This has absolutely nothing to do with many worlds. Also, the article title is sensationalist, what a surprise.
This is yet another counter-intuitive but well understood manifestation of entanglement: one side interacts with something (in this case the cat stencil), the other side interacts with something else (in this case the screen), and the outcomes are correlated. The second splitting is a really neat trick, Anton Zeilinger is famous for performing ground-braking experiments in quantum mechanics. His work is always exquisite and can certainly be trusted. Some day this may have interesting applications, too:
One advantage of the technique is that the two photons need not be of the same energy, Zeilinger says, meaning that the light that touches the object can be of a different colour than the light that is detected. For example, a quantum imager could probe delicate biological samples by sending low-energy photons through them while building up the image using visible-range photons and a conventional camera.
But, again, one does not need to invoke many worlds to understand/explain what is going on here.
It’s not that I think many-worlds is ‘needed’ to explain it, just that whever likely-nonsense intuition I have over the subject is based on that model, so it’s best understood by me if it can be expressed in that frame.
Tell me it’s a photon that wasn’t there and I’ll go, “Whut?”
Tell me that the worlds cancel each other out to zero probability and I might, likely falsely, think I grok it.
But in this case? Not so bad. For the most part, the key is in part of TheMajor’s comment: “This blob can no longer interfere destructively with the blob that went through Path 2 (since they are now completely different when viewed in configuration space), so in particular the amplitudes for the yellow photon no longer cancel out.”
That’s something that the QM sequence covers, is easy to understand with MWI, and the grokkage can potentially be as close to cromulent as non-technical understanding of QM gets.
The one thing that I’d add is that if the yellow photons do cancel out on the camera, then it’s not like they don’t exist, or the branches of the wavefunction cancelled out completely—just, when the interference happened, the photons end up somewhere else, not on the camera. If you don’t get that, then yeah, that grok was utterly false.
However, I think that having MWI in mind would help you avoid that error, since one of the main ideas is that worlds are never destroyed. Negative interference just indicates where a world didn’t go.
I think that having MWI in mind would help you avoid that error, since one of the main ideas is that worlds are never destroyed. Negative interference just indicates where a world didn’t go.
Right. Would be good to have a visualization from the MWI point of view of what you and TheMajor wrote up.
Weeeelll… when I visualize MWI it’s just the same as my visualizing the math of QM itself. I’m not sure how someone who doesn’t know the math would visualize it. Presumably, using EY’s configuration-space-blobs, like TheMajor used in his description.
Those aren’t great for predicting the outcome of interference since you have to tack on the phase information, but they are very good for noticing when things aren’t going to interfere at all.
This has absolutely nothing to do with many worlds. Also, the article title is sensationalist, what a surprise.
This is yet another counter-intuitive but well understood manifestation of entanglement: one side interacts with something (in this case the cat stencil), the other side interacts with something else (in this case the screen), and the outcomes are correlated. The second splitting is a really neat trick, Anton Zeilinger is famous for performing ground-braking experiments in quantum mechanics. His work is always exquisite and can certainly be trusted. Some day this may have interesting applications, too:
But, again, one does not need to invoke many worlds to understand/explain what is going on here.
It’s not that I think many-worlds is ‘needed’ to explain it, just that whever likely-nonsense intuition I have over the subject is based on that model, so it’s best understood by me if it can be expressed in that frame.
Tell me it’s a photon that wasn’t there and I’ll go, “Whut?”
Tell me that the worlds cancel each other out to zero probability and I might, likely falsely, think I grok it.
Likely falsely, yes.
… because quantum mechanics is hard in general.
But in this case? Not so bad. For the most part, the key is in part of TheMajor’s comment: “This blob can no longer interfere destructively with the blob that went through Path 2 (since they are now completely different when viewed in configuration space), so in particular the amplitudes for the yellow photon no longer cancel out.”
That’s something that the QM sequence covers, is easy to understand with MWI, and the grokkage can potentially be as close to cromulent as non-technical understanding of QM gets.
The one thing that I’d add is that if the yellow photons do cancel out on the camera, then it’s not like they don’t exist, or the branches of the wavefunction cancelled out completely—just, when the interference happened, the photons end up somewhere else, not on the camera. If you don’t get that, then yeah, that grok was utterly false.
However, I think that having MWI in mind would help you avoid that error, since one of the main ideas is that worlds are never destroyed. Negative interference just indicates where a world didn’t go.
Right. Would be good to have a visualization from the MWI point of view of what you and TheMajor wrote up.
Weeeelll… when I visualize MWI it’s just the same as my visualizing the math of QM itself. I’m not sure how someone who doesn’t know the math would visualize it. Presumably, using EY’s configuration-space-blobs, like TheMajor used in his description.
Those aren’t great for predicting the outcome of interference since you have to tack on the phase information, but they are very good for noticing when things aren’t going to interfere at all.