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Featured Is the PAST determined?

Discussion in 'Science and Religion' started by Polymath257, Aug 13, 2019 at 7:09 AM.

  1. Polymath257

    Polymath257 Think & Care
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    Many people like to ask whether the future is determined. This has relevance to issues like free will, for example.

    I would like to address the reverse question: Is the *past* determined?

    In other words, is the past fixed once we pass it?

    Another interpretation of the problem, possibly a different spin: Given the state of the universe *now* (and I am flexible about what this means), is the entirety of the past determined? Can every event of the past be *theoretically* deduced from the information of the present?

    When framed in this way, I have to say that it seems unlikely. For example, it seems quite unlikely that the weight of Casar's last drink is fixed from anything available in the universe today. It seems unlikely that the question 'was there a T-Rex standing in this spot 68 million years ago exactly' actually has an answer that is determined by the state of the universe now.

    So, to what extent is the past determined? If it is NOT determined, how does that affect your views of the past? if it *is* determined, in what sense is it so?
     
    #1 Polymath257, Aug 13, 2019 at 7:09 AM
    Last edited: Aug 13, 2019 at 12:16 PM
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  2. Rival

    Rival Noachide
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    I don't believe it is. I believe that what we call time is more complex and not linear as we see it.
     
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  3. Jim

    Jim Nets of Wonder

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    Unless and until it becomes possible to directly experience the past, the same times and places repeatedly, then all we can do is model it, without even understanding what it is that we’re modeling. Models are not true or false. They are only more or less useful, depending on how they are used and what they are used for. Another thing about models is that there might not be any single model that’s best for all purposes. Different models might be better for different purposes, like different kinds of map projections.

    I have considered the possibility that our memories actually are, partly and imperfectly, direct experience of the past.
     
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  4. Brickjectivity

    Brickjectivity Veteran Member
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    At relativistic speeds you and I could theoretically travel to the past and change the past of some far away galaxy though the journey would take thousands of years, however we could not travel to the Earth's past. This is not the same as saying our past is missing but the opposite. It evidences that our past is unchangeable by us.

    There is another limit to changing the past since we have learned of Entropy. If we assume that the universe is burning out slowly then someday it will no longer be possible for the past to change. That implies an end to change which propagates backwards to our time, a final, settled condition for space-time.
     
  5. 9-10ths_Penguin

    9-10ths_Penguin 1/10 Riboflavin
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    Seems like yes, the past is determined, but if you tried to deduce the exact state of things in the past from measurements of the state of things in the present, even if your measurement tools were perfect, you'd pretty quickly run up against fundamental limitations of the universe.

    As soon as you demand a precision for your measurements that's less than Planck length, you're asking more than the universe can provide.
     
  6. Polymath257

    Polymath257 Think & Care
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    So, if that is the case, in what sense is the past determined? Could there be more than one past consistent with the current state of the universe?
     
  7. Salvador

    Salvador RF's Swedenborgian

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    The block universe theory posits the past, present, and future exist simultaneously in a four dimensional block of space-time containing all the events that have and will ever happen as well as where the passing of time is an illusion.

    With the discovered link between space and time, they can no longer be thought of as two seperate things. Instead, space and time are fused together into what now is known as space-time. This fusion of space-time means the difference between past, present and future is only an illusion. Rather than thinking of time as continuous ,it's useful to think of time as a series of snapshots from moment to moment. If we conceptualize each moment or snapshot in our universe lined up one after another, we would see every moment that has ever happened or will ever happen, every location in space as well as each and every moment in time. Events I think of as happening now in various regions of space can be thought of as a now slice. When taking motion into account, I and somebody else could disagree with what exists on the now slice of time. A far away extraterrestrial being and I who are stationary relative to one another will share the same now time slice. When this distant extraterrestrial turns and starts moving away from me, he now would be in a new time slice that would be in the past from my prospective. When this distant extraterrestrial is moving towards me, he would now be in a new time slice that would be in the future from my prospective. Just as how we think of all of space is out there, the past, present, and future is out there now all existing together.

     
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  8. Altfish

    Altfish Well-Known Member

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    The problem is who writes the history books.
    In the US there are people trying to rewrite history.
    In the UK Brexit politicians are doing it everyday
     
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  9. Salvador

    Salvador RF's Swedenborgian

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    Reality might be able to be adjusted after events have occurred. this according to the results of the delayed-choice quantum-eraser experiment.


    [​IMG]


    Figure 1. Setup of the delayed-choice quantum-eraser experiment of Kim et al. Detector D0 is movable

    [​IMG]


    Figure 2. Simulated recordings of photons jointly detected between D0 and D1, D2, D3, D4(R01, R02, R03, R04)

    The experimental setup of the earliest performed DCQE involved an argon laser that shot 351.1 nm photons which went through a double-slit apparatus. After an individual photon went through one (or both) of the 2 slits, a Beta Barium Borate Crystal converted the photon into 2 identical entangled photons at half the original photon's frequency. The paths followed by each of the entangled photons were caused to become diverged by a Glan-Thompson Prism. One of these 702.2 nm photons (the signal photon) then traveled on a path from the Glan-Thompson Prism to a lens and then to a detector designated as D0. This point was scanned along its X-axis. A plot of the "signal photon counts" recorded at D0 versus X were examined to determine if the cumulative signal formed an interference pattern. The other entangled photon (the idler photon) went from the Glan-Thompson Prism to another prism where the idler photon was then deflected along a divergent path, depending upon which slit the photon went through. Beyond this path split, the idler photons encountered beam splitters that gave the idler photon a 50% chance of passing through and a 50% chance of being reflected by a mirror. The beam splitters and mirrors directed the idler photons towards detectors which were designated as D1,D2,D3 and D4. This experiment was setup so if an idler photon was recorded at D1 or D2, then this detected photon could have passed through either slit. If an idler photon were recorded at D3, then it must have passed through the one slit designated as Slit B. If an idler photon were recorded at D4, then it must have only passed though the one slit designated as Slit A. The optical pathway from slit to D1,D2,D3 and D4 was 2.5m longer than the pathway length from slit to D0. Thus, information acquired from an idler photon would occur 8ns later than information acquired from the corresponding entangled signal photon. The idler photon recorded at D3 or D4 provided a delayed "which-path" indication of whether the signal photon with which it was entangled had gone through Slit A or B. Whereas, the idler photon recorded at D1 or D2 provided a delayed indication that such "which-path" information was not available for its entangled signal photon. The experiment used a coincidence counter to isolate the entangled signal from photo-noise, recording only events where both signal and idler photons had been detected. ( after compensating for the 8ns delay ) When signal photons whose entangled idler photons were recorded at D1 or D2, the experimenters detected an interference pattern. When signal photons whose entangled idler photons were recorded at D3 or D4, the experimenters detected a simple diffraction patterns with no interference.

    Phys. Rev. Lett. 84, 1 (2000) - Delayed ``Choice'' Quantum Eraser

    Reference: Delayed “Choice” Quantum Eraser Yoon-Ho Kim, Rong Yu, Sergei P. Kulik, Yanhua Shih, and Marlan O. Scully Phys. Rev. Lett. 84, 1 – Published 3 January 2000 Issue
    Vol. 84, Iss. 1 — 3 January 2000


    The DCQE is unlike the classic double-slit experiment, in that the choice to preserve or obfuscate the which-path information of the idler photon was not done until 8ns after the position of its corresponding signal photon had already been measured at D0.

    Although, an idler photon was unobserved until after its corresponding entangled signal photon arrived at D0, interference at D0 was determined by whether a signal photon's entangled idler photon was recorded at D1 or D2 which was on a pathway where the photon's "which-path" information had been obfuscated, or at D3 or D4 which was on a pathway where the photon's "which-path" information was preserved.

    Does the DCQE indicate that the delayed choice to observe or not observe the idler photon's path affect the outcome of a past event?

    Does Relativity reveal that if quantum entanglement influences are able to travel faster than light, then they must also be able to travel backward in time and influence the past (which they do in this experiment)?

    I suppose that'd be all fine and dandy, so long as there'd be no immediately decode-able information transfer FTL into the past. So then, you couldn't go into the past and kill off your great great great grandparents, and create a paradox.

    Does the universe permit anything that doesn't make paradoxes, including FTL and backwards time travel of certain quantum influences (which are intertwined in relativity)?

    Perhaps you can reach back into time, so long as you preserve causality. Your changes would have to look like noise at the time, and could only have been seen to be otherwise when it's too late to make any difference (or light has had time to travel that far anyway, in the case of FTL)

     
    #9 Salvador, Aug 13, 2019 at 9:26 AM
    Last edited: Aug 13, 2019 at 9:41 AM
  10. Polymath257

    Polymath257 Think & Care
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    Sorry, but that isn't a correct interpretation of that experiment 9although it is a common misunderstanding of it). The problem comes from attempting to understand it with classical ideas. Under quantum mechanics, however, all the causality goes forward in time. The delayed choice only means that the wave function hasn't collapsed at that point because the measurement has not been finally resolved.

    But good try. :)
     
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  11. Terry Sampson

    Terry Sampson ζει

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    From the T.V. series "Fargo", third season, final episode:

    “Are you familiar with the Russian saying, ‘The past is unpredictable?’ Which of us can say with certainty what has occurred, actually occurred, and what is simply rumor, opinion, misinformation? We see what we believe, not the other way around.”
     
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  12. Brickjectivity

    Brickjectivity Veteran Member
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    The present and the past are too dissimilar in nature to make a correlation, like comparing the volume of the past to the area that is the present; however you might be able to make a correlation between all points in the past and all points in the future. Instead of determining the past from the present, you might try to determine it by using all time after this present moment. Computationally either approach is impossible but theoretically it makes no sense to try to compute all of the past just from all points in the present.
     
  13. shunyadragon

    shunyadragon Veteran Member
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    I agree with Einstein that the concept of past, present and future is an illusion. Our physical existence is determined based on the Laws of Nature, and we have to consider the past, present and future equally as to whether we consider them determined or not. The past present and future are subject ot the same Laws of Nature. Determinism does not translate to a mechanist rigidly predetermined existence. Single cause and effect events may be random, but the outcome of every event and the chain of cause and effect outcomes is subject to the limits of the Laws of Nature, The range of the possible outcome of cause and effect events is observed to be fractal based on the number of variables related to the event. For example; Weather is very variable and difficult to predict, because there are so many variables, but nonetheless prediction is possible prediction models are based on fractal math to model the possible outcomes of cause and effect events in weather.and based on fast and redundant computer programs.
     
  14. George-ananda

    George-ananda Advaita Vedanta and Spiritualist and Pantheist
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    Is the PAST determined?

    Are you familiar with the Mandela Effect discussed in the past on this forum? I am an experiencer of that effect and a believer in the effect.

    To blow our minds further, it is saying the past is not even consistent (like multiple valid versions).
     
  15. Earthtank

    Earthtank Member

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    "I would like to address the reverse question: Is the *past* determined?"

    Do you believe in time travel?
     
  16. Koldo

    Koldo Incredible Member

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    It looks up you are mixing up with three different questions together. Two are ontological questions ( "Is the past determined ?" and "Is the past determined by the present ?" ) and the third one is epistemological ( "Can we determine the past from the present ?" ).
     
  17. Polymath257

    Polymath257 Think & Care
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    fair enough. How do you see the differences? And what do you see the answers being for each?
     
  18. Polymath257

    Polymath257 Think & Care
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    No. Unless you think of our going into the future at the rate of 60 seconds every minute as time travel. :)
     
  19. Nimos

    Nimos Active Member

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    Maybe a thought experiment can help.

    (Now this is not to emulate reality)
    Imagine space completely empty besides two particles flying around. We know that at time X these are going to collide and the process of creating our Universe begins, so we are going to slow down time to the extreme. So as they collide 4 new particles are made and we know exactly how these behave based on physical laws and we keep doing this as we follow the Universe being created.

    Now would there at any point during the creation be a point where we would be surprised of how it developed, knowing exactly how all the particles etc. that is created are going to behave? So if we would never be surprised about how it developed could the past have been any different?

    The question is obviously if living being are so predictable as particles are?

    Besides that, we all live in the past :D Everything you see and react to are stuff in the past. For instance when you look at something, what you see is the light reflecting of something, which just haven't reached you eyes and been processed into useful information yet. Also to look at this in a greater scale, if the Sun were to explode, it would take approx. 8 minutes before we would notice it. So the pasts have already happened before we are even aware that it is the past, so I would say that it is determined unless I misunderstood what you meant :)
     
  20. Earthtank

    Earthtank Member

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    OK, well at least your answer proves you are somewhat sane. So, if we cant time travel to the past, then please explain, how you even logically or rationally ask the question of "is the *past* determined?" If you can NOT change an event then, yes, it has already been determined.
     
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