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Was there quantum mechanics before it was discovered?

  1. Jan 8, 2013 #1
    According to quantum mechanic postulates, something which has not been observed does not exist(or at least, it's some kind of stochastic wavefunction but it's not determined). Now, we apply this to our physical laws. I guess the beginning of quantum theory was Planck's explanation of the spectrum of a black body. But does this means that before anyone measured the spectrum of a black body(or an aproximation because a black body doesnt exist of course) the spectrum wasn't defined so all of the laws derived from it also didn't exist. Does this mean that quantum physics only exists for slightly more than a century, since it didn't exist before it was observed? (Or just to be sure in case some ancient greek observed a phenomenon that can only be explained with QM, there was no quantum physics before planet earth existed) But if we look at distant galaxies, that light is already emitted long before earth existed. But still we can examine the spectrum of the light en determine of which elements they are made of, using theory of discrete energy levels in the atoms. Maybe there was some kind of entanglement which made the light behave in a quantum way before it arrived earth.
    Or if it's not entanglement someone else must have let the laws collapse in their known quantum way, so this prooves that aliens exist or have existed.

    But the problem is, if quantum physics didn't exist before they were observed, they also didn't exist during the big bang, and i believe the calculations of the beginning of the universe use quantum mechanics. So, they are wrong or somehow the collapse of the quantum laws when observed must have sent a signal back in time which made they have always existed.

    Ok, probably your first reaction is that I'm telling [censored brown smelly thing that comes out of the backside of a male cow], but what do you think of this thought experiment? And why am I wrong?
     
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  3. Jan 8, 2013 #2

    DrChinese

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    Welcome to PhysicsForums, thephystudent!

    Well, you are going a bit to far with this. There is nothing in QM that says the laws of physics didn't exist until they were discovered. There is nothing in QM that says it takes a conscious observer to cause wave function collapse. There is nothing in QM that says objects don't exist until observed. And this does not demonstrate that aliens exist.

    As far as there being some kind of something going backwards in time: There are interpretations of QM in which this idea is viable.
     
  4. Jan 9, 2013 #3

    Demystifier

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    But there is something in orthodox QM (and that something is called contextuality) which says that values of the observables don't exist until observed. So I think thephystudent asks good provocative questions addressed to those who accept such an orthodox view of QM.
     
  5. Jan 9, 2013 #4
    Isn't that just Copenhagen? A system is a superposition of everything at once, until you bring it in an eigenstate by observing it?(also like schrödingers Cat)
     
  6. Jan 18, 2013 #5

    Demystifier

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    A superposition is also an eigenstate of some observable. So being in a superposition is not the same as not having a value of an observable.
     
  7. Jan 19, 2013 #6
    "Does this mean that quantum physics only exists for slightly more than a century, since it didn't exist before it was observed?"

    The answer to that part is: no. Quantum mechanics existed before it was observed by us for sure. Such things as the formation of galaxies, and possibly the Big Bang itself, testify to existence of quantum mechanics a long long time ago (in galaxies far far away).
     
  8. Jan 19, 2013 #7

    bgq

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    Interesting questions!
    I have read that Schrodinger proposed his cat paradox to show that there is some issue with quantum mechanics. I think your questions do the same; however, quantum mechanics is our best until now (according to my knowledge) even though it could not explain everything in a way that is consistent with our innate logic (although consistent with respect to itself).
     
  9. Jan 19, 2013 #8
    Do you mean something along the lines of, are there phenomena that were not known to be of quantum nature until they could be looked at in hindsight using quantum mechanics? Or maybe, something was given an inaccurate classical explanations but was later more properly studied with quantum..?
     
  10. Jan 21, 2013 #9

    Demystifier

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    Strictly speaking, the fact that we see galaxies NOW is not the proof they existed in the PAST. It is logically possible that the light we see in the telescope was created at the very moment at which we have observed it.

    Of course, from the point of view of classical physics, such a view does not look very convincing. But the point is that such a view does make sense from the point of view of certain interpretations of quantum mechanics, especially those which try to avoid the conclusion that nature is non-local.
     
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