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Reality at what speed and what energy level

  1. Mar 19, 2006 #1
    When one attempts to understand REALITY it seems it eventually ends up connected to quantum mechanics. I do not think this is should be a factor when we are taking about a quark-based reality that exists at the temperatures, speeds and pressures found in the earth's biosphere where life exists. What happens at the core of the sun is a 'different' reality than what any human will ever experience. Likewise, what happens at the speed of light will never be experienced by any human. I agree that photons are very necessary components of our existence, but how photons behave has very little to do with the reality we experience at the very low velocity at which we exist. Anyone care to comment?
     
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  3. Mar 20, 2006 #2

    vanesch

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    Ah, you're touching upon one of my pet ideas :approve:

    I suppose that what you try to say, is: our physical theories suggest - if we take them seriously - that "reality" is totally different from what we feel in our bones to be reality - so how to deal with this apparent contradiction ?

    I've tried many times to point out that this is indeed a characteristic of the two main pillars of current physics: general relativity and quantum theory. For one reason or another, in the GR case, the tenet seems to be that the ontology presented by GR seems to be correct (never heard of "interpretational issues" with GR), although there is an obvious difficulty with this, which everybody seems to ignore - while quantum theory seems to have attracted all kinds of curses, leading to strange statements such as "quantum theory makes correct predictions, but doesn't describe reality".
    What's even worse is that these two theories are having serious difficulties being integrated in a united view.

    What are the two difficulties in GR and in QT ?
    In GR, the problem is "statism": the fact that spacetime "is". As such, time is just a coordinate, and as such, "yesterday" and "tomorrow" are existing on that spacetime manifold just as well as "today". But clearly, you only experience "today"! Yesterday seems to be "over" and not there anymore, while tomorrow is "not yet there". But that's not the picture that's presented to you by GR: yesterday and tomorrow are no different, physically, than today. Worse! Depending on how you look upon it, "tomorrow" could be, "far to the left" !
    Nevertheless, this obvious clash with our daily experience doesn't seem to have given rise to heated interpretational debates ; probably because the fourth coordinate is often written "t" and gives us a familiar feeling of the "t" which is running in the classical, Newtonian picture, and which indicates what is "today".

    On the other hand, in QT, all the curses have been falling upon its potential to say what reality is about. The thing that hurts, here, is of course the superposition principle, which says, grossly, that if quantum theory is to be applied to myself, I'm just as well still lying in my bed, as typing on PF, as being the minister of foreign affairs (ok, with relatively low amplitude) of the UK, as buying vegetables in the grocery store.
    While that's exactly what's said about an electron in a molecule...
    Such absurd nonsense has quickly been burried under statements like that this was a "formal tool" to "calculate outcomes of experiment", but should certainly NOT be taken as a description of reality.
    I'd like to point out that we've never done such a thing before with a scientific theory. We've never said that the theory of a round earth serves to calculate correctly the trajectories of airplanes and ships travelling to other continents, and even explaining the optical impression that satellites and astronautes get (they seem to see a spherical thing), but that, of course, the earth is "really" flat, and this spherical earth theory is not to be taken as a description of an underlying reality. It's just a formal tool... we've never done that !
    The attitude has always been, that if it walks like a duck, talks like a duck, then it IS a duck. But for QT, somehow, its presented ontology is so weird, that people prefer to make this strange statement that it is formally correct, but does not describe reality.

    So, how to handle this ? One way is to give priority to your "guts and bones" feelings, and to say that reality is what you've always known it was, and scientific theories, are, well, formal tools to help you calculate things, but who do not say anything about any reality ?

    The other way is to say two things: first of all, we do not KNOW for sure anything about reality, we only know about our subjective experience of it. And then, the role of a scientific theory is to present you with a description of reality, AND A RULE that tells you how to deduce, from that reality, a subjective experience. If that deduced subjective experience corresponds with what you do subjectively observe, then it is an acceptable statement - IMO - to say that this is a coherent view on "reality". This is the epistemological extention of the concept of empirical verification to the level of subjective experience.
    This seems to me to be a reasonable attitude, within the caveats which are two-fold: first of all, that all claims about reality, are ultimately no more than working hypotheses, and second, that scientific theories are falsifiable, and that the possibility exists that one day, the entire picture goes out of the window.

    As you might have understood, this last viewpoint is mine, but it contrasts with the view of many, who say that this view on, especially, quantum theory is simply too weird.
     
    Last edited: Mar 20, 2006
  4. Mar 23, 2006 #3
    Thanks for the great response. I have a couple of ideas on how to help integrate GR and quantum theory. GR may predict that a photon's trajectory may be altered as it passes by the sun, but it does not explain why. It is assumed that time is what a clock 'tells', but GR does not define what really 'is' or 'is not' space. Until one knows what one is curving, adding 3 dimensions of space to one dimension of time does not explain how a large collection of quarks affects the trajectory of a photon. GR tells nothing of the nature of the qraviton. IF Einstein had known that the graviton particle was what was curving spacetime, the last 25 years of his life might have been more productive.

    What do you think? Does it make sense?
     
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