God knows no better than Heisenberg

I have thought for many years that the point of Heisenberg’s uncertainty principle was that you could not measure a system without disturbing it. Hence the idea that your measurement of one aspect (say, momentum) must disturb another, like position, since all measurement involves interaction.

I was wrong. It turns out, at least according to John Barrow, that this is a vulgar misunderstanding of the Heisenberg principle, perpetrated as a way around the mathematical difficulties. What it in fact states is that the concepts of position and momentum stop making clear sense at a sufficiently small scale. So my clever idea that God might be the sort of entity (or fact about the universe) that could know without observing turns out to be as otiose as any other idea about God.

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7 Responses to God knows no better than Heisenberg

  1. Stephen says:

    The whole area is perhaps analogous to the problem of the boundaries in graphic images, when a large magnification is applied and it’s not clear where one element ends and another starts. Could it be that our whole existence is a collossal media presentation and that the limit is the boundary between one frame and the next. We only have the illusion of movement due to fast running frames. In that case we’re all like the character who comes out of the screen in Purple Rose of Cairo. Sorry this is not a very scientific comment. Just thinking aloud.

  2. Rupert says:

    There’s uncertainty, and then there’s quite remarkable certainty. I was reading last night about frequency comb lasers, which can be used to determine the frequency of light to a few parts in ten to the eighteen.

    That implies, I think, that we should be able to analyse the doppler from extremely distant galaxies well enough to determine their relative velocities to within a few centimetres a second, and can thus observe cosmological expansion as a first order phenomenon.

    It’s at times like this that I really have problems paying attention to theology.

  3. acb says:

    Oh, sure: it’s a very small scale at which we have to worry about these things. Did you know the value of the cosmological constant, which is what Einstein had to shove into his equations to make them agree with observation? It’s 10 -E -121. That’s a lot of noughts before you get anywhere.

    But I have to say I was hugely impressed with Barrow. He wasn’t trying to make a theological point. I was fooling around with that. He was trying to warn against vulgar, non-mathematical interpretations of Heisenberg.

  4. Some experiments appear to show that it is the looking at things that causes them to come into existence in a particular way. They can show that when photons are are left alone it can be found afterwards that one photon seems to have gone through two slots simultaneously and ended up at receptors on the other side. However if a gadget is placed such as to observe the photon going through both slots, it only goes through one of them. This theory leads on to a concept of infinite possible worlds out of which we sort of crystallize our own. However, that is another vulgar extrapolation from a problem with equipment. This is another angle on “if nobody sees anything does anything exist?” Somebody could argue if they wanted, that the photon going one way was like the famous tree that does or doesn’t make a sound when it falls in an empty forest. If somebody is watching/listening it does, if nobody is there then it both makes and doesn’t make a sound simultaneously. Then again, if nobody is there, who cares?

  5. On further thought, it might be that when something has no consequence it has no existence, doesn’t bother to exist. For all practical purposes you can assume that it was this way or that and it would be literally immaterial. (This is also the Schroedinger cat scenario, I think.) Maybe having a consequence is the definition of existence (try telling that to the cat, though), and the precise position of tiny particles is not usually of any consequence except when somebody wants to see it, and so never really exists as such, the particles never being in one precise position, until observed. Hawking ended his famous book with the conundrum of why the world “bothers to exist” is “because of us” or rather it is circularly “because it is” but without “us” there would be nothing but a sea of possibility.

    This can be hooked up nicely with the existentialism of “I do therefore I am”.

  6. Sorry, I think I meant:
    …why the world “bothers to exist”, maybe it is “because of us” or rather is it circularly “because it is”, but without “us” there would be nothing but a sea of possibility.

  7. acb says:

    Well, I don’t know. My instinct was that Barrow was trying to say something much narrower and more focussed than this. But I don’t ave the maths (see above). It seems clear enough that the concept of an “observer” in quantum mechanics is a lot more complicated than it appears at first sight to us, who are clearly observers of the wrong sort.

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