aeronmelon@lemmy.world
on 28 Aug 2024 14:39
nextcollapse
“Greg, we got an order for a lot of unobserved results. Take the rest of the week off.”
jerakor@startrek.website
on 28 Aug 2024 14:54
nextcollapse
2060 job posting, Quantum Stability Engineer.
rebelsimile@sh.itjust.works
on 28 Aug 2024 15:34
nextcollapse
could a record like this be used as a presence detector? Like if there was any observer who collapsed the wave function then we’d get the collapsed lines in the log, otherwise it would have indicated no observers? (obviously even what the hell is an ‘observer’ anyway?)
Rhaedas@fedia.io
on 28 Aug 2024 15:45
nextcollapse
A log is an observance itself. Any measurement changes the state.
rebelsimile@sh.itjust.works
on 28 Aug 2024 15:46
collapse
How is the unobserved state ever known about, then?
CluckN@lemmy.world
on 28 Aug 2024 17:24
nextcollapse
They say, “I’m not peeking” but cross their fingers behind their back.
MrPoopbutt@lemmy.world
on 28 Aug 2024 17:35
nextcollapse
You observe the result, not the experiment while it is running.
ulterno@lemmy.kde.social
on 29 Aug 2024 07:42
nextcollapse
It is “guessed” using whatever mathematical model that matches the system.
Of course, if our whole theory is wrong, then the guess will be wrong and we won’t know unless some condition arises where the predicted result and the observed result are different.
We can observe the end result. E.g. observing the screen only, and you get wavelike behaviour. When you also observe the slit, the wavelike behaviour disappears, and it seems particle like.
Both end in an observation, 1 has an extra observation.
rebelsimile@sh.itjust.works
on 29 Aug 2024 15:55
collapse
yeah so if I looked at a log of all that, wouldn’t I have a “extra observer” detector, then?
You could detect decoherence in the system, that doesn’t indicate a human observer, however.
That process is, however, used to protect cryptographic keys, transfered between banks. A hostile observer collapses the state early. The observer gets the key instead of the 2nd bank, which is extremely conspicuous to both banks.
DragonTypeWyvern@midwest.social
on 28 Aug 2024 18:15
nextcollapse
Yes. Trust me, am science guy.
cynar@lemmy.world
on 28 Aug 2024 21:07
nextcollapse
Observer here doesn’t mean the same as the layman meaning. It’s anything that interacts with the system while it’s developing.
Interestingly, it actually can be used for a presence detector, at least in a sense. You can use it to transfer cryptographic information. If no-one is listening in, about half your sent numbers are wrong, but you can agree on what ones. However, if someone is listening in, all your data gets randomised.
They actually now use this system to transfer information between banks. They send a random stream of 0s and 1s over a fibre optic cable. They then send (semi publicly) which bits made it properly. If someone spliced into the fibre, they would get the encryption data, but the target bank would not! They know instantly that something is wrong.
Yes. This is how motion detectors work. Normally, motion detectors have an IR emitter that acts as a particle, but when someone walks by, the IR emitter works as a wave, triggering the motion detector.
Notably, this doesn’t work with dogs, as they have no souls.
pumpkinseedoil@mander.xyz
on 29 Aug 2024 10:27
collapse
Notably, this doesn’t work with dogs, as they have no souls.
Which kind of motion detectors? The ones I know work on everything that’s moving, including my cats (don’t have dogs) or even just throwing something past it
Etterra@lemmy.world
on 28 Aug 2024 17:47
nextcollapse
Okay so what if you sat in a swivel chair and spun around in circles next to it.
cynar@lemmy.world
on 28 Aug 2024 18:48
nextcollapse
For those confused, it’s worth noting the difference between observed as a layman concept and as a quantum mechanical one.
In QM, to observed is to couple the observer to the “system” being observed. Think of it like “observing” your neighbour, over a fence using a BB gun. When you hit flesh, you know where your neighbour is. Unfortunately, the system has now been fundamentally changed. In a classical system, you could turn down the power, until your neighbour doesn’t notice the hits. Unfortunately, QM imposes fundamental limits on your measurements (heisenburg and his uncertainty principal). In order to observe your neighbour accurately, you need to hit them hard enough that the will also feel it and react differently.
QM behaves in a similar way. Initially, the system is just a single particle, and is not very restrained. This allows it to behave in a very wave like manner. When you observe it, the system now includes the whole observation system, as this coupling propagates, more and more atoms etc get linked. The various restraints cause an effect called decoherence. The system behaves ever more like a classical physical system.
In short, a quantum mechanical “observer” is less sneaky watching, and more hosing down with a machine gun and watching the ricochets.
DumbAceDragon@sh.itjust.works
on 28 Aug 2024 19:53
nextcollapse
Thank you for the explanation! Almost got into an argument a while back because someone was conflating the layman definition with the QM definition as proof of some kinda metaphysical effect of the human consciousness.
NewNewAccount@lemmy.world
on 28 Aug 2024 20:03
nextcollapse
Thanks! I’ve never fully grasped the concept and this really helps.
I’ve always heard it that observing was actually “measuring” and still wasn’t sure why that would impact anything but chalked it up to the quantum world being other-worldly.
Theharpyeagle@lemmy.world
on 29 Aug 2024 06:10
nextcollapse
To be honest I still chalk it up to that.
Wirlocke@lemmy.blahaj.zone
on 29 Aug 2024 08:31
collapse
Honestly physicists don’t actually know what measuring is either. We don’t know when exactly the system is considered “measured” in the chain of entanglement, this is called the Measurement Problem.
Answers range from “shut up don’t think about it” to “there’s an infinite amount of universes split from each other for each quantum event!”.
We know how it works, we just don’t yet understand what is going on under the hood.
In short, quantum effects can be very obvious with small systems. The effects generally get averaged out over larger systems. A measurement inherently entangled your small system with a much larger system diluting the effect.
The blind spot is that we don’t know what a quantum state IS. We know the maths behind it, but not the underlying physics model. It’s likely to fall out when we unify quantum mechanics with general relativity, but we’ve been chipping at that for over 70 years now, with limited success.
pcalau12i@lemmygrad.ml
on 13 Mar 2025 01:50
collapse
We know how it works, we just don’t yet understand what is going on under the hood.
Why should we assume “there is something going on under the hood”? This is my problem with most “interpretations” of quantum mechanics. They are complex stories to try and “explain” quantum mechanics, like a whole branching multiverse, of which we have no evidence for.
It’s kind of like if someone wanted to come up with deep explanation to “explain” Einstein’s field equations and what is “going on under the hood”. Why should anything be “underneath” those equations? If we begin to speculate, we’re doing just tha,t speculation, and if we take any of that speculation seriously as in actually genuinely believe it, then we’ve left the realm of being a scientifically-minded rational thinker.
It is much simpler to just accept the equations at face-value, to accept quantum mechanics at face-value. “Measurement” is not in the theory anywhere, there is no rigorous formulation of what qualifies as a measurement. The state vector is reduced whenever a physical interaction occurs from the reference point of the systems participating in the interaction, but not for the systems not participating in it, in which the systems are then described as entangled with one another.
This is not an “interpretation” but me just explaining literally how the terminology and mathematics works. If we just accept this at face value there is no “measurement problem.” The only reason there is a “measurement problem” is because this contradicts with people’s basic intuitions: if we accept quantum mechanics at face value then we have to admit that whether or not properties of systems have well-defined values actually depends upon your reference point and is contingent on a physical interaction taking place.
Our basic intuition tells us that particles are autonomous entities floating around in space on their lonesome like little stones or billiard balls up until they collide with something, and so even if they are not interacting with anything at all they meaningfully can be said to “exist” with well-defined properties which should be the same properties for all reference points (i.e. the properties are absolute rather than relational). Quantum mechanics contradicts with this basic intuition so people think there must be something “wrong” with it, there must be something “under the hood” we don’t yet understand and only if we make the story more complicated or make a new discovery one day we’d “solve” the “problem.”
Einstein once said, God does not place dice, and Bohr rebutted with, stop telling God what to do. This is my response to people who believe in the “measurement problem.” Stop with your preconceptions on how reality should work. Quantum theory is our best theory of nature and there is currently no evidence it is going away any time soon, and it’s withstood the test of time for decades. We should stop waiting for the day it gets overturned and disappears and just accept this is genuinely how reality works, accept it at face-value and drop our preconceptions. We do not need any additional “stories” to explain it.
The blind spot is that we don’t know what a quantum state IS. We know the maths behind it, but not the underlying physics model.
What is a physical model if not a body of mathematics that can predict outcomes? The physical meaning of the quantum state is completely unambiguous, it is just a list of probability amplitudes. Probability captures the likelihoods of certain outcomes manifesting during an interaction, although quantum probability amplitudes are somewhat unique in that they are complex-valued, but this is to add the additional degrees of freedom needed to simultaneously represent interference phenomena. The state vector is a mathematical notation to capture likelihoods of events occurring while accounting for interference effects.
It’s likely to fall out when we unify quantum mechanics with general relativity, but we’ve been chipping at that for over 70 years now, with limited success.
There has been zero “progress” because the “problem” of unifying quantum mechanics and general relativity is a pseudoproblem. It stems from a bias that because we had success quantizing all the fundamental forces except gravity, then therefore gravity should be quantizable. Since the method that worked for all other forces failed, this being renormalization, all these other theories search for a different way to do it.
But (1) there is no reason other than blind faith to think gravity should be quantized, and (2) there is no direct compelling evidence that either quantum mechanics or general relativity are even wrong.
Also, we can alrea
Zoboomafoo@slrpnk.net
on 29 Aug 2024 11:01
nextcollapse
Sure, but that still means the photons derender when nobody is watching them
Depends on how you are observing it photons impart energy and momentum. The true, detailed explanation is a lot more convoluted, it’s all wave interactions, in the complex plane. However, digesting that into something a layman can follow is difficult.
The main point I was trying to get across is that there is no such thing as an independent, external measurement. Your measurement systems minimum interaction is no longer negligible. How that is done varies, but it always changes the target and becomes part of the equations.
iAvicenna@lemmy.world
on 29 Aug 2024 10:08
nextcollapse
in a nutshell: punch particles in the face, get surprised they behave differently
threaded - newest
I observe what you did there.
<img alt="" src="https://hexbear.net/pictrs/image/6942a5a3-fba3-48ec-9df9-5485acf7235e.gif">
“Greg, we got an order for a lot of unobserved results. Take the rest of the week off.”
2060 job posting, Quantum Stability Engineer.
could a record like this be used as a presence detector? Like if there was any observer who collapsed the wave function then we’d get the collapsed lines in the log, otherwise it would have indicated no observers? (obviously even what the hell is an ‘observer’ anyway?)
A log is an observance itself. Any measurement changes the state.
How is the unobserved state ever known about, then?
They say, “I’m not peeking” but cross their fingers behind their back.
You observe the result, not the experiment while it is running.
It is “guessed” using whatever mathematical model that matches the system.
Of course, if our whole theory is wrong, then the guess will be wrong and we won’t know unless some condition arises where the predicted result and the observed result are different.
We can observe the end result. E.g. observing the screen only, and you get wavelike behaviour. When you also observe the slit, the wavelike behaviour disappears, and it seems particle like.
Both end in an observation, 1 has an extra observation.
yeah so if I looked at a log of all that, wouldn’t I have a “extra observer” detector, then?
You could detect decoherence in the system, that doesn’t indicate a human observer, however.
That process is, however, used to protect cryptographic keys, transfered between banks. A hostile observer collapses the state early. The observer gets the key instead of the 2nd bank, which is extremely conspicuous to both banks.
Yes. Trust me, am science guy.
Observer here doesn’t mean the same as the layman meaning. It’s anything that interacts with the system while it’s developing.
Interestingly, it actually can be used for a presence detector, at least in a sense. You can use it to transfer cryptographic information. If no-one is listening in, about half your sent numbers are wrong, but you can agree on what ones. However, if someone is listening in, all your data gets randomised.
They actually now use this system to transfer information between banks. They send a random stream of 0s and 1s over a fibre optic cable. They then send (semi publicly) which bits made it properly. If someone spliced into the fibre, they would get the encryption data, but the target bank would not! They know instantly that something is wrong.
Yes. This is how motion detectors work. Normally, motion detectors have an IR emitter that acts as a particle, but when someone walks by, the IR emitter works as a wave, triggering the motion detector.
Notably, this doesn’t work with dogs, as they have no souls.
Which kind of motion detectors? The ones I know work on everything that’s moving, including my cats (don’t have dogs) or even just throwing something past it
Oh, you might have one of the newer ones that use interferometry to detect soulless entities.
<img alt="" src="https://media.tenor.com/v3g7aQJt4qQAAAAe/changes-changed.png">
Okay so what if you sat in a swivel chair and spun around in circles next to it.
For those confused, it’s worth noting the difference between observed as a layman concept and as a quantum mechanical one.
In QM, to observed is to couple the observer to the “system” being observed. Think of it like “observing” your neighbour, over a fence using a BB gun. When you hit flesh, you know where your neighbour is. Unfortunately, the system has now been fundamentally changed. In a classical system, you could turn down the power, until your neighbour doesn’t notice the hits. Unfortunately, QM imposes fundamental limits on your measurements (heisenburg and his uncertainty principal). In order to observe your neighbour accurately, you need to hit them hard enough that the will also feel it and react differently.
QM behaves in a similar way. Initially, the system is just a single particle, and is not very restrained. This allows it to behave in a very wave like manner. When you observe it, the system now includes the whole observation system, as this coupling propagates, more and more atoms etc get linked. The various restraints cause an effect called decoherence. The system behaves ever more like a classical physical system.
In short, a quantum mechanical “observer” is less sneaky watching, and more hosing down with a machine gun and watching the ricochets.
Thank you for the explanation! Almost got into an argument a while back because someone was conflating the layman definition with the QM definition as proof of some kinda metaphysical effect of the human consciousness.
Thanks! I’ve never fully grasped the concept and this really helps.
I’ve always heard it that observing was actually “measuring” and still wasn’t sure why that would impact anything but chalked it up to the quantum world being other-worldly.
To be honest I still chalk it up to that.
Honestly physicists don’t actually know what measuring is either. We don’t know when exactly the system is considered “measured” in the chain of entanglement, this is called the Measurement Problem.
Answers range from “shut up don’t think about it” to “there’s an infinite amount of universes split from each other for each quantum event!”.
We know how it works, we just don’t yet understand what is going on under the hood.
In short, quantum effects can be very obvious with small systems. The effects generally get averaged out over larger systems. A measurement inherently entangled your small system with a much larger system diluting the effect.
The blind spot is that we don’t know what a quantum state IS. We know the maths behind it, but not the underlying physics model. It’s likely to fall out when we unify quantum mechanics with general relativity, but we’ve been chipping at that for over 70 years now, with limited success.
Why should we assume “there is something going on under the hood”? This is my problem with most “interpretations” of quantum mechanics. They are complex stories to try and “explain” quantum mechanics, like a whole branching multiverse, of which we have no evidence for.
It’s kind of like if someone wanted to come up with deep explanation to “explain” Einstein’s field equations and what is “going on under the hood”. Why should anything be “underneath” those equations? If we begin to speculate, we’re doing just tha,t speculation, and if we take any of that speculation seriously as in actually genuinely believe it, then we’ve left the realm of being a scientifically-minded rational thinker.
It is much simpler to just accept the equations at face-value, to accept quantum mechanics at face-value. “Measurement” is not in the theory anywhere, there is no rigorous formulation of what qualifies as a measurement. The state vector is reduced whenever a physical interaction occurs from the reference point of the systems participating in the interaction, but not for the systems not participating in it, in which the systems are then described as entangled with one another.
This is not an “interpretation” but me just explaining literally how the terminology and mathematics works. If we just accept this at face value there is no “measurement problem.” The only reason there is a “measurement problem” is because this contradicts with people’s basic intuitions: if we accept quantum mechanics at face value then we have to admit that whether or not properties of systems have well-defined values actually depends upon your reference point and is contingent on a physical interaction taking place.
Our basic intuition tells us that particles are autonomous entities floating around in space on their lonesome like little stones or billiard balls up until they collide with something, and so even if they are not interacting with anything at all they meaningfully can be said to “exist” with well-defined properties which should be the same properties for all reference points (i.e. the properties are absolute rather than relational). Quantum mechanics contradicts with this basic intuition so people think there must be something “wrong” with it, there must be something “under the hood” we don’t yet understand and only if we make the story more complicated or make a new discovery one day we’d “solve” the “problem.”
Einstein once said, God does not place dice, and Bohr rebutted with, stop telling God what to do. This is my response to people who believe in the “measurement problem.” Stop with your preconceptions on how reality should work. Quantum theory is our best theory of nature and there is currently no evidence it is going away any time soon, and it’s withstood the test of time for decades. We should stop waiting for the day it gets overturned and disappears and just accept this is genuinely how reality works, accept it at face-value and drop our preconceptions. We do not need any additional “stories” to explain it.
What is a physical model if not a body of mathematics that can predict outcomes? The physical meaning of the quantum state is completely unambiguous, it is just a list of probability amplitudes. Probability captures the likelihoods of certain outcomes manifesting during an interaction, although quantum probability amplitudes are somewhat unique in that they are complex-valued, but this is to add the additional degrees of freedom needed to simultaneously represent interference phenomena. The state vector is a mathematical notation to capture likelihoods of events occurring while accounting for interference effects.
There has been zero “progress” because the “problem” of unifying quantum mechanics and general relativity is a pseudoproblem. It stems from a bias that because we had success quantizing all the fundamental forces except gravity, then therefore gravity should be quantizable. Since the method that worked for all other forces failed, this being renormalization, all these other theories search for a different way to do it.
But (1) there is no reason other than blind faith to think gravity should be quantized, and (2) there is no direct compelling evidence that either quantum mechanics or general relativity are even wrong.
Also, we can alrea
Sure, but that still means the photons derender when nobody is watching them
I mean, how else are you going to optimise an open world simulation this big?
That’s a pretty misleading explanation. You’re not applying any force to the system by observing it.
Depends on how you are observing it photons impart energy and momentum. The true, detailed explanation is a lot more convoluted, it’s all wave interactions, in the complex plane. However, digesting that into something a layman can follow is difficult.
The main point I was trying to get across is that there is no such thing as an independent, external measurement. Your measurement systems minimum interaction is no longer negligible. How that is done varies, but it always changes the target and becomes part of the equations.
in a nutshell: punch particles in the face, get surprised they behave differently
.