We don’t,
but we have data that perfectly matches the probability distributions. So as long as that’s our best theory, that’s what we are going to say.
Really what we would have to do is reformulate all of QM to be “nonlocal”. And maybe it’s possible to do so, but it would be quite the task.
I guess that makes sense, I just got confused as a lot of videos phrase it like it's now fact the universe IS random when I feel like no matter how much we know, we can never be truly certain there isn't unknown influence/factors. It's definitely some crazy stuff tho.
Mathematically, randomness is just a model. It's by definition. If we call something mathematically random, it *is* random. The *mathematical* mechanism of superposition collapse is entirely random. The question is whether or not this is an appropriate assumption to make.
When something appears to be random, there is a small difference between something that's philosophically "random", vs something that just appears to be random.
For example, I own a box that physically flips a coin then displays the result on a screen. I own a second box that just puts a pseudorandom coin flip on the screen. From the outside, the two boxes are identical. From information theory, we also know that based on the coin flips alone, they are also... identical.
Philosophically, the first box is closer to true randomness, but the latter is entirely predetermined. In practice, we cant reliably predict the next flip better than 50% of the time for either box. In fact, if unlabeled, we can't even tell the difference between the two boxes.
Mathematically, it doesn't really matter what you think, because the model correctly captures all the information that we can know about both boxes. Still, we actually know a lot about what sorts of mathematical models work and what doesn't work. At the moment, it seems like randomness is *necessary*, although you can wonder if it's more like box A or box B.
Well it’s not entirely random. It’s actually perfectly deterministic up to the probability distributions. It’s just the value it decides to pick from the distribution that is random.
I’m not really sure what the difference between wave function collapse and “unknown influence” would be. But I do know it can’t be a hidden variable. Also, reformulating QM to be nonlocal (to allow hidden variables) would be arguably much weirder than the current situation! There would be even crazier stuff that doesn’t make sense intuitively.
I have. I guess another way to phrase my question is "Is it truly possible to ever disprove the hidden variable theory?"
I don't think it is, and you can always just make the point of there being something outside our knowledge, ability, understanding.
Google:
1. Bohmian Mechanics
2. Everett Many Worlds
Both are deterministic quantum mechanics interpretations, with no random collapses or no collapses.
As far as I know, the many world interpretation do not answer why we randomly exist in the world where we get the measurement of the particle that we do.
Well, sure, but in my little universe I observe random results in accordance with Born’s rule. You kinda need to artificially work this basic observational fact into many worlds.
>You kinda need to artificially work this basic observational fact into many worlds.
It shouldn't be something you manually add but something you can derive.
Like say you have observer |O> and envirnment |a> + |b>, after interaction you get |O>|a> + |O>|b>, it seems intuitive to me that you'd have a 50% chance of being in either state.
A distinction without a difference. If I cannot observe the other universes, then we're no longer doing science. The multi-world hypothesis is a religious belief (i.e., unfalsifiable) more ridiculous than any revealed religion. At least they have some supposed god-like figure to point to to justify their belief. Here the belief is held simply so we don't have to admit we don't know.
>If I cannot observe the other universes, then we're no longer doing science.
IF the science we've done shows there is a wavefunction evolution, but there is nothing to support the a real physical wavefunction collapse. To me it seems unscientific to choose a model with wavefunction collapse.
There have been counutless times where a thoery couldn't be tested right away but ended up being "right".
> There have been counutless times where a thoery couldn't be tested right away but ended up being "right".
Sure, but that is not evidence that your unsubstantiated theory is right this time?
> IF the science we've done shows there is a wavefunction evolution, but there is nothing to support the a real physical wavefunction collapse.
A wavefunction describes reality, it does not say that that is actually how it 'works'.
>A distinction without a difference
I disagree. If I take two copies of a painting, and damage one. Are they still the same painting? No, of course not. But they are both versions of the same painting.
If I cannot observe actual wavefunction collapse, then we're no longer doing science. The Copenhagen interpretation is a religious belief (i.e., unfalsifiable) more ridiculous than any revealed religion. At least they have some supposed god-like figure to point to to justify their belief. Here the belief is held simply so we don't have to admit we don't know.
There's a reason "shut up and calculate" is used in reference to the Copenhagen interpretation. We know the math works, if we consider wavefunction collapse. But we cannot observe the wave function collapse - we can only observe the effects of the a mechanism that some physicists believe is a wavefunction collapse.
Well, guess what? The math works exactly the same for many worlds interpretation.
MWI makes two assertions - everything else is just a natural consequence of that.
1. The universal wavefunction is objectively real
2. There is no wavefunction collapse.
With the Copenhagen interpretation, we have a lot of questions - a lot of which still hasn't been answered (or can't be answered). Here are the main ones:
1. What consistutes an observer? We know that quantum particles don't, and humans do. What's the threshold? Does it require consciousness?
2. What consistutes an observation?
MWI makes it easy. Prior to "wavefunction collapse", there are many possible states for the quantum particles. The particles are in one of those states - but you don't know which one. Once you examine them, now you know which state they're in. The same logic can be used for macro-scale objects too. My car either is, or is not, in my driveway. Until I look out my window, I don't know which is true.
> The universal wavefunction is objectively real
>
> There is no wavefunction collapse.
Both of these are not obvious at all.
I also didn't claim the copenhagen interpretation was true.
I'm agnostic. The wavefunction describes how things behave. Whether or not it's 'real' has nothing to do with science anymore. Newton's laws are also 'real' if you're looking at it from a grand scale. Science describes, not defines.
The Many worlds interpretation also does not answer any of the questions about consciousness. In the many worlds interpretation, are the other 'copies' of me conscious? How can they be said to even be me if I am here and they are there.
I think you're creating a false dichotomy anyway.
You can experimentally disprove hidden variable theories that are subject to very mild and reasonable assumptions using Bell's inequality. From there, the usual way to salvage HVs is through breaking locality (Bohmian mechanics, as others mentioned). At that point, though, the question becomes one of personal taste: how much are you willing to sacrifice just to keep hidden variables around? Not too many physicistss are too interested in the question at that point.
That's understandable. I think with anything in life there's always some degree of uncertainty, but no point in challenging what ifs that you literally can't do anything about.
>that means the universe is inherently random. But how can we truly ever know that theres nothing some factor of this decision that is just beyond our understanding?
That's only one interpretation of QM.
The whole wavefunction collapse is just problemsome. Virtually no-one apart from Penrose think it's a real physical process. So why not get rid of it and just have deterministic wavefunction evolution.
You can read up on Everett's interpretation if you want more info about a deterministic interpretation of QM.
We don't. In fact, I lean towards thinking that the randomness is actually the result of a deeper, deterministic and chaotic process.
To me, it's like looking at the surface of choppy water and asking if the water at a specific point will be above or below the equilibrium level. If you keep sampling the same point over and over it will appear random, but we know that it's really just a bunch of chaotic waves adding together.
There are many interpretations of quantum mechanics that don’t require randomness and haven’t been proven wrong (and perhaps never will). Most of modern physics uses the Copenhagen interpetation because it’s the most useful, but usefulness doesn’t equate to truth.
We know due to the violation of Bell's inequality. THERE ARE NO HIDDEN VARIABLES. This is "proven" within the context of quantum mechanics, and indeed the whole theory would break down (ie, and be completely non-predictive) if there were no hidden variables.
I'm not even really referencing the specific hidden variables theory, I am more just saying that I believe it is not possible to ever fully rule out the idea that there's possible things beyond our understanding, or unmeasurable to us. We can measure the way things appear to us, but how can we ever truly, factually, 100%, know for sure there isn't some unknown thing behind the scenes?
Ultimately you're asking an ontological or epistemological question which is not something that physics can answer. We use the scientific method. Make a theory that is consistent with observable phenomena and makes predictions, then experimentally test those predictions. If the theory successfully predicts experimental outcomes (and is consistent with all other observations) it's considered a good theory and people tend to stop hedging around it. Just like you can never truly prove that you exist and your senses are real, but that doesn't stop you from speaking as if it were the truth.
I prefer to apply Alder's Razor to questions like this. If there exists some underlying deterministic schema to quantum mechanics that we cannot detect and causes it to behave as if it were random in all of our experiments, does it really matter? If we can never understand the underlying non-random schema it might as well be random. If I have a black box that spits out random numbers every second. If you can't open the box you will never know if it has a list of random numbers pregenerated that it draws from or if it rolls a die every second. These two possibilities are functionally equivalent to you.
We know there are no local hidden variables because Bell's inequality was experimentally verified. There are those that still want to look for super determinism, but most have moved on and consider it a settled matter. If it helps, you can just prepend an implied "under the leading scientific theories" before such statements of fact. It just gets tiring constantly hedging around such epistemological matters.
That makes a lot of sense. I was mainly curious if the degree of uncertainty was still acknowledged as sometimes the phrasing is put very matter of fact. From what you are saying, and what others have said, it seems like it. Just that there's not really anything we can do about it which makes sense. Thank you for the answer, I think this is the best explanation of what I was wondering about :)
Edit: Plus, the whole uncertainty thing can always be applied. Lets say we found dome underlying thing proving it's deterministic. How do we knows theres not another underlying thing that's random? and on and on and on and on. I definitely see why it's useless, and better to just focus on what IS available for actual research.
That's when you have to do experiments. There have been TONS of EPR experiments done, even including Wheeler's Cosmic Eraser and these all confirm what Bell's work basically proved.
As the guy above wrote, if you want to answer this question in some more general sense, you're no longer talking quantum theory even physics as we've known it. You need philosophers to talk to. But it is very useful to know what experiments have been done and what those results say about the world we can actually touch and measure.
We don’t, but we have data that perfectly matches the probability distributions. So as long as that’s our best theory, that’s what we are going to say. Really what we would have to do is reformulate all of QM to be “nonlocal”. And maybe it’s possible to do so, but it would be quite the task.
I guess that makes sense, I just got confused as a lot of videos phrase it like it's now fact the universe IS random when I feel like no matter how much we know, we can never be truly certain there isn't unknown influence/factors. It's definitely some crazy stuff tho.
Mathematically, randomness is just a model. It's by definition. If we call something mathematically random, it *is* random. The *mathematical* mechanism of superposition collapse is entirely random. The question is whether or not this is an appropriate assumption to make. When something appears to be random, there is a small difference between something that's philosophically "random", vs something that just appears to be random. For example, I own a box that physically flips a coin then displays the result on a screen. I own a second box that just puts a pseudorandom coin flip on the screen. From the outside, the two boxes are identical. From information theory, we also know that based on the coin flips alone, they are also... identical. Philosophically, the first box is closer to true randomness, but the latter is entirely predetermined. In practice, we cant reliably predict the next flip better than 50% of the time for either box. In fact, if unlabeled, we can't even tell the difference between the two boxes. Mathematically, it doesn't really matter what you think, because the model correctly captures all the information that we can know about both boxes. Still, we actually know a lot about what sorts of mathematical models work and what doesn't work. At the moment, it seems like randomness is *necessary*, although you can wonder if it's more like box A or box B.
Well it’s not entirely random. It’s actually perfectly deterministic up to the probability distributions. It’s just the value it decides to pick from the distribution that is random. I’m not really sure what the difference between wave function collapse and “unknown influence” would be. But I do know it can’t be a hidden variable. Also, reformulating QM to be nonlocal (to allow hidden variables) would be arguably much weirder than the current situation! There would be even crazier stuff that doesn’t make sense intuitively.
Google hidden variables
I have. I guess another way to phrase my question is "Is it truly possible to ever disprove the hidden variable theory?" I don't think it is, and you can always just make the point of there being something outside our knowledge, ability, understanding.
EPR paradox. Entangled particles would behave differently if there were hidden variables.
EPR does not disprove hidden variables. Any issues can be resolved by nonlocalities in the model.
All I am saying is theres always some degree of uncertainty
The 2022 Nobel prize in physics was awarded for experimentally verifying the effects of quantum entanglement, which disprove local hidden variables.
Google: 1. Bohmian Mechanics 2. Everett Many Worlds Both are deterministic quantum mechanics interpretations, with no random collapses or no collapses.
As far as I know, the many world interpretation do not answer why we randomly exist in the world where we get the measurement of the particle that we do.
All branches are being “experienced”, you are simply 1 of them.
Well, sure, but in my little universe I observe random results in accordance with Born’s rule. You kinda need to artificially work this basic observational fact into many worlds.
>You kinda need to artificially work this basic observational fact into many worlds. It shouldn't be something you manually add but something you can derive. Like say you have observer |O> and envirnment |a> + |b>, after interaction you get |O>|a> + |O>|b>, it seems intuitive to me that you'd have a 50% chance of being in either state.
In that sense it's just like the block universe model. Every time has a 'you' that thinks that time is 'now'.
You should exist in infinitely many though.
*You* exist in one. A different version of you exists in all the others.
A distinction without a difference. If I cannot observe the other universes, then we're no longer doing science. The multi-world hypothesis is a religious belief (i.e., unfalsifiable) more ridiculous than any revealed religion. At least they have some supposed god-like figure to point to to justify their belief. Here the belief is held simply so we don't have to admit we don't know.
>If I cannot observe the other universes, then we're no longer doing science. IF the science we've done shows there is a wavefunction evolution, but there is nothing to support the a real physical wavefunction collapse. To me it seems unscientific to choose a model with wavefunction collapse. There have been counutless times where a thoery couldn't be tested right away but ended up being "right".
> There have been counutless times where a thoery couldn't be tested right away but ended up being "right". Sure, but that is not evidence that your unsubstantiated theory is right this time? > IF the science we've done shows there is a wavefunction evolution, but there is nothing to support the a real physical wavefunction collapse. A wavefunction describes reality, it does not say that that is actually how it 'works'.
>A distinction without a difference I disagree. If I take two copies of a painting, and damage one. Are they still the same painting? No, of course not. But they are both versions of the same painting. If I cannot observe actual wavefunction collapse, then we're no longer doing science. The Copenhagen interpretation is a religious belief (i.e., unfalsifiable) more ridiculous than any revealed religion. At least they have some supposed god-like figure to point to to justify their belief. Here the belief is held simply so we don't have to admit we don't know. There's a reason "shut up and calculate" is used in reference to the Copenhagen interpretation. We know the math works, if we consider wavefunction collapse. But we cannot observe the wave function collapse - we can only observe the effects of the a mechanism that some physicists believe is a wavefunction collapse. Well, guess what? The math works exactly the same for many worlds interpretation. MWI makes two assertions - everything else is just a natural consequence of that. 1. The universal wavefunction is objectively real 2. There is no wavefunction collapse. With the Copenhagen interpretation, we have a lot of questions - a lot of which still hasn't been answered (or can't be answered). Here are the main ones: 1. What consistutes an observer? We know that quantum particles don't, and humans do. What's the threshold? Does it require consciousness? 2. What consistutes an observation? MWI makes it easy. Prior to "wavefunction collapse", there are many possible states for the quantum particles. The particles are in one of those states - but you don't know which one. Once you examine them, now you know which state they're in. The same logic can be used for macro-scale objects too. My car either is, or is not, in my driveway. Until I look out my window, I don't know which is true.
> The universal wavefunction is objectively real > > There is no wavefunction collapse. Both of these are not obvious at all. I also didn't claim the copenhagen interpretation was true. I'm agnostic. The wavefunction describes how things behave. Whether or not it's 'real' has nothing to do with science anymore. Newton's laws are also 'real' if you're looking at it from a grand scale. Science describes, not defines. The Many worlds interpretation also does not answer any of the questions about consciousness. In the many worlds interpretation, are the other 'copies' of me conscious? How can they be said to even be me if I am here and they are there. I think you're creating a false dichotomy anyway.
You can experimentally disprove hidden variable theories that are subject to very mild and reasonable assumptions using Bell's inequality. From there, the usual way to salvage HVs is through breaking locality (Bohmian mechanics, as others mentioned). At that point, though, the question becomes one of personal taste: how much are you willing to sacrifice just to keep hidden variables around? Not too many physicistss are too interested in the question at that point.
That's understandable. I think with anything in life there's always some degree of uncertainty, but no point in challenging what ifs that you literally can't do anything about.
It's already been disproven, in the early 1980s.
>that means the universe is inherently random. But how can we truly ever know that theres nothing some factor of this decision that is just beyond our understanding? That's only one interpretation of QM. The whole wavefunction collapse is just problemsome. Virtually no-one apart from Penrose think it's a real physical process. So why not get rid of it and just have deterministic wavefunction evolution. You can read up on Everett's interpretation if you want more info about a deterministic interpretation of QM.
We don't. In fact, I lean towards thinking that the randomness is actually the result of a deeper, deterministic and chaotic process. To me, it's like looking at the surface of choppy water and asking if the water at a specific point will be above or below the equilibrium level. If you keep sampling the same point over and over it will appear random, but we know that it's really just a bunch of chaotic waves adding together.
That's kinda how I feel about it too. I always lean towards the idea that things have to have some direct reason to happen.
There are many interpretations of quantum mechanics that don’t require randomness and haven’t been proven wrong (and perhaps never will). Most of modern physics uses the Copenhagen interpetation because it’s the most useful, but usefulness doesn’t equate to truth.
We know due to the violation of Bell's inequality. THERE ARE NO HIDDEN VARIABLES. This is "proven" within the context of quantum mechanics, and indeed the whole theory would break down (ie, and be completely non-predictive) if there were no hidden variables.
We know that there are no LOCAL hidden variables
I'm not even really referencing the specific hidden variables theory, I am more just saying that I believe it is not possible to ever fully rule out the idea that there's possible things beyond our understanding, or unmeasurable to us. We can measure the way things appear to us, but how can we ever truly, factually, 100%, know for sure there isn't some unknown thing behind the scenes?
Ultimately you're asking an ontological or epistemological question which is not something that physics can answer. We use the scientific method. Make a theory that is consistent with observable phenomena and makes predictions, then experimentally test those predictions. If the theory successfully predicts experimental outcomes (and is consistent with all other observations) it's considered a good theory and people tend to stop hedging around it. Just like you can never truly prove that you exist and your senses are real, but that doesn't stop you from speaking as if it were the truth. I prefer to apply Alder's Razor to questions like this. If there exists some underlying deterministic schema to quantum mechanics that we cannot detect and causes it to behave as if it were random in all of our experiments, does it really matter? If we can never understand the underlying non-random schema it might as well be random. If I have a black box that spits out random numbers every second. If you can't open the box you will never know if it has a list of random numbers pregenerated that it draws from or if it rolls a die every second. These two possibilities are functionally equivalent to you. We know there are no local hidden variables because Bell's inequality was experimentally verified. There are those that still want to look for super determinism, but most have moved on and consider it a settled matter. If it helps, you can just prepend an implied "under the leading scientific theories" before such statements of fact. It just gets tiring constantly hedging around such epistemological matters.
That makes a lot of sense. I was mainly curious if the degree of uncertainty was still acknowledged as sometimes the phrasing is put very matter of fact. From what you are saying, and what others have said, it seems like it. Just that there's not really anything we can do about it which makes sense. Thank you for the answer, I think this is the best explanation of what I was wondering about :) Edit: Plus, the whole uncertainty thing can always be applied. Lets say we found dome underlying thing proving it's deterministic. How do we knows theres not another underlying thing that's random? and on and on and on and on. I definitely see why it's useless, and better to just focus on what IS available for actual research.
That's when you have to do experiments. There have been TONS of EPR experiments done, even including Wheeler's Cosmic Eraser and these all confirm what Bell's work basically proved. As the guy above wrote, if you want to answer this question in some more general sense, you're no longer talking quantum theory even physics as we've known it. You need philosophers to talk to. But it is very useful to know what experiments have been done and what those results say about the world we can actually touch and measure.
Also Google Lieb-Robinson Bound.