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Oh god no. That video is very misleading and pretty much borders on pseudo-science. For starters it depicts photons as balls, when it would be much less confus

Oh god no. That video is very misleading and pretty much borders on pseudo-science. For starters it depicts photons as balls, when it would be much less confusing and more intuitive to instead think of them as waves with discreet energy amounts. If you think about it as a wave, what's happening is a wave with a photon-amount of energy passes through both slits which causes an interference pattern. When it hits the wall it coalesces into a single particle/dot. Also, it talks about 'observer' and strongly indicates the observer needs to be a conscious entity. Instead of observer, just use the word "detector", and bear in mind that detector interacts with the photon (whereas at the classical level you can watch or observe something without affecting the system).

alberth 4y ago
Would you mind linking to a better video, suitable for a general audience. The difficulty is most video are either way to technical or way too high-level.
- jjbinx007 4y ago
  I recommend videos by Arvin Ash. He's one of the few who manages to explain things in a way that makes sense to me. A lot of Youtube videos either parrot the pop-sci explanations I get tired of reading in magazines or they're way above my head.
criddell 4y ago
The video talks about shooting electrons rather than photons through the slits. Does it matter what kind of particle you shoot through? If I fired a stream of hydrogen atoms or neutrons through the slit, would I get an interference pattern? I’ve also always wondered if it matters what side of the slits the detector is on? The experiment as depicted in that video has the detector on the gun side of the slits. Would you get the same thing if you moved it to the wall side of the slits? Also, does the wall itself count as a detector/observer?
- PeterisP 4y ago
  The effect applies to all particles, but it does matter what kind of particle you shoot because the sizes involved become very different. Apparently, the effect has been demonstrated even with molecules of 2000-ish atoms - https://www.nature.com/articles/s41567-019-0663-9 https://www.nature.com/articles/s41567-019-0663-9
- lmm 4y ago
  > Does it matter what kind of particle you shoot through? If I fired a stream of hydrogen atoms or neutrons through the slit, would I get an interference pattern? Everything has a de Broglie wavelength, but the more massive it is the shorter the wavelength, so you'd need closer slits and higher-resolution detectors to notice anything. I guess if you used a really big particle then you'd reach a point where it would be bigger than its own wavelength and you couldn't observe any wave behaviour. > I’ve also always wondered if it matters what side of the slits the detector is on? No, the important thing is observing which path it takes > Also, does the wall itself count as a detector/observer? Not unless there's a way for you to tell when and where it hits the wall.
zmgsabst 4y ago
A small point: A finitely bounded wave is better described as a wavelet. https://en.wikipedia.org/wiki/Wavelet https://en.wikipedia.org/wiki/Wavelet Particles are the wavelets that when summed, give us the field as a whole, ie, particles are the wavelet transform of a field.
Lerc 4y ago
I'm not sure if detector is any better than observer. Isn't it the issue of when does it collapse/decide (also problematic terms) rather than the multiple options propagating into the detector? Observer get used because at least then someone is experiencing the decision. Many worlds punts on that option by making a new observer world each way. I'm a layperson who reads a bit so I could be misinterpreting. I was always partial to the idea of probabilistic squeezing rather than collapse. In the absence of quantum gravity, probabilities can propagate only as far as their gravitational effects allow. As particles interact the compatible possible positions reduces to eventually squeeze the location to an infinitesimal size. It may be utterly wrong as an idea but it would negate the need for observers, detectors, or many worlds which makes it a bit compelling.

alberth 4y ago

Would you mind linking to a better video, suitable for a general audience. The difficulty is most video are either way to technical or way too high-level.

jjbinx007 4y ago
I recommend videos by Arvin Ash. He's one of the few who manages to explain things in a way that makes sense to me. A lot of Youtube videos either parrot the pop-sci explanations I get tired of reading in magazines or they're way above my head.

criddell 4y ago

The video talks about shooting electrons rather than photons through the slits. Does it matter what kind of particle you shoot through? If I fired a stream of hydrogen atoms or neutrons through the slit, would I get an interference pattern? I’ve also always wondered if it matters what side of the slits the detector is on? The experiment as depicted in that video has the detector on the gun side of the slits. Would you get the same thing if you moved it to the wall side of the slits? Also, does the wall itself count as a detector/observer?

PeterisP 4y ago
The effect applies to all particles, but it does matter what kind of particle you shoot because the sizes involved become very different. Apparently, the effect has been demonstrated even with molecules of 2000-ish atoms - https://www.nature.com/articles/s41567-019-0663-9 https://www.nature.com/articles/s41567-019-0663-9
lmm 4y ago
> Does it matter what kind of particle you shoot through? If I fired a stream of hydrogen atoms or neutrons through the slit, would I get an interference pattern? Everything has a de Broglie wavelength, but the more massive it is the shorter the wavelength, so you'd need closer slits and higher-resolution detectors to notice anything. I guess if you used a really big particle then you'd reach a point where it would be bigger than its own wavelength and you couldn't observe any wave behaviour. > I’ve also always wondered if it matters what side of the slits the detector is on? No, the important thing is observing which path it takes > Also, does the wall itself count as a detector/observer? Not unless there's a way for you to tell when and where it hits the wall.

zmgsabst 4y ago

A small point: A finitely bounded wave is better described as a wavelet. https://en.wikipedia.org/wiki/Wavelet https://en.wikipedia.org/wiki/Wavelet Particles are the wavelets that when summed, give us the field as a whole, ie, particles are the wavelet transform of a field.

Lerc 4y ago

I'm not sure if detector is any better than observer. Isn't it the issue of when does it collapse/decide (also problematic terms) rather than the multiple options propagating into the detector? Observer get used because at least then someone is experiencing the decision. Many worlds punts on that option by making a new observer world each way. I'm a layperson who reads a bit so I could be misinterpreting. I was always partial to the idea of probabilistic squeezing rather than collapse. In the absence of quantum gravity, probabilities can propagate only as far as their gravitational effects allow. As particles interact the compatible possible positions reduces to eventually squeeze the location to an infinitesimal size. It may be utterly wrong as an idea but it would negate the need for observers, detectors, or many worlds which makes it a bit compelling.