gonna keep banging this drum every time this comes up:
When physicists say “observe”, they actually mean “measure”. And to measure a photon of light, you have to interact with it somehow, there is no passive way to do so.
The post’s header image implies that the interference pattern goes away just by looking at it. If that were the case, we would never see the interference pattern, never know it was there in the first place! In the actual experiment, they put a sensor at one or both of the slits. But to “sense” a single photon, you have to interact with it in some way. Otherwise you wouldn’t know it was there.
Again, this is where the language trips us up. Rather than “sensor”, would really be more accurate to say they put a photon-touch-er at the slits.
So, what we actually get is “Touching the photon changes the photon’s behavior.” The universe doesn’t magically infer when we happen to be looking at it, there is no spooky action-at-a-distance!
kruhmaster@sh.itjust.works
on 10 Sep 20:08
nextcollapse
Alrighty then, but don't say that I did not warn you:
...
...
...
Yes. Except after I peeked, it no longer exists. But the people - THOSE PEOPLE - they, haha, they hehe they claim that I am the ones who are (sic) crazy, the absolute fools! They refuse to know what I have seen!!
It’s funny until you meet someone who actually believes that human eyes change quantum results
idiomaddict@lemmy.world
on 10 Sep 13:59
nextcollapse
It’s a reasonable thing to think from the way it was described in my physics class, at least. I fault people a lot less for misunderstanding something that even scientists in the field don’t really understand than for something like thinking the earth is flat.
chocosoldier@lemmy.blahaj.zone
on 10 Sep 14:08
nextcollapse
i fault them for doubling and tripling down when corrected, with sources, because they’d rather keep believing a fantastic lie.
spankinspinach@sh.itjust.works
on 10 Sep 18:48
collapse
In fairness, there was a whole Journey song about it
They don’t even explain it in physics class. That is kind of the schtick of the Copenhagen interpretation. You just assume as a postulate that systems are in classical states when you look at them and in quantum states when you do not, and from those two assumptions you can prove using Gleason’s theorem that the only possible way the former can map onto the latter is through the Born rule. But there is no explanation given at all as to how or when or by what mechanism this transition actually takes place.
Many Worlds isn’t much better because they posit that the classical world does not even exist, yet that clearly contradicts with what we directly observe in experiments, so if that is true it necessarily means that the classical world is an illusion, and so then you still have to explain how the illusion comes about, which they do not. Dropping the postulate that there is indeed a classical world also disallows you from deriving the Born rule through Gleason’s theorem, and so it then becomes unclear how to do it at all without some arbitrary additional postulate, and the arbitrary nature of it means there are dozens of proposals of different postulates and no way to decide between them.
Modern physics is of the form (1) there is a quantum state, (2) you look at it, (3) a miracle happens, (4) you perceive a classical state, and then you are repeatedly gaslit into believing quantum mechanics is a complete theory of nature and it’s impossible for there to ever be anything more fundamental than it and any physicist who thinks there might be, even if they are literally Albert Einstein, is a crank crackpot. They then take on the same playbook as the Christians where when you point out their explanation seems to be logically incoherent, they say, “God has no obligation to make sense to you” as an excuse to be incoherent and making no sense, but just replace “God” with “nature” and the same argument is repeated verbatim.
GreatTitEnthusiast@mander.xyz
on 10 Sep 17:37
collapse
The book The Quantum Magician makes this mistake
The protagonist has a quantum brain and to use it they have to turn off their consciousness in order to not collapse the superposition. I face palmed whenever they mentioned it
Anyone actually know what measurment devices are used to observe which slit the electron passes through? How do we know that a specific measuring tool isn’t changing the experiment significantly enough to cause issues with outcome and that the behavior change is abnormal?
That’s actually the real lesson from the experiment. The detectors impart a small but real energy barrier and change the distribution pattern of the electron
Basically if you hold up a ruler to something human scale it doesn’t effect the thing your measuring much. But when you are trying to measure a basketball with something the size of a gymnasium you have to really launch that fucking basketball to open a door and the door has a very noticeable affect on the trajectory of the ball.
starman2112@sh.itjust.works
on 11 Sep 08:13
nextcollapse
My understanding is that they use something like polarizing filters. Both slits have the same filter, they make a diffusion pattern as the waves interfere with each other. Both slits have different filters, there’s no wave interference and you get two lines.
Calling it an “observer” is maybe the most damaging name in the sciences since some douchebag decided to call the orthoganal number line “imaginary”
As far as I understand as a layman, the measurement tool doesn’t really matter. Any observer needs to interact with the photon in order to observe it and so even the best experiment will always cause this kind of behavior.
With no observer: the photon, acting as a wave, passes through both slits simultaneously and on the other side of the divider, starts to interfere with itself. Where the peaks or troughs of the wave combine is where the photon is most likely to hit the screen in the back. In order to actually see this interference pattern we need to send multiple photons through. Each photon essentially lands in a random location and the pattern only reveals itself as we repeat the experiment. This is important for the next part…
With an observer: the photon still passes through both slits. However, the interaction with the observer’s wave function causes the part of the photon’s wave in that slit to offset in phase. In other words, the peaks and troughs are no longer in the same place. So now the interference pattern that the photon wave forms with itself still exists but, critically, it looks completely different.
Now we repeat with more photons. BUT each time you send a photon through it comes out with a different phase offset. Why? Because the outcome of the interaction with the observer is governed by quantum randommess. So every photon winds up with a different interference pattern which means that there’s no consistency in where they wind up on the screen. It just looks like random noise.
At least that’s what I recall from an episode of PBS Space Time.
The interference pattern disappears if anything becomes entangled with the which-way information at all, it doesn’t need to even be an “observer” (unless you are using “observer” broadly enough that it can include even a single particle). You can replace the entire measurement device with a single particle that interacts with the particles at the slits in such a way that it becomes perfectly correlated with the which-way information that the observer has no awareness of (such as if a moat of dust interacts with the particle because the experimenter did not isolate it well) and that is sufficient for the interference pattern to disappear.
threaded - newest
I love this.
Marry it, then.
It feels like a very aggressive title for this post.
<img alt="" src="https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Fmedia.tenor.com%2FuWhsgmDxf6QAAAAd%2Fevil-smile-jack-nicholson.gif&f=1&nofb=1&ipt=9795884fed877fad7d0f1749fad9fbdf21e3fed34264c57f1b50374cdaa89e42">
<img alt="" src="https://sh.itjust.works/pictrs/image/cdd518b7-ec79-4057-a2be-c3e70a49fa15.jpeg">
The uncertainty principle has increased … my uncertainty.
I’m not sure about this
gonna keep banging this drum every time this comes up:
When physicists say “observe”, they actually mean “measure”. And to measure a photon of light, you have to interact with it somehow, there is no passive way to do so.
The post’s header image implies that the interference pattern goes away just by looking at it. If that were the case, we would never see the interference pattern, never know it was there in the first place! In the actual experiment, they put a sensor at one or both of the slits. But to “sense” a single photon, you have to interact with it in some way. Otherwise you wouldn’t know it was there.
Again, this is where the language trips us up. Rather than “sensor”, would really be more accurate to say they put a photon-touch-er at the slits.
So, what we actually get is “Touching the photon changes the photon’s behavior.” The universe doesn’t magically infer when we happen to be looking at it, there is no spooky action-at-a-distance!
This guy observes.
Thank you for your service
This reads like an order for the lemmings with the right body parts
<img alt="" src="https://i.kym-cdn.com/entries/icons/facebook/000/028/596/dsmGaKWMeHXe9QuJtq_ys30PNfTGnMsRuHuo_MUzGCg.jpg">
Nice
I see what you did there...
Do you? Do you see it? The other dimensions!?
NO, IT’S IMPOSSIBLE… YOU CAN’T SEE IT.
… (long pause) … (longer pause) …
… (even longer pause) … (pause for dramatic effect) …
… (Pause with a capital P) … Can you?
Do you truly want to know?
Alrighty then, but don't say that I did not warn you:
...
...
...
Yes. Except after I peeked, it no longer exists. But the people - THOSE PEOPLE - they, haha, they hehe they claim that I am the ones who are (sic) crazy, the absolute fools! They refuse to know what I have seen!!
<img alt="" src="https://lemmy.world/pictrs/image/a607f457-bdb4-47d2-9c15-536106c20eee.gif">
Alright, consider the slit observed then...
<img alt="img" src="https://media.tenor.com/rwA3wvGxmE4AAAAM/yay-sarcastic.gif">
I don’t get it. Don’t both top and bottom show interference patterns, or is this about something else?
top is interference patterns (like a wave) while bottom is as if it’s a particle (only two slits)
Oh I see I was overthinking it.
Though as far as I’m aware the patterns usually aren’t that nuanced in reality.
Do you mean that they are not as noisy?
More noisy.
Huh. When looking at light interference patterns I always thought that they looked less noisy, especially when showing a spectrum.
Don’t worry. You were both right and wrong until we observed it.
It’s funny until you meet someone who actually believes that human eyes change quantum results
It’s a reasonable thing to think from the way it was described in my physics class, at least. I fault people a lot less for misunderstanding something that even scientists in the field don’t really understand than for something like thinking the earth is flat.
i fault them for doubling and tripling down when corrected, with sources, because they’d rather keep believing a fantastic lie.
In fairness, there was a whole Journey song about it
I think I’ve meet too many charlatans to be that forgiving about it
Its like punching a hole in folded paper to explain a wormhole. Hollywood science movies have a lot to answer for.
They don’t even explain it in physics class. That is kind of the schtick of the Copenhagen interpretation. You just assume as a postulate that systems are in classical states when you look at them and in quantum states when you do not, and from those two assumptions you can prove using Gleason’s theorem that the only possible way the former can map onto the latter is through the Born rule. But there is no explanation given at all as to how or when or by what mechanism this transition actually takes place.
Many Worlds isn’t much better because they posit that the classical world does not even exist, yet that clearly contradicts with what we directly observe in experiments, so if that is true it necessarily means that the classical world is an illusion, and so then you still have to explain how the illusion comes about, which they do not. Dropping the postulate that there is indeed a classical world also disallows you from deriving the Born rule through Gleason’s theorem, and so it then becomes unclear how to do it at all without some arbitrary additional postulate, and the arbitrary nature of it means there are dozens of proposals of different postulates and no way to decide between them.
Modern physics is of the form (1) there is a quantum state, (2) you look at it, (3) a miracle happens, (4) you perceive a classical state, and then you are repeatedly gaslit into believing quantum mechanics is a complete theory of nature and it’s impossible for there to ever be anything more fundamental than it and any physicist who thinks there might be, even if they are literally Albert Einstein, is a crank crackpot. They then take on the same playbook as the Christians where when you point out their explanation seems to be logically incoherent, they say, “God has no obligation to make sense to you” as an excuse to be incoherent and making no sense, but just replace “God” with “nature” and the same argument is repeated verbatim.
Yeah, those dumbasses. It’s obviously a monkey.
I thought it was some cat.
The book The Quantum Magician makes this mistake
The protagonist has a quantum brain and to use it they have to turn off their consciousness in order to not collapse the superposition. I face palmed whenever they mentioned it
But other then that, totally scientifically accurate.
It was trying to be hard sci-fi but… It’s still a bit magical
Anyone actually know what measurment devices are used to observe which slit the electron passes through? How do we know that a specific measuring tool isn’t changing the experiment significantly enough to cause issues with outcome and that the behavior change is abnormal?
That’s actually the real lesson from the experiment. The detectors impart a small but real energy barrier and change the distribution pattern of the electron
Basically if you hold up a ruler to something human scale it doesn’t effect the thing your measuring much. But when you are trying to measure a basketball with something the size of a gymnasium you have to really launch that fucking basketball to open a door and the door has a very noticeable affect on the trajectory of the ball.
My understanding is that they use something like polarizing filters. Both slits have the same filter, they make a diffusion pattern as the waves interfere with each other. Both slits have different filters, there’s no wave interference and you get two lines.
Calling it an “observer” is maybe the most damaging name in the sciences since some douchebag decided to call the orthoganal number line “imaginary”
As far as I understand as a layman, the measurement tool doesn’t really matter. Any observer needs to interact with the photon in order to observe it and so even the best experiment will always cause this kind of behavior.
With no observer: the photon, acting as a wave, passes through both slits simultaneously and on the other side of the divider, starts to interfere with itself. Where the peaks or troughs of the wave combine is where the photon is most likely to hit the screen in the back. In order to actually see this interference pattern we need to send multiple photons through. Each photon essentially lands in a random location and the pattern only reveals itself as we repeat the experiment. This is important for the next part…
With an observer: the photon still passes through both slits. However, the interaction with the observer’s wave function causes the part of the photon’s wave in that slit to offset in phase. In other words, the peaks and troughs are no longer in the same place. So now the interference pattern that the photon wave forms with itself still exists but, critically, it looks completely different.
Now we repeat with more photons. BUT each time you send a photon through it comes out with a different phase offset. Why? Because the outcome of the interaction with the observer is governed by quantum randommess. So every photon winds up with a different interference pattern which means that there’s no consistency in where they wind up on the screen. It just looks like random noise.
At least that’s what I recall from an episode of PBS Space Time.
The interference pattern disappears if anything becomes entangled with the which-way information at all, it doesn’t need to even be an “observer” (unless you are using “observer” broadly enough that it can include even a single particle). You can replace the entire measurement device with a single particle that interacts with the particles at the slits in such a way that it becomes perfectly correlated with the which-way information that the observer has no awareness of (such as if a moat of dust interacts with the particle because the experimenter did not isolate it well) and that is sufficient for the interference pattern to disappear.