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Would life be meaningless if

  1. Dec 14, 2009 #1
    Hi, first of all, i am no physicist, but after doing some research on some physics theories i came to this question.

    If an infamous "law of everything" was discovered, and supposing we knew the state of the universe at a moment in time after the big bang, and also supposing that we had super mega powerful computers,¿Would it mean that calculating the outcome of all that to the present time or even beyond was already "destined" to be since the very beggining?

    I mean, if we had such law of everything and knew the state of the universe at any given point, we could calculate that in X planet called Earth, some molecules were going to generate primitive life forms that would evolve,etc,etc...and then all processes like the decisions of the living beings would be dictated by the same physics law, rendering such thing as conciousness as meaningless.

    I dont know if i made myself clear, but i tried the best i could.


    Sorry for any ortographical mistakes that there may be, english is not my native language.
  2. jcsd
  3. Dec 15, 2009 #2


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    In the olden days, this type of view was called determinism. Things like newton's laws and classical physics do work in precisely this way: if we know the state of the system at one time described completely by particles' velocities and positions, we can determine them at any past or future time.

    However, the idea of determinism was pretty much destroyed when quantum physics was discovered. This is manifested by the heisenberg uncertainty principle which states, for one, that we cannot know both the position and velocity of a particle with infinite precision at any given time; that is, there is always some inherent "fuzziness" in our measurements. Essentially, things become probabilities instead of deterministic trajectories.

    So in the framework of QM, no, there is no determinism because one cannot know the state of the universe to infinite accuracy at any given time. The best one can do is give probabilities (i.e this particle has a 90% chance of being found here in the next three minutes).

    It's a big subject and a lot of history and philosophy behind it, so you can read up more via google or wikipedia if you like, but that's essentially why determinism no longer exists.

  4. Dec 15, 2009 #3
    I would certainly argue that determinism is not dead. See http://plato.stanford.edu/entries/determinism-causal/#QuaMec for a philosophical overview of quantum mechanics' impact on determinism. The whole article is good if you're interested more, as is the related content linked at the bottom of the page.

    Cliff's Notes version:
    The fact is that no amount of science or observation can prove whether or not the world is deterministic. You can never prove that a probabilistic theory like QM doesn't have a more basic deterministic theory behind it. It seems to be an operating assumption of science, although not explicitly in most views of quantum mechanics, that the world is deterministic.

    http://philsci-archive.pitt.edu/view/subjects/determinism-indeterminism.html has a small sampling of some active research on determinism vs indeterminism. http://www.ucl.ac.uk/~uctytho/dfwIntroIndex.htm has a lot of good historical/introductory readings on the subject, although the editor has included his own views as well at the end.

    I definitely recommend reading that Stanford Encyclopedia of Philosophy page though.

    By the way, this question is outside the realm of physics. It can't be tested empirically for the reason given above. That's why we're giving you the philosophy angle, and that's also why quantum mechanics hasn't killed determinism :smile:.
    Last edited by a moderator: Apr 24, 2017
  5. Dec 15, 2009 #4
    As for the "would life be meaningless" part of your question, it seems like you are asking about the compatibility of free will and determinism. There is a debate in philosophy over whether or not the two are compatible. Compatibilism offers the view that the two are compatible, so you have nothing to worry about. See http://plato.stanford.edu/entries/compatibilism/. Incompatibilists argue that we can't have free will if determinism is true - but for the most part they also have reasons why you shouldn't worry about it :smile:. Actually, most incompatibilists argue that we also can't have free will if the world is probabilistic or random, and there are reasons for that too.

    Compatibilism, incompatibilism, and free will are other technical philosophical terms that you might want to look up. Again, the Stanford Encyclopedia of Philosophy is a great place to start for all of these.
  6. Dec 15, 2009 #5
    One other aspect is that, even if the universe is deterministic, it may not be possible to model its evolution on a supercomputer fast enough. You'd need a supercomputer that's bigger than your universe to do that.
  7. Dec 15, 2009 #6
    Isn't that the supercomputer that Douglas Adams posits in The Hitch Hiker's Guide to the Galaxy? The only computer large enough to pose the question about life, the universe and everything is ... the universe itself. (The answer to the question as expounded by the 2nd largest surpercomputer, Deep Thought, being, as we all know, 42. :rofl:)
  8. Dec 15, 2009 #7
    I don't think determinism or free will is related to whether the life of the living creatures have any meaning for the universe. We can assume that if we have free will this chance is bigger, but we could actually never know this for sure.
  9. Dec 15, 2009 #8
    As far as i remember, the uncertainity that involves quantum mecanics is simply a problem inherent to the current theories, not being able to resolve those problems.

    So, if we ever get to know a law of everything, even if we can't calculate the outcome of the universe because it is an immense task, it wouldn't mean that the universe isn't "deterministic".

    Anyways, is not like i would be sad or anything like that if that was true. The illusion of free will is so good that keeps me happy.
  10. Dec 15, 2009 #9
    +++Sorry for double posting+++
  11. Dec 15, 2009 #10


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    In my undergrad QM class, after we did all the formal mathematics and problem solving, we learned the same thing, and discussed a little bit about determinism.

    Ultimately, every science is deterministic in some sense. Otherwise it wouldn't be very useful to science (which generally makes predictions from quantitatively deterministic statements).

    This isn't an argument for a deterministic universe, just agreeing with kote that QM doesn't prove the universe is not deterministic.
    Last edited by a moderator: Apr 24, 2017
  12. Jan 17, 2010 #11
    I would like to respond, in my own way, to the idea that QM proves determinism false. Heisenberg uncertainty only states that definite positions and velocities are impossible to calculate, and thus for the purpose of calculations they must be represented as probabilities. However, the particle does have a definite position and velocity, and whatever that may be, it may or may not rely on a predetermined universe.

    And as for the philosophy of the matter of determinism, I have had similar thoughts. I found this quote from a close friend of mine useful and comforting:

    "Do what you will, as it may or may not be your will, but cherish those, and all, and everything you observe, for it could be in all your worth."
  13. Jan 18, 2010 #12


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    I believe the universe is deterministic regardless of the uncertainty principle. Since we need time in our equations, determinism better explains our universe. Although the universe is deterministic, a person would need a infinite amount of knowledge to predict the universe.

    As far as the theory of everything, the theory is impossible to construct because of Godel's theorem of incompleteness.
  14. Jan 18, 2010 #13


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    That is assuming the "hidden variables" interpretation of quantum mechanics which, in my opinion, has been pretty well discredited. A particle does NOT have a "definite position and velocity".

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