fair, the existence of only the present does not rule out the existence of time. We are still left 'With what causes change?' and time would be no less validated as the mediator of the change-force.

    If time doesn't exist, what is it that does?

    Could Special Relativity account for an alternative phenomena?

    I take the view that the effect of time is caused by the process of change rather than the other way around and the problem for physics lies partly, in my view, from trying to consider time as an essentially linear scale along which systems undergoing change 'mesh'. The linearity too, is an illusion.

    If the time variable's linearity were treated as varying with the constantly changing rates of rate of exchange of energy as they occur in systems being measured, then 'time' would more accurately reflect the thing it actually represents.

    That was a mouthful.

    In my view.
    What evidence have we got of times existence?

    Would the abundance of energy in the universe not cause systems to change, no?


This discussion has been closed.
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