Home > Uncategorized > The eeriest result I’ve seen in years

The eeriest result I’ve seen in years

Here’s a recent result posted online which, if it’s true, is incredibly eerie.

The upshot of it is that these guys claim to be able to have an experimental quantum entanglement setup that can affect events in the past. Not anywhere in the past, mind you, just specific, isolated events within the same experiment. Still, it’s an amazing result if someone manages to successfully duplicate it.

I rather suspect that they won’t succeed, and that the whole thing will turn out to be dodgy, but here’s the thing: if the result is correct, it probably invalidates the approach that I outlined in the last few weeks of posts. This is because, while the approach I outlined resolves problems with non-locality, it maintains a strict ordering of cause and effect.

I wanted to share with you because in digital physics, we like refutability! There are other discrete approaches in which this kind of result is probably fine, but my favorite model is probably toast.

I’d like to share with you what I think is wrong with this result, but first I should probably summarize the result, for those who don’t want to click around. It works like this:

* Alice and Bob both create pairs of entangled photons.

* One photon from each pair is sent to Victor.

* Alice and Bob make a measurement on their photons.

* Victor makes a decision as to whether to entangle the photons he received or not.

* When we check later, we find that whether Victor decides to entangle or not affects the correlation that Alice and Bob previously saw. Crazy!

So there are multiple reasons to suspect that this research requires more investigation before we know for sure. One is that each experimental pass seems to take place in 14 billionths of a second. That seems to me like a small enough window that experimental error could creep in. Another is that very few particles make it through the whole experimental setup, so the entire result hinges on statistical patterns in the collected data.

However, the thing that I wonder most about relates to the ordering of events. I haven’t gone through the paper yet but I suspect that the catch here is that Alice and Bob’s measurements are compared with Victor’s after Victor makes his decision.

Consider the case where Alice and Bob get to compare results before Victor makes up his mind. In that case, we have information with no quantum ambiguity traveling from the future into the past. My guess is they can’t do that. (If they can, financial trading will never look the same.)

And Victor has to decide first, the whole Alice/Bob/Victor setup only works if we treat it as an entangled system that we can’t touch until the whole trick is over. And that means we have to wonder whether Alice and Bob made a true measurement, if the outcome of it depends on whether we add Victor into the system or not.

In any case, it’s an awesome idea for an experiment. With luck, someone will be out there looking to repeat the result already.

  1. May 24, 2012 at 5:05 am

    No no no! For starters you should begin the post with something like “Another paradoxical result has emerged that is at odds with the so-called ‘continuous’ model of particle physics”. 🙂
    I don’t think it invalidates your previous model at all. As you pointed out in your previous posts, your model as it stands shows one feature (interference patterns) but will need to be extended to allow for others. It’s the same deal here. If you hold to the broad approach of a locally chaotic but large scaled euclidean network that evolves over time, there’s a huge range of different modelling extensions available that will still hold interference patterns.
    So how about this. Your model is locally spatially chaotic, but in the time dimension it is very uniform and linear. Changes occur globally in neat time steps. Why not allow local chaotic patterns in time? Perhaps the timesteps are not precisely synchronised across the entire network. Perhaps causality is chaotic too on small timescales. I’m sure a network algorithm could do that.
    Perhaps a short term entanglement event is a local geometic configuration in four dimensions that tends to occur as a byproduct of the network algorithm, and after the event, when you look at what happened, you can see there had to be a bit of very short term backward causality.
    At any rate, I think a discrete network has more possibility of explaining such a result than any continuous model does.

    • May 24, 2012 at 5:37 pm

      So you’re right. There’s nothing in this result that rules out a discrete approach. Indeed, some of the causal set based ideas I kicked around with Tommaso Bolognesi would handle this kind of thing just fine.
      The only thing that doesn’t work here, if the result is correct as presented, is the specific mechanism that I outlined in my posts, sans modification. In other words, a model that maps physical space onto a network and advances time in discrete, well-defined steps that are independent of any given subjective reference frame.
      One reason why I wanted to share the result was because of what I see as the importance of asserting refutability. I think it’s worth looking for experimental evidence that rules out one or more discrete models, even though those models are a very long way from being physical theories.
      I think this is important because at the moment, many of the reasons that physicists disregard discrete approaches are simply flat-out wrong. For instance, the belief that discrete systems are anisotropic, or unable to reconcile special relativity with QM, or unable to handle spatial curvature.
      By making clear statements about what different discrete models *actually* can or can’t do, we engage with the experimental process, however remotely.
      Having said all this, my favorite theory is still my favorite. I’m confident that time and space are *not* the same thing, and that cause and effect are well defined. I’ll be genuinely astonished if solid, repeatable evidence comes to light that this is not the case.

  2. May 25, 2012 at 10:06 am

    I think your “after Victor” comment is the key. it just looks like the Victor decision affected the Alice and Bob results. The whole system is closed until the final measurements are taken and compared. That’s the point that the quantum wave function collapses into a solution. So there’s no paradox, because you can’t actually change the decision Victor makes before he makes it, on the basis of Alice and Bob’s decisions.

    • May 25, 2012 at 5:09 pm

      Right. Even though Alice and Bob may look like they’ve made a measurement before Victor gets involved, what they actually have is a partial measurement of sorts. My guess is that you can only see whether the particle pair made it through the apparatus *after* Victor intervenes. Thus, those cases where Alice, Bob, and Victor’s actions yield a combination that doesn’t make for a nicely correlated quantum result, the particles tend to collapse elsewhere, yielding a ‘particle didn’t reach detector’ event instead.

  3. David Stewart Zink
    June 21, 2012 at 5:06 pm

    The whole FTL & time travel entanglement thing is worse than merely dodgy. You generally don’t even need “entangled” particles or any other highfaluting non-sense to reproduce the experiments.

    On the plus side, Science is merely “Logic” + “Causality”. If you can eliminate causality, then you have done away with Science. There is literally no reason to trust any scientific result, since they are all based on a false premise.

    Let’s entangle two billiard balls by painting one green and one red and putting them into separate boxes. Randomize the boxes and send one to the ISS. This is where frosh philosophy fits in: It is not true or assertable that the box at the ISS contains a red ball. It is not true or assertable that the box at the ISS contains a green ball. For the purposes of reasoning about what will happen after the box is opened, we say that it has a superposition of a red and a green ball, and then we can calculate consequences in two variations.

    Have the guy at the ISS open his box and immediately send you the video, and right before you are going to receive that video (but after he would have sent it) you open your box. You’ll find the other color! Amazingly, when he opened the box and “collapsed” the superposition of “red” and “green” to a single color, at FTL speeds the information was transmitted to YOUR box! Yay! You have discovered FTL communication.

    Similarly, there will be a way to reproduce the experiment you are responding to using ordinary household items and bad philosophy. Or else the results are completely faked.

    One usual way to fake this sort of experiment is to perform it often enough that the “chance of it happening at random” term is actually over 1/2. If you vary the experiment minutely each time, then obviously it wouldn’t have been exactly correct to combine the terms.

    • June 25, 2012 at 11:57 pm

      The point about boxes and balls is well taken. My friend Dan Miller has written some posts on this blog on this very subject.
      However, this kind of ball/box logic doesn’t let you get around Bell inequality violation. To do that, so far as I can tell, you need non-local passing of information in a very real sense.

      While I fundamentally agree with you about causality and its role in physics, I’m not ready to write this experiment off yet. It might not end up changing our opinions about time, but it might help refine our notion of what constitutes a measurement event in a quantum system.

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