Ugh, the stupid “observe means observed by a conscious being” thing again. Any* quantum interaction will cause a collapse of the wave function. No conscious observer is required. When you do the experiment in a closed box and just increase the temperature to make it more likely for air molecules to interact with the laser you will also get a slit pattern.
*not really any interaction, scientists actually still aren’t sure what exactly constitutes a measurement, but we’re pretty sure a human is not needed
Would that also mean if a tree falls in the forest it always makes a sound because there’s always “someone” around to hear it? It sounds like we could say that the air or ground is “observing” the sound waves or impact made by the collision?
I think a tree falling is a little different from the double slit experiment, because the outcome of a tree falling will always be the same. That question is a little more philosophical about whether the pressurized air waves a falling tree makes are actually “sound” or whether it’s the interpretation of those waves done by our ears and brains that actually counts as “a sound”
The double slit experiment actually has two different outcomes, and that’s just some of that freaky quantum voodoo shit.
Yeah, the ambient temperature of the air should prevent the formation of a superposition afaik. And a tree would be too large to be in superporition in any likely scenario anyways.
Kind of, but I think that’s an altogether different question. The tree question is a philosophical one, basically asking whether sound is an objective element of reality or a subjective perception. The observer question is a scientific one, asking what conditions cause the interference pattern to collapse into two lines.
Not because there’s someone, but because it fell and caused the air to vibrate aka sound. Has nothing to do with “observing”.
I’m honestly sick of this rhetoric. “observing” for us humans requires a sense to be triggered, which most commonly would by our eyes and for that we need light. In quantum physics, that’s a problem, largely because even that tiny bit of light is a fucking nuke in this context. By the time it comes back to be picked up by the sensor, it has done its deed and changed everything. Similar issues with non light related ways of measuring.
This video has a lot more info, but she briefly mentions the experiment to further build on another popular myth. It’s such a refreshing channel to watch after all the quick pop science videos.
https://www.youtube.com/watch?v=RQv5CVELG3U
“Observe” in the double-slit experiment means placing detectors in each slit. Once you do that, the particles start acting as particles only. Without detectors you get the interference pattern. Doesn’t matter in either of the two setups if an actual human is looking at it or not.
Observer in this context doesn’t mean consciousness, but things such as detectors. If humans were replaced by robots and the robots did the same experiment, they would still see the interference pattern. It’s a common misconception that “observer” in the context of the double slit experiment means being observed by a conscious being.
Exactly. Or, you could just buy into “many worlds” and the idea that your brain and all the quantum particles that comprise it just join in on the laser beam’s wave function. (That’s an oversimplification but close enough)
Just like there’s no reason to believe the earth is at the center of the solar system, there’s no reason to believe that human consciousness is a fundamental part of quantum mechanics.
It’s been forever since I learned about this experiment in school. How TF did they measure the unobserved state, since measuring is an observation? Was it indirect measuring?
You don’t! You observe the result.
When no interaction happens the resulting pattern is described well with wave functions.
If interaction happens to determine which slit it is traveling through the double line result is seen and can be described by mechanical functions.
This “we have math for both results” for interpreted to “has properties of both wave and particle”.
Which I guess was one press release away from n"it’s both and depends on if I’m looking!"
The film on which the interference pattern is made is, in a sense, an observer. But the observer that most people mean is what was added after the wave-like interference pattern made researchers ask “okay, but which slit did the electron go through?” and they put a detector near the slits to determine an answer to that. When they did this, the wave function collapsed and the film no longer showed an interference pattern, but two bands, which would correspond to an particle-like electron going through either one slit or the other.
Basically the sensor is interacting with the quantum particle by measuring where it is before the slit. This collapses the wave function of the particle, causing it to appear at one point in space. Since the particle is collapsed to a point before the slit, it travels through only one of the slits and impacts the screen. Since it is just a single point particle now, there is no wave to interfere with the particle and create multi-line wave pattern, so we just see two straight lines on the screen that match up with the slits.
The sensor performing the measurement is the observer in this case. No living creature is needed to observe the particle to make it collapse. It’s simply just, quantum particles are just wave functions up until the point that they have to collapse to a particle because it has interacted with something (a screen or a sensor or anything). That is about the limit of my understanding at least
I’m not a physicist, so I’m unfamiliar with the particulars of how the detectors used work, but as I understand it, possible explanations like the one you suggest were initially considered as more likely than what was actually documented, but that’s where replicability helps out — if one research group observes something baffling that flies in the face of what is understood to be true, then maybe that’s an equipment or experimenter error. Not so much when a particular result has been demonstrated in countless different ways by many researchers, and when theories built to explain the weird stuff have predictive power for other, related phenomena.
Speaking of stuff that quantum mechanics helps us to understand, there are a few really cool examples of where quantum phenomena is relevant in my field of science (biochemistry), I’ll have a look to see if I can find the thing I’m thinking of.
Yes, that’s exactly what happens. Nobody has to check what it actually measured.
That’s what they did with the same experiment in a closed box where they just increased the temperature. In that case air molecules just acted as the “sensor” and collapsed the wave.
Agreed, but I’m still getting a vibe of that statement being correct at some level, from some point of view.
The nature of reality at the smallest scales is slippery, and it is still a fact that simply observing/interacting/measuring it has an effect, that layers of reality at their “pixel level” are blurry.
And it is absolutely astonishing that we as a species have developed the tools and know-how to reach this understanding.
Ugh, the stupid “observe means observed by a conscious being” thing again. Any* quantum interaction will cause a collapse of the wave function. No conscious observer is required. When you do the experiment in a closed box and just increase the temperature to make it more likely for air molecules to interact with the laser you will also get a slit pattern.
*not really any interaction, scientists actually still aren’t sure what exactly constitutes a measurement, but we’re pretty sure a human is not needed
“Observe means observed by a conscious being”
Can something without consciousness make an observation?
Yes, for example a photodiode can make an observation. Or a computer, or a photographic film.
That makes sense.
Would that also mean if a tree falls in the forest it always makes a sound because there’s always “someone” around to hear it? It sounds like we could say that the air or ground is “observing” the sound waves or impact made by the collision?
I think a tree falling is a little different from the double slit experiment, because the outcome of a tree falling will always be the same. That question is a little more philosophical about whether the pressurized air waves a falling tree makes are actually “sound” or whether it’s the interpretation of those waves done by our ears and brains that actually counts as “a sound”
The double slit experiment actually has two different outcomes, and that’s just some of that freaky quantum voodoo shit.
The tree could land in a different way though. Presumably until it’s observed it’s in all possible positions and rotations it could potentially be in.
Although presumably not because there’s always something observing it even if that thing isn’t self-aware and is in fact just a rock.
Yeah, the ambient temperature of the air should prevent the formation of a superposition afaik. And a tree would be too large to be in superporition in any likely scenario anyways.
Kind of, but I think that’s an altogether different question. The tree question is a philosophical one, basically asking whether sound is an objective element of reality or a subjective perception. The observer question is a scientific one, asking what conditions cause the interference pattern to collapse into two lines.
Not because there’s someone, but because it fell and caused the air to vibrate aka sound. Has nothing to do with “observing”.
I’m honestly sick of this rhetoric. “observing” for us humans requires a sense to be triggered, which most commonly would by our eyes and for that we need light. In quantum physics, that’s a problem, largely because even that tiny bit of light is a fucking nuke in this context. By the time it comes back to be picked up by the sensor, it has done its deed and changed everything. Similar issues with non light related ways of measuring.
This video has a lot more info, but she briefly mentions the experiment to further build on another popular myth. It’s such a refreshing channel to watch after all the quick pop science videos. https://www.youtube.com/watch?v=RQv5CVELG3U
Yes
“Observe” in the double-slit experiment means placing detectors in each slit. Once you do that, the particles start acting as particles only. Without detectors you get the interference pattern. Doesn’t matter in either of the two setups if an actual human is looking at it or not.
Observer in this context doesn’t mean consciousness, but things such as detectors. If humans were replaced by robots and the robots did the same experiment, they would still see the interference pattern. It’s a common misconception that “observer” in the context of the double slit experiment means being observed by a conscious being.
Does a camera have consciousness, or would the footage change after viewed by a human?
Exactly. Or, you could just buy into “many worlds” and the idea that your brain and all the quantum particles that comprise it just join in on the laser beam’s wave function. (That’s an oversimplification but close enough)
Just like there’s no reason to believe the earth is at the center of the solar system, there’s no reason to believe that human consciousness is a fundamental part of quantum mechanics.
It’s good to properly place our consciousness in the context of the rest of the universe and its physics. Still, it’s a great use of this meme format
It’s been forever since I learned about this experiment in school. How TF did they measure the unobserved state, since measuring is an observation? Was it indirect measuring?
You don’t! You observe the result. When no interaction happens the resulting pattern is described well with wave functions. If interaction happens to determine which slit it is traveling through the double line result is seen and can be described by mechanical functions.
This “we have math for both results” for interpreted to “has properties of both wave and particle”. Which I guess was one press release away from n"it’s both and depends on if I’m looking!"
The film on which the interference pattern is made is, in a sense, an observer. But the observer that most people mean is what was added after the wave-like interference pattern made researchers ask “okay, but which slit did the electron go through?” and they put a detector near the slits to determine an answer to that. When they did this, the wave function collapsed and the film no longer showed an interference pattern, but two bands, which would correspond to an particle-like electron going through either one slit or the other.
Could the whole thing be misconstrued, and just the proximity of the sensor be what is causing the wave collapse, not the observation?
Basically the sensor is interacting with the quantum particle by measuring where it is before the slit. This collapses the wave function of the particle, causing it to appear at one point in space. Since the particle is collapsed to a point before the slit, it travels through only one of the slits and impacts the screen. Since it is just a single point particle now, there is no wave to interfere with the particle and create multi-line wave pattern, so we just see two straight lines on the screen that match up with the slits.
The sensor performing the measurement is the observer in this case. No living creature is needed to observe the particle to make it collapse. It’s simply just, quantum particles are just wave functions up until the point that they have to collapse to a particle because it has interacted with something (a screen or a sensor or anything). That is about the limit of my understanding at least
I’m not a physicist, so I’m unfamiliar with the particulars of how the detectors used work, but as I understand it, possible explanations like the one you suggest were initially considered as more likely than what was actually documented, but that’s where replicability helps out — if one research group observes something baffling that flies in the face of what is understood to be true, then maybe that’s an equipment or experimenter error. Not so much when a particular result has been demonstrated in countless different ways by many researchers, and when theories built to explain the weird stuff have predictive power for other, related phenomena.
Speaking of stuff that quantum mechanics helps us to understand, there are a few really cool examples of where quantum phenomena is relevant in my field of science (biochemistry), I’ll have a look to see if I can find the thing I’m thinking of.
Oh yes, I suppose they could just place non measuring equipment near the slit and run the test again.
Yes, that’s exactly what happens. Nobody has to check what it actually measured.
That’s what they did with the same experiment in a closed box where they just increased the temperature. In that case air molecules just acted as the “sensor” and collapsed the wave.
Agreed, but I’m still getting a vibe of that statement being correct at some level, from some point of view.
The nature of reality at the smallest scales is slippery, and it is still a fact that simply observing/interacting/measuring it has an effect, that layers of reality at their “pixel level” are blurry.
And it is absolutely astonishing that we as a species have developed the tools and know-how to reach this understanding.
Correct. Whoever thinks that science kills the magic and wonders of life is an idiot. And that’s true for all the departments.
Relevant xkcd: