Schrödinger’s cat

This is a repost .

 

    Schrödinger’s cat is often used to illustrate the absurdity of quantum mechanics. Schrödinger devised the thought experiment to highlight the paradox implicit in the fact of entanglement. We are told that the cat is neither alive nor dead (or alternatively, that is both alive and dead) until we open the lid of the box, at which point the wave function describing the cat’s state is said to collapse into one or the other state.

     We are told that opening the box is an “observation”, and that it is the act of observation that causes the wave function to collapse. Opening the box kills the cat, or saves its life. Schrödinger devised this absurd thought experiment in order to clarify the paradoxes that appear to arise from entanglement.
     I understand entanglement as follows: two particles interact. They leave each other’s vicinity. The mathematics of quantum mechanics imply that until one of the particles is “observed” or “measured”, we cannot know which particle is in which state. However, when one of the particles is observed to have State S, the other will be in the complementary state S’. The usual interpretation is that until the measurement is done, the particles are in both states, which are said to be superposed on each other. The measurement forces the “collapse” of the indefinite state of the measured particle into one of the two possible states, and somehow this is communicated to the other particle, which collapses into the other state.
      Experiments have been done that show precisely this state of affairs. The question is whether the interpretation of the model is correct: Are the two particles actually in indefinite states until they are measured? Or is it merely the case that we cannot know which particle is in which state until we measure one of them? Note that measurement is an interaction. So the more accurate question is, Are particles that have interacted with each other in some indefinite state until their next interaction? Or is it the case that we cannot know anything about the state of either particle unless and until we arrange some interaction that results in effects large enough that we can both observe those effects and infer the state(s) that caused them?
     I think that QM is ultimately about the limits of knowledge, about what we can and cannot know about particles. Until we measure the particles, we can’t know what the result will be. More importantly, according to Heisenberg’s principle, the act of measuring the particles changes their states. However, measurement or observation is not a privileged interaction. It’s just one of many possible interactions, and it will be followed by another one, and then another one, and so on.
     As I understand it, the Copenhagen interpretation argues that the two particles are in superposed states until they are measured, at which point one of two possible states becomes real in some sense, and thus constrains the next interaction. The many-worlds interpretation argues that whenever the wave function collapses, both possible outcomes become real and ontologically separated from each other. I think both interpretations miss a fundamental point: QM, like any other theory, is a model. A model explains the data that have been observed. It can’t explain what isn’t part of the model. Interpreting QM ontologically or metaphysically is absurd.
     Schrodinger’s cat is alive or dead, as the case may, before we open the box. Our observation doesn’t cause cat to live or die: the radioactive atom that did or did not decay before we opened the box caused that. Suppose the wind blows open the lid. Then the wind is the “observer”, and either the cat’s corpse will stay in the box, or else the living cat will jump out and go on its way.

     In short: Human “observation” is not a privileged interaction.

           
    WEK 2013-11-18/2014-05-22
Update: New Scientist for 07 May 2014 has an article that expresses similar ideas.

Audrey Peterson. Elegy in a Country Graveyard (1990)

     Audrey Peterson. Elegy in a Country Graveyard (1990) Inoffensive fluff, involving a inheritance, a complicated backstory including an orphan musician genius and his governess, a baby-napping, an impostor, and a couple or three other nasties. The characters are pure cardboard, even the narrator barely suffices to carry the plot. And the plot, such as it is, is the only aspect with sufficient interest to keep you reading, albeit mildly bored. The crucial plot point, that a woman is not who she claims to be, is obvious almost as soon as she shows up, the rest is red herrings of an overbright hue, and all in all there isn’t much ‘teccing going on, despite the promise of “An Andrew Quentin and Jane Infield Mystery” on the cover. In other words, it’s a Harlequin Romance with pretensions to criminology, and as such is harmless enough fun. *½

Email encryption (link)

Came across this link to an email encryption system. Sounds good, but I think that the spooks don't need to know what's in the email. If you are a "person of interest", it's enough to know that you are using this service. And the path of the mail can be traced whether it's encrypted or not.

Amir D. Aczel. Why Science Does Not Disprove God (2014)

     Amir D. Aczel. Why Science Does Not Disprove God (2014) Aczel was annoyed by Dawkins “scientific atheism”, and decided to show that Dawkins failed to disprove the existence of God.
     This is a depressing book. The nonsense starts with the title, which is meaningless. You might as well say that science can’t disprove kittens. Of course not. Kittens just are; it’s what you want to say about kittens that can be proven. Or not, depending on what kind of thing you say.
     What Aczel is really trying to prove is that science cannot disprove that God exists. And that’s Aczel’s problem. If “God exists” is the same kind of claim as “Kittens exist”, then we want to know how he knows that. You can point to kittens, and say, “See, that’s what I mean by kittens”, and then you can spend some time agreeing or disagreeing that they’re kinda cute and all.
     But you can’t point to God. Any evidence for God is evidence if and only if you start with the assumption that God exists. In other words, “God exists” is an axiom. Aczel uses all the standard arguments to prove that God exists, but there is so much fuzzy thinking and slip-sliding from one definition or concept to another that it’s never quite clear what Aczel thinks he’s proving or disproving. His central point, that Science can’t disprove the existence of God is valid enough. But he doesn’t actually prove that claim, because he never states clearly what he means by “God exists”. Or what he means by “God”. He agrees that a “literal personal God”, such as the one in the Bible, doesn’t exist, but he doesn’t understand why that’s a valid theological stance. His theology is a muddled mess, and he shifts his grounds for disagreement with Dawkins from one chapter to the next, and often from one paragraph to the next. Worst of all, he doesn’t seem to realise that you can’t prove the existence of God either.
     He starts off by showing that much of the Bible narrative is corroborated by archeology. True. In fact it would be odd if that weren’t so, since all old historical texts are corroborated by archeology. But archeology also shows that much of the biblical narrative is at least exaggerated, and at worst simply wrong. In any case, the historicity of the Bible (or any other sacred text) proves nothing one way or the other about the existence of God.
     He spends a good deal of time arguing that Einstein, who explicitly rejected a personal god, really was religious. He makes the same claim about other scientists, and seems to believe that this supports the notion that a God of some kind exists. But the number of people who believe a proposition has nothing to do with its truth. The fact that other people agree with you doesn’t mean you’re right. And of course it's possible to be religious without holding a belief in a god.
     Much of the rest of the book is a mishmash of two arguments, the argument of the gaps, and the argument from ignorance. For example, he claims that “we” can’t account for the evolution of consciousness, art, symbolic languages, morality, and so on, so Something or Someone must have made it happen. We are different from all other animals. He doesn’t actually say so, but it seems he believes we humans have souls and other animals don’t.
     He accepts the Big Bang, but makes an elementary error: there must have been something before the Big Bang, he says. He even quotes St Augustine on the question, and misunderstands him utterly. Augustine’s point was that it’s meaningless to ask what there was “before” there was time. Aczel rejects the multiverse because the empirical implications appear to be untestable; but then he goes on to talk about those other universes as if they existed in our universe. I could go on, with his take on the improbability argument against the beginning of life; the inconceivability argument against the multiverse and string theory; and so on.
     Even at the end, Aczel still doesn’t explain what he means by “God”, even less what “God exists” might mean. He ends up with a vague pantheism, and pleads the inability of humans to understand everything about the universe as good grounds for accepting the “God hypothesis”. That phrase is itself telling. What Aczel really wants is scientific proof that God exists. He can’t have it, and if he did, he’d have to accept that God is just another phenomenon that can be studied scientifically. Is that really what he wants? I don’t know. He doesn’t seem to be aware that any proof of God’s existence makes that existence contingent. “God exists” would be a theorem, derived from some deeper axioms. What would these be? Or the proof is circular, such as the argument from design, which in effect says that design implies a designer, and therefore a designer implies a design.
     We humans have a strong urge to find or construct or impose meaning on our existence. This is I think a side effect of our ability to make sense of the world well enough that we can plan ahead and control our environment. We tell stories, because stories show cause and effect, and so both teach and comfort us. They teach us to devise actions that will make the story happen as we wish. And they comfort because they assure us that our lives have purpose. As in a story everything happens for a reason, so also in our lives. That’s what we want to believe, and most of us believe that without question.
     Does “God” exist? Tell me what you think “God” is, and I’ll tell you whether I think that god exists.
     This book will reinforce muddled thinking around the question and proves nothing one way or the other. Committed atheists will simple see just another badly reasoned attempt to refute their position. Muddled theists will take comfort that “science” can’t disprove their beliefs. *

Jericho: The Hollow Men (2005)

      The Hollow Men (2005) [D:Tom Shankland. Robert Lindsay, David Troughton et al] A courting couple dies by knife wounds, recalling a series of unsolved similar murders of 30 years earlier. A second murder puts pressure on Jericho and his team.  Personal problems, office politics, and family conflicts make their teamwork less effective than usual, but Det. Sgt. Harvey’s persistence in interviewing “John Bull”, a nutcase serial confessor, leads to the insight that breaks the case: “The murderer is someone like me”, says John Bull; he’s a traumatised WW1 vet. Det. Constable Caldicott almost becomes the murderer’s 6th victim, but Jericho and Harvey arrive soon enough to prevent that, and get Caldicott to his wedding on time. Another satisfyingly complex and nuanced episode. Jericho’s interrupted romance with Juliette, a French prostitute, begins again, so there’s hope this wounded warrior will find some healing. **½

Columbo: Double Exposure (1973)

      Columbo: Double Exposure (1973) [D: Richard Quine. Peter Falk, Robert Culp, et. Al] A motivational researcher, Dr Keppel, murders Norris, one of his clients, who’s about to fire him. He uses a subliminal cue, a single frame spliced into the draft  promotional movie, plus elevated heating, to trigger thirst, and runs a cassette tape, which enables him to shoot the victim at the drinking fountain while supposedly reading the script. He’s over-confident, of course, commits a second murder, and finally is trapped by Columbo’s use of subliminal stimuli.
      The story is nicely conceived puzzle, with enough character development to make us suspend disbelief of its more far-fetched notions, such as the precision of subliminal stimuli. The Columbo series enjoyed a deserved success, in large part because of Falk’s conception of the character. Columbo pretends to be puzzled, confused, and not very bright, which disarms the perpetrators. The narrative focus is on how Columbo solves the puzzle. The scripts are always well done, with good parts for the secondary characters, straightforward visual story telling, but occasionally intrusive music signalling some evil deed about to transpire.
     Like US movies generally, there is a surprisingly naive sense of evil. Evil spreads its effects like a stain and causes grief well beyond its immediate victims, but there’s almost zero awareness of that here. The victim’s wife is set up for a poor alibi, Dr Keppel’s projectionist is too willing to profit from Keppel’s crime, Norris’s business colleagues seem unaffected by his absence. Minor additions to the script or the acting would have added the hints of depth and wider context that would make this an outstanding series. As it is, it’s very good, and forty years later it still wears well. **½

Time

 Time
     Some thoughts prompted by an article in New Scientist (http://www.newscientist.com/article/mg22029410.900-saving-time-physics-killed-it-do-we-need-it-back.html)
     Apparently one of the unsolved problems in the Standard Model of physics is time. Time is not privileged: the arrow of time could run either way. The only obstacle to running time backwards appears to be probability, or the 2nd law of thermodynamics. It’s more or less improbable for a system to decrease its entropy; and local systems can decrease entropy only with the addition of energy, which is scavenged from outside the system and therefore increases entropy elsewhere. The overall entropy of the Universe is increasing: and that’s why the arrow of time runs forward.
     But time does not “emerge” from the fundamental laws of nature as now understood. Worse, there are paradoxes and inconsistencies.
     In relativity, time is tangled with space, and worse, there are no fixed, absolute times for events: the times, and hence the sequence of events, depends on who is observing what. That puts paid to the arrow of time in a thoroughgoing way. It’s true that for any given observer entropy increases in the expected direction. But the observed sequence of events will be different for two observers moving relative to each other. That implies that one observer will place an event in the past, and another in the future. And that causes problems.
     In quantum physics (if I get this right), the future is uncertain. Until there is an interaction, certain states of a particle are indeterminate. The technical term for this is superposition; and when the interaction that determines the state of the particle occurs, the wave function that describes it is said to collapse. But the wave function may also collapse randomly, with no apparent interaction. There is only a series of state changes, and it’s this series that determines the sequence of what we observe as events. This means that the future is fundamentally indeterminate. Worse, entanglement seems to delay events, such as acquiring spin. Couple this with relativity, and we get a paradox: the acquisition of spin will be determined from one point of view, and undetermined from another.
     The usual notion of time is that the past is fixed because it’s already happened, and the future is undetermined because it hasn’t happened yet. Both relativity and quantum physics undermine this notion. In both, time is a derived property. We experience time as a sequence of events, that is, a series of changes. In fact, we measure the passing of time by observing a series of events, such as the oscillations of a pendulum, or the burning of candle, or the vibrations of a quartz crystal.
     So what’s to be done to rescue the notion of time? Some physicists are working on tweaking the mathematics of the Standard Model in various ways so that time is an absolute, independent property of the Universe. As an outsider with only a metaphorical grasp of the Standard Model, I notice two things: First, in relativity, the observed difference in a sequence of events occurs only when those events are independent of each other. But when events are a causal sequence, such as the oscillations of a pendulum, it’s the intervals between events that varies for different observers, not the actual sequence. Second, in quantum physics, I notice a fixed sequence of events. Entangled particles may be in a superposed position until they interact with some other particle (such as the one placed in the path of one of them by the observer). Then their wave function collapses. But that wave function collapse always follows that interaction, it never precedes it. In other words, wave function collapse implies a temporal sequence, no matter how far apart. I also note that the random interactions that all particles undergo cause changes in state in fixed sequences. If an electron is in a given spin state, it may flip to the other. In fact, we know of spin states only because we have observed that sequence. So those observations that undermine the notion of time can occur only because we observe events in sequence, in time.
     Time is fundamental in some way that the Standard Model can’t account for. Either the Standard Model is the best we’ll ever do, in which case the mystery of time will never be solved; or else the Standard Model will be superseded. We do live in interesting times, don’t we?