Good question to ask, since specifics of selection process may affect the decision outcome! Other variants include growing humans in a vat from scratch on demand, using Star Trek transporter clones, or abducting the necessary number of people from a pre-selected list where your name happens to be the first one. For now, imagine the potential population as the 5 billion living cognizant adults.
as X approaches infinity, the difference becomes negligible
It may be negligible to the 4.999… billion adults sleeping comfortably and securely in their beds tonight, but the problem presupposed that you have already been abducted. It remains underdefined whether you refers to you the specific person reading this meme, or a more general you-the-unfortunate who has been chosen and is now listening to this on the headphones.
I want to clarify that the “cannot” here refers not to the inadequacy of our tools (which hypothetically could have been fixed in the future by building better tools), but by a fundamental prohibition of the quantum mechanics theory. Practically, the single-photon lasers and detectors used here are like 90%+ efficient - plenty good enough to distinguish between the two monkey scenarios. But some observables in quantum mechanics are “orthogonal” - you can measure one or the other, but not both at the same time - the math will not allow it. The typical example of that is “position” and “momentum” of a particle.
The math is quite beautiful actually, the analogy I’d use is something like asking “Which way is east at the North Pole?” In your head you can either know “This direction is east.” or “I am standing at the North Pole.” but you cannot hold both pieces of knowledge in your head at the same time.
The orthogonal observables in this experiment are the “which-way top/bottom slit” information and the “which-interference-category Pattern 4/Pattern 5” information. It’s even more beautiful in the delayed choice quantum eraser experiment that I was ranting about here. There, both pieces of information are stored orthogonally in a single photon. You can choose at a later time to either measure it one way, which will tell you the which-way info, or in a different way, which will tell you the interference category info, but there is no hypothetical way to measure it in both. The only way you can get the category info out to allow your computer to draw the interference pattern is if you guarantee that the which-way information has been irrecoverably erased. It is as if the whole universe conspires to censor this information from you! But it’s just the consequence of the math rules in use.
There was some scare in lemmy development circles recently about script injection vulnerabilities. The various apps and frontend developers “solved” the problem by peppering untrusted user input with escape sequences all over the place. User submits post? Escape title! Receive new post from a federated instance? Escape title!
Obviously if you escape the title twice and display once, it will show up weird. The problem is that the various devs haven’t agreed yet which parts of the messaging protocol are supposed to be already escaped and which are not. Ideally all user input should be stored and transmitted in raw form, and only escaped right before displaying. But due to various zealously-cautious devs we get this instead:
They talk about how it was never actually possible to do this before, because it requires very fine “electron optics” and manufacturing of components, like slits and shutters, with nanometer precision. So while the thought experiment with electrons itself was proposed by Feynman in 1963 (which is probably what inspired the monkey meme and the like), it was not actually realized until 2019. I’m also now guessing that the electron quantum eraser paper from 2014 doesn’t use a double slit but some other electronic quantum circuit that is easier to work with.
The two-stripe photo to match the monkey meme, with electrons and measuring which-way information, probably doesn’t exist yet. So that’s why!
Yes, double slit interference happens with both photons and electrons, and even with C60 buckyballs and organic fluorescent dye molecules (arxiv.org/abs/1402.1867)! This post is more so about the quantum eraser, as a counterpoint to the 12 posts about it that @kromem wrote in the other thread. The first experimental quantum eraser paper from 2001 uses photons, so that’s the figures I used here. There might be newer papers that use electrons, like this one doi.org/10.1126/science.1248459 from 2014, but I don’t have access to it. I presume detecting the electron there using induced current or whatever would disturb its wavefunction to the same severity as using the polarizer filter does here.
In this experiment, yes. There could be other experiments with electrons instead of light, maybe where you toggle on some kind of magnet to measure which slit an electron goes through, but the measurement itself would still disturb the electrons in a manner where you shouldn’t be surprised when the interference pattern disappears.
I mean, quantum mechanics is still definitely different from classical physics. There are things like the quantum bomb tester, and the Bell inequality violation is still totally real. But the way quantum mechanics has been presented to me in popular science has totally fucked me up. It was not until college quantum physics classes that it all turned out to be actually quite straightforward. And every each time after that when I go back to a research paper underlying some popular science presentation I’ve seen in the past, it turns out there was some giant 3d glasses just off-screen that the presenter somehow “forgot” to mention, and awareness of whose presence totally removes the “fuck”-factor.
In this experiment, they didn’t even bother measuring which slit each photon passes through. The 3D glasses don’t measure or observe the photons, they merely polarize them (although they do block 50% of light). The detector D_S doesn’t measure which-path information either. The researchers could have placed a circular polarizer in front of D_S, and when they get a hit they could have said with confidence “this photon came through the top slit!” but they didn’t even bother doing it this time. The fact that the 3D glasses alter the light in a manner which makes the which-path information theoretically measurable (even if not actually measured), alone is sufficient to destroy the interference pattern.
Both this paper and the delayed choice quantum eraser experiment paper (arXiv:quant-ph/9903047) only show a single blob, not the double stripe. If anyone has a paper that clearly shows a photo with the double stripes the way it’s shown in the classic monkey meme, I’d like to add it to my collection!
Obviously if the slits are big and wide enough apart you will just get two spotlights, so that doesn’t count. It wouldn’t even demonstrate wave physics, let alone quantum. It has to be a paper where there is some switch you turn on or some filter you slide in place or whatever that makes the image on the physical screen toggle between two stripes and multiple.
If we cover one slit, it will look like figure 3, shifted to the side and at half intensity.
The paper doesn’t use an actual screen, they only have the detector D_S that they move up and down to record the coincidences. I simulated what the monkey would see had there been a screen in place for the purpose of the meme. I copied down the datapoints from the graph and simulated 100,000 photons hitting the screen with the probabilities indicated by those points. My javascript pastie is available here: html.cafe/xcd2a5ed3?k=19f51bff26c65bcf253ee5257a5… Importantly, the monkey can never see images 4 and 5 on the physical screen - those can only be displayed on the computer. The monkey will only ever see image 3, which is the sum of 4 and 5.