Plato’s weekend suggestions, episode 59

readingsHere it is, our regular Friday diet of suggested readings for the weekend:

‪The physics of past, present and future.

‪A strange article on science, post-truth, Thomas Kuhn, George Orwell, evolution and creationism…

Time management is ruining your life, seriously.

‪The future of the left: from detached irony to renewed seriousness?

A largely unelightening analogy between democracy and chess (soccer would have been better).

57 thoughts on “Plato’s weekend suggestions, episode 59”

  1. Alan White

    The Sudbery Time piece was interesting especially for its sweeping and clear presentation of the issues in historical context. My overall take is that his position from the internalist perspective is that of the “many-minds” variation of the more familiar externalist many-worlds interpretation of QT, but adopting a multi-varied or maybe fuzzy logic for his non-present future epistemology. That’s interesting, but he makes one claim that separates logic used in the present from logic used about the future (in his view). “Statements in the future tense do not obey the same logic as present-tense statements: they do not have to be either true or false.” I get that he means in part here that often present-tense logic is about present tense facts asserted true or false. But he says “the same logic”, which appears to mean that logic is bi-valent for the present, but muti-valent for the future. That’s an odd sort of duck. Why not adopt paraconsistent logic (maybe a fuzzy form of it to embrace the probabilities) for all temporal references, ala Graham Priest? Seems to me that would be compatible with his epistemological thesis and saves him from using two different kinds of logic for different kinds of times.

    I don’t endorse paraconsistent logic, but it might be better for his purposes than using two logics relative to times references.

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  3. SocraticGadfly

    Well, the Philadelphia angle is anti-democracy not post-democracy; but it’s on the line that we’ve probably never been as democratic, overall, as many people think from their high school history class.

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  4. synred

    In ‘many worlds’ interpretation reality is non-probabilistic. Which ‘world’ ‘you’ find ‘yourself’ in is still random, The numbers of worlds is absured. Every time an event occurs that creates an distinquialb branch (that can’t interfere with the other) a new world pops is created.

    All is determined but not for ‘you’. Doris is still right. Que Sera Sera.

    https://goo.gl/KEIxqj

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  6. synred

    I am uncertain about what will happen. Nothing fuzzy about that. It’s just plain true.

    What is ‘fuzzy logic’anyhow? It seems to me regular logic + probability pretty much covers the bases.

    I might rain tomorrow…If not quantitative there’s always the subjunctive

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  7. brodix

    The light cone for any event only comes together with its occurrence. For the future to be determined requires that “God’s eye view,” where all input is known before the event and that means information traveling faster than light. Now it can be argued all this energy is inertial and is going where it is going, therefore the future is determined, but what is involved to propose that total objectivity? For one thing, it is outside space and time, given the whole speed of light thingy, but that is as delusional as any intelligent design premise. How would we know outside space and time isn’t just a flatline? Also, can everything be known if it is infinite? Yes, the whole Big Bang universe as an object, but even the resident astronomer is a multiverse proponent. How can “everything” be known if t is infinite? It is an ideal and an ideal is a useful construct, nothing more. The future is probabilistic and only in our dreams is it anything but.

    “So if we fail to know the future, that is purely because we do not know enough about the present.”

    Ever hear the saying; “The more you know, the more you know you don’t know.”

    Only children and the naive think it can all be learned.

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  14. Robin Herbert

    I could write a program where I have dots moving around the screen according to a probabilistic rule then there would be a fact at any point in the program about what the next states will be (since my program uses a pseudo random number generator), so the probability of any given state being mext but an observer measuring the system will see things happen according to my probabilistic rule. So the system is deterministic but epistemically probabilistic (at least for any observer who cannot see the algorithm for the PRNG).

    If I substitute a real random number generator (if there is such a thing) then the system will be actually as well as epistemically probabilistic.

    But if I generated a huge database of every possible way the system could go and the observer is seeing one of these chosen at random and so it is back to the situation where there is a fact of the matter about the future of the system, it is actually deterministic but epistemically probabilistic.

    The last is my very loose analogy for trying to understand how probabilities pan out in many-worlds QM. That would work fine if my random number generator had a finite number of discrete outputs.

    If I could somehow generate that database using every point on the distribution then it would contain uncountably many paths and the paths in which the probabilistic rule was discernable would be no more frequent than those paths where it was not discernable.

    And, of those paths where the rule had been discernable to a certain point, the ones where it will be discernable after that point are no more frequent than the ones where the rule is undiscenable or unreliably discernable in the future. So if I were observing that system then I would have no basis for any prediction about the future.

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  15. synred

    The last is my very loose analogy for trying to understand how probabilities pan out in many-worlds QM. That would work fine if my random number generator had a finite number of discrete outputs

    That’s a pretty decent analalogy to ‘many worlds’. The problem as I see it is that the probablities don’t work out from the counting of worls. E.g., Suppose the state of election spin is

    psi==}+>/`/a

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  16. synred

    Trying again:

    Suppose the spin state of an electron is psi = |up>/sqrt(5)+|down>2/sqrt(5).

    When you measure the spin, two worlds are created – one with spin up and one with spin down. ‘You’ find a version of you self in each and thus if you repeat the experiment many times in each world ‘you’ will mostly find yourself in worlds where the up/down split is near 50/50. There will be ‘rare’ worlds where it differs a lot, but most of the you’s will be near 50/50.

    However, that does not produce the observed Born rule in which the ratio up to down would be 1/4.

    Various Oxford philosophers and some physicist have tried to explain this away. I haven’t seen one that doesn’t put the Born rule in by a hidden hand. In any case it’s not the simple counting one would expect from ‘many worlds’ interpretation. You can’t just crank the Schrodinger equation (including decoherence) and count.

    In Tegmark’s quantum suicide experiment worlds where you live would be common as hell as would experiments where you lived, but were severely injured. The worlds where you die would have a vastly larger amplitude, but there would be many were ‘you’ lived and many more where ‘you’ lived in agony.

    While in conventional QM interpretation (wave function collapse) these events are extremely unlikely to occur anywhere in our visible universe – so you can be pretty damned sure it won’t happen to you. If you shoot yourself in the head (accurately) you going to end up dead.

    If the universe is infinite as in current cosmological theory, it will happen some places, indeed an infinite number of places, but is unlikely to happen to you or me or anybody we could possibly know.

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  18. Robin Herbert

    I was reading about one of these ‘delayed choice’ experiments and it struck me that this is a potentially misleading way to describe it.

    As I understand the choice whether to measure, what to measure and when to measure is made after certain things have already happened, the idea being that the experimenters’ choices cannot, or ought not to be able to change what is already the case.

    It is potentially misleading because in several mainstream views of physics there is no actual delayed choice, only the delayed knowledge of what the experimenters will inevitably do. And there is no simple fact about what made these decisions inevitable and the others impossible. So how can they know the experimenters’ choices were indpendent of the thing they are testing?

    I know there is a view called ‘super determinism’ which says that they are not independent. But you can’t get any more deterministic than many worlds QM for example. So I wonder why thus view is not taken more seriously.

    It would not entail some massive conspiracy or improbable linkages, as some suggest. It would only require that there is, in fact, determinism

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  19. Robin Herbert

    Oh yes, Hogmany.

    I don’t drink any more and have probably slready derived as much enjoyment out of firework displays as I ever am, but a Happt Hogmany to all nevertheless.

    I shall have to see if I csn get a lump of coal yo you all, possibly by means of quantum tinnelling or a wormhole.

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  21. Robin Herbert

    That is one of the things I don’t understand about many worlds. Sometimes they talk in terms of the universe splitting but sometimes they talk as though there are never more universes, that you just find out something about the universe you are in, eg you find that you are in the universe where the particle is spin up and not the one where it is spin down

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  22. synred

    QM

    My favorite is Zeh’s ‘Strange His(tory) of QM’ which is linked on my QM page.

    Basically, decoherence due to interaction with environment causes the state to split into orthogonal states that can no longer interfere with each other and thus are in effect ‘separate worlds’ though still part of the same total quantum state.

    Zeh explains it better than I can.

    I don’t understand delayed choice experiments either.

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  23. synred

    do have a way to right a many worlds Monte Carlo. To get the Born rule to come out right I have to generate a lot of redundant ‘worlds’ to get the accounting to come close to Born rule.

    This makes for a very inefficient MC. In stead of ‘collapses’ states, I have to add extra ones so it’s at least as arbitrary as conventional Copenhagen tossing out all but one state. It is completely impractical as a simulation for any all but the simplest states.

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  24. brodix

    Isn’t part of the issue of the wave not collapsing is that it passes through the observer as well, rather than collapsing upon being observed? Then the wave is only disturbed to the extent it interacts with the observer.

    Don’t know if this is worded effectively, but it is that everything, including the observer, is part of the larger system. So the wave steers the observer, by creating the observation.

    So there are not multiple worlds, but only a completely relativistic one.

    ?

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  25. brodix

    When we propose complex thought experiments attached to this phenomena, it takes it out of context, adding effects, etc. that are not being accounted for in an otherwise self balancing system.

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  27. synred

    Hi Robin,

    https://en.wikipedia.org/wiki/Wheeler's_delayed_choice_experiment

    I”ve been reading about Delayed choice on wiki.

    It seems a bit silly. The same experiment would work with water waves and no retro-causality needed. If you open or close a second path interference pattern will appear even if the choice is delayed and will be replaced by dispersion (also a wave phenomenon) if it is kept closed. Nothing mystic about it.

    The mystery to me is how a spread out wave likes to interact only at one place. It seems like energy is mysteriously collects in one spot that was before the ‘collapse’, spread out. This is accounted for by decoherence [a].

    What I don’t understand is how the Born probability rule comes about. It appears as a kind of Deux ex Machina in the mind of Max Born.

    ]a] Here is my ‘entanglement interpretation’ which is pretty much equivalent to alternative histories which amounts to ‘many worlds’ with Born pruning. See https://goo.gl/z0l7rs

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