Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Quantum causality

  1. Nov 21, 2013 #1
    I will bare in mind that causes may simply not be known today, however

    I would like to enquire about current non classic causality examples such as uncaused events; more specifically outcomes of experiments or matter to appear or change in an uncaused manner.
  2. jcsd
  3. Nov 21, 2013 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    Not exactly the clearest post in terms of what exactly it is that you mean by "uncaused". Are you aware of quantum fluctuation, quantum phase transition, and quantum critical points? Are those what you would categorize as "uncaused"?

  4. Nov 21, 2013 #3
    Thank you for your speedy response. I guess I do not know if "quantum phase transition, and quantum critical points?" are classifiable as uncaused I shall look up these subjects. I guess what I mean by uncaused is anything at all that occurs, appears or changes form that seems to have no cause...whatever those may be.

    I do know of quantum fluctuations however, in what way would you define these as having a-causal properties?
  5. Nov 21, 2013 #4


    Staff: Mentor

    As Zapper pointed out it's not quite clear what you mean by 'uncaused'.

    In QM the outcomes of observations cant be predicted, and this seems a general feature. When we throw a dice we know what 'caused' the random outcome. This is the sense QM is 'uncaused'. But it may also be a meaningless question in the sense nature may simply be like that - no cause required.

    As to explaining it there is a very deep theorem called Gleason's Theorem, that, assuming a basic aspect of the formalism of QM, implies nature at a fundamental level is like that:

    Also the modern view of QM is its basically one of the two most reasonable probability models that describe physical systems, the other one being the normal probabilities we encounter everyday such as weather forecasts saying there is a 20% chance of rain:

    I personally think nature is just like that - no cause required - but opinions vary.

  6. Nov 21, 2013 #5
    Thank you I will look into Gleason's_theorem .
    I agree with you, I feel that the universe on the macro scale is causal, but on the micro/quanta scale it is not, I know about quantum fluctuations and that they are with no cause and coming from nowhere, however I wanted more examples to broaden on what I know as being uncaused or a-causal in nature.
  7. Nov 21, 2013 #6
    I think the best you can say is that they appear to be non-causal. But how can we be sure that they really are? Consider that diffusion appeared to non causal until the theory of Brownian motion came long. Einstein was never happy with the dice model.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook