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

B Questions about recent paper on Entangled Histories

  1. Jan 30, 2016 #1
    I just read this paper and it was very interesting. The paper is called "Experimental Test of Quantum Histories" http://arxiv.org/abs/1601.02943

    Here's some of an article about the paper.


    I have been reading a lot lateley about these Temporal Correlations and some Scientist are saying they are the foundation of reality that give rise to spacetime.

    The way I read it, is that there's correlation between events in time.

    I wanted to make sure I had this right. Are they saying that events in time are correlated so these events don't take any causual or sequencial order?

    To extrapilate this to a classical level, it would be like going to the store, Doctor and to a restaurant but all of these events occur essentially at the same time because there's no sequencial order of events. It ended this way.

    Last edited: Jan 30, 2016
  2. jcsd
  3. Jan 30, 2016 #2


    User Avatar
    Gold Member

    Is it better to have multiple chronologies all going forward, or a "single" chronology going forward and backward in time?
  4. Jan 30, 2016 #3


    User Avatar
    Science Advisor
    Gold Member

    You are correct. There are numerous quantum setups in which causal order is not classical. There is no single particular physical mechanism that can explain these setups. As a result, we have the interpretations. So your final conclusion will end up being interpretation dependent.

    The relatively newer class of experiments in which there is some type of delayed choice (as an example) are very difficult to explain outside of quantum theory itself. These had been predicted by QM but had not been executed. In these, it appears "as if" the future affects the past. Of course, just as with the "older" non-local quantum effects, there is no possibility of signalling.
  5. Jan 31, 2016 #4
    Thanks for the post and I found another recent article talking about this:


    I think this is very interesting and I have been reading up on these temporal correlations. They could be the foundation of everything. Events in spacetime might be entangled histories that only take on a sequencial order in spacetime. They talk about how you can encode information on these correlations that can only be read at a future time and it's like the information vanishes into the vacuum of these correlations until that specific time. It says:

    Some physicists take this as evidence for a profoundly nonintuitive worldview, in which quantum correlations are more fundamental than space-time, and space-time itself is somehow built up from correlations among events, in what might be called quantum relationalism.

    I think Scientist are scratching their heads because how do you explain these things in a physical context. It's the correlation of events in time with no causual or sequencial relationship. If you extrapilate this to spacetime, you would have all sorts of time travel and causual paradoxes. So the foundation of say me going to the store then going to the Doctor could be entangled histories on a quantum level that manifest as sequencial events on a classical level in spacetime. This would mean all events of the universe are correlated entangled histories that emerge as sequencial events in spacetime. Very good stuff and it would give new meaning to Einstein saying the distinction between the past, present and future is a persistent illusion.

    The universe could essentially be some kind of computer. Some Scientist say a quantum computer. This because these events that are entangled histories consist of bits of information. This information seems to exist in these entangled states without space or time. When space emerges, you get a sequencial order of events in spacetime. So the universe could simply be calculating this information and the universe as we experience it is the result.

    I also saw an interesting talk from John Preskill called "Is Spacetime a Quantum Error-Correcting Code?"

    Last edited: Jan 31, 2016
  6. Feb 2, 2016 #5
    Here's Physics Professor James Gates talking about finding error correcting codes in Superstring Equations.

    Here's a paper called "Quantum Gates and Quantum Circuits of Stock Portfolio"

    It's about a quantum code found in the stock market.



    So these temporal correlations or entanglement could the information that's being computed and our universe is the result. Spacetime is an error correcting code because the universe could constantly be computing itself and therefore updating itself. This should also mean errors occur because it's being copied so much and maybe we can detect those errors.
  7. Feb 2, 2016 #6
    What would Plank's constant represent in such a picture? Or c/h?
  8. Feb 2, 2016 #7
    In this scenario, Planck's Constant would be the refresh rate. In other words, it limits how much information the universe could process at the speed of light. Gizmado had an interesting article on this based on Quantum Realism called "10 Reasons Our Universe Might Actually Be Virtual Reality."


    M.I.T. Professor Seth Lloyd calculated this and said the universe has done 10^120 logical operations on 10^90 bits.

    Computational Capacity of the Universe
  9. Feb 10, 2016 #8
  10. Feb 10, 2016 #9
    Thanks for the article.

    I think there's growing evidence to support what M.I.T. Professor Seth Lloyd said years ago. He said the universe is a quantum computer. Maybe quantum mechanics isn't a physical theory but a computational theory and that's why there's a disconnect between classical physics and quantum mechanics.

    When you talk about things like entangled histories and temporal correlations it shows at the fundamental level of reality there isn't any physical cause and effect or a sequencial order. So we may not be talking about anything physical but information and computation. If you look at this website for instance, you see cause and effect. If I hit Quantum Physics on the main page the effect is I'm sent to the Quantum Physics board. So if you look at the website you see cause and effect but it's just following the instructions of the code.

    There was another recent study that showed there's no signaling between two entangled particles. This is just more evidence that what we call local realism is something that manifest on a classical level.

    When you look at no signals between entangled particle pairs, this is something that could point to the universe as a quantum computer.

    If you look at the spacetime as a computer screen and all of the matter in the universe as pixels on the screen, it's very easy to explain. I write code and let's say I write a program where red dots randomly move around the screen. If one of the red dots is clicked it turns blue or green. If two of the red dots touch each other then they're entangled. So now if I hit a red dot and it turns blue, the dot it's entangled with will turn green. If I click it and it turns green, the dot it's entangled with will turn blue.

    There's no need to send a signal between the dots because there just following the instructions of the program. So it's about processing information. So if the universe is governed by quantum codes, you wouldn't expect to see any signal between entangled pairs because both particles are pixels on the spacetime screen.
  11. Feb 11, 2016 #10
    Never thought of it like that! That's really interesting.
  12. Feb 11, 2016 #11
    Thanks and I write computer code and this explanation is just simple and elegant. There's growing support for this as well

    So if spacetime is a non local computer screen, you just need the code to tell the pixels on the screen how to behave and what laws to follow.
  13. Feb 11, 2016 #12
    Can't believe this. This is exactly what I have been contemplating for a while now! I can't get my thoughts around it (but I try)! Thanks for the references! :woot:

    NOTE: I like this one too (I call it: 'resonance'):
    Last edited: Feb 11, 2016
  14. Feb 11, 2016 #13


    User Avatar
    Gold Member

    Not only that but all possible outcomes can be encoded simultaneously with fewer degrees of freedom if there is a lot of entanglement.

    You have not mentioned ( I think) the holographic principle. Here's a sort of introduction but there are dozens of publications on this kind of thing



    Susskind, Leonard (1995). "The World as a Hologram". Journal of Mathematical Physics 36 (11): 6377–6396. arXiv:hep-th/9409089
  15. Feb 11, 2016 #14
    Would that mean that if we consider the universe as a whole, we then observe a single and definite outcome (evolution), because the entanglement is maximal?

    And a follow up question: in, for instance, the case of probabilistic QM (which is all of QM, probably), such as in the case of Alice and Bob measuring respective polarisations of entangled photons, would a measurement at t1 (one pair) and another at t2 (another pair) become entangled in the measurement setup in a whole different state of entanglement, and therefore depend on that state (of the measurement setup)?

    I pose the question here, because the topic suits the perfect context for it. :wink:
    Last edited: Feb 11, 2016
  16. Feb 11, 2016 #15
    Might the Heisenberg uncertainty have something to do with the limited amount of knowledge we are allowed to have, thus allowing for (the interpretation of) multiple histories that (must) remain unknown?

  17. Jun 1, 2016 #16
    I just came across this paper about entangled histories as well, and thought it better to continue in this thread rather than opening a new one.

    It seems that Wilczek says this experiment favors the many world's interpretation, but without having gone through the paper in detail, I'm guessing it doesn't formally have this meaning? I would like to ask the notable proponents for other interpretations on this forum if they have thought about what is done in this paper and why it would favor MWI. Also, are there other, just as natural interpretations of these results in the other interpretations, like BM?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted