It doesn’t. Decoherence is the technical step in the Everett picture defining what a “classical branch” even is and explaining how the state vector branches. Every claim that “Decoherence” somehow offers a distinct interpretation to Everett is pure confusion.
The article asks the same question in the last part, wondering whether it's just randomly selected. MWI proponents have always argued decoherence leads to the entire world being put into superposition as decoherence just spreads entanglement to the environment. The math never says entanglement destroys superposition beyond a certain point of complexity (many different entangled systems forming the environment).
The author does say the approach is a combination of Copenhagen and MWI, removing the outlandish parts of both. Seems to preserve the randomness of the former though.
> MWI proponents have always argued decoherence leads to the entire world being put into superposition as decoherence just spreads entanglement to the environment.
Well, duh. It's not like classic objects actually exist, or the classical/quantum divide: everything is quantum, including the "observers". The "classical observer" is a crude approximation that breaks down to a pointy enough question. Just like shorting the perfect battery (with zero internal resistance) with a perfect wire (with zero external resistance) — this scenario is not an approximation of any possible real scenario so it's paradoxicality (infinite current!) is irrelevant.
Random is a very interesting concept. In relation to nature we seem to use "random" as anything we can't or are currently unable to model.
To call something random doesn't mean it's impossible to model, in fact all sorts of natural facts seemed random one day before being covered by a model. One very relatable example example is the motion of stars in the the night sky, which seemed random for ages, until the Copernican revolution.
The fact we have access to random() function in programming seems to trip many people. random() is a particular model implementation of random, but stuff in nature isn't random().
My point is, using "just random" to do work in any scientific explanation is a clutch.
In science randomness is usually used to abstract over a large number of possible paths that result in some outcome without having to reason individually about any specific path or all such paths.
It does not have to mean something inherently non-deterministic or something that can't be modelled, although it certainly is the case that if something is inherently non-deterministic then it would necessarily have to be modelled randomly. Modelling things as a random process is very useful even in cases where the underlying phenomenon has a fully understood and deterministic model; a simple example of this would be chess. It's an entirely deterministic game with perfect information that is fully understood, but nevertheless all the best chess engines model positions probabilistically and use randomness as part of their search.
There's disagreement on this. You seem to just be saying that brute facts or brute contingencies don't exist, but I suspect most scientists would disagree with that.
> None of the leading interpretations of quantum theory are very convincing. They ask us to believe, for example, that the world we experience is fundamentally divided from the subatomic realm it’s built from. Or that there is a wild proliferation of parallel universes, or that a mysterious process causes quantumness to spontaneously collapse.
Actually, the "many worlds" "interpretation", simply treats the highly successful equations as meaning what they say.
And it is misnamed. The field equations describe a highly interconnected "web universe" of "tangles" (what I call spans of entangled interactions) and "spangles". (My shorthand for superpositions, i.e. disjoint interactions of particles. Think of all the alternate lines leading from and two distinguishable states, like star patterns.) Basically, a graph of union and intersection relations where all combinations, individually and en masse, are determined exactly by the laws of conservation.
That's an amazingly good property for a theory. And we have it.
By including all consistent versions, no external information is required by the theory. It is informationally complete. A successful objective explanation. With deep experimental support that entanglement and superposition actually exist, because their interactions are easily testable.
In fact, entanglement doesn't "violate" locality, it is the more general case which explains locality. Locality is just tightly coupled entanglement/interaction. Not a fundamental constraint on connections. There is no fundamental "distance", just loose and dense connections. Locality is just what we see wherever there are patterns of dense connections. They are an effect, not a constraint.
Even in the classical world of large (highly tangled) objects, we take it for granted that dependent objects can separate over arbitrarily vast dimensions of space and time and yet return together. If that isn't entanglement over vast distances, what is it? It is a basic property of classical physics. Quantum mechanics reveals more subtlety in those maintained connections, including interactions between connections, but it didn't originate them.
Forces disappear. They become passive in an interesting way. Histories where information cancel, leave structured distribution patterns behind, which to us look like forces. Cancellation is just information being conserved. Not an active force. But the results appear active.
In a similar way to how the evolutionary umbrella seems very smart and creative, when really, it is just poorly adapted individual creatures independently cancelling themselves out blindly, leaving a distributional improvement behind.
There is no additional information needed to explain the effect of quantum "collapse" because it is already explained by the fast bifurcation of disjoint tangles when lots of particles interact in an unorganized manner. It is thermodynamics being thermodynamics.
Anyone attempting to invent a mechanism for "collapse" is like someone trying to explain why the spherical Earth appears "flat" by introducing additional speculative theories. Despite the spherical world theory already explaining why it looks flat locally.
And the only reason to not take the experimentally verified field equations as a plain reading, is the result is "too big" for someone's imagination.
Our everyday experience doesn't limit reality, despite humans having trouble with theories that reveal a bigger reality, over and over and over.
Bluntly: The total field equations preserve information - that is the plain implication and guarantee for having both unions (tangles) and intersections (spangles) of interactions.
Anything else requires a universal firehose of magically appearing information to choose collapses, i.e. particular interactions, in order to explain something already explained. In other words, dressed up voodoo. And by "re-complicating", uh, "re-explaining" the already explained, introduces a ridiculous new puzzle: Where does all that pervasively intrusive relentless injection of information (that determines every single extricable particle interaction!), come from? (Occam is spinning like a particle accelerator in his grave.)
Saying it "Just Happens" is like someone "explaining" their pet version of a creator with "Just Is". It is a psychological non-taulogy for "Don't Ask Questions".
The part that I have trouble wrapping around with many worlds interpretation is how I as an observer end up in one of the many bifurcations. Any links you can share that will help me with understanding that is welcome!
The Stanford Encyclopedia of Philosophy (https://plato.stanford.edu/entries/qm-manyworlds/) goes into this in some depth, and it seems like the right way to think about it is say that "I" in one branch is a different entity than the "I" in a different branch. I have somehow not been able to grok it yet.
And I agree about the naming. I really dislike the name "many worlds interpretation", which seems to imply that we have to postulate the existence of these additional worlds, whereas in fact they are branches of the wavefunction exactly predicted by standard quantum mechanics.
The problem with Many Worlds is that it doesn't place a bound on the number of worlds, so you can't derive the Born Rule from it.
That's quite a serious issues. And arguments against that - like Self-Locating Uncertainty, or Zurek's Envariance - look suspiciously circular if you pull them apart.
There's also the issue that if you don't have a mechanism that constrains probability, you can't say anything about the common mechanism of any of the worlds you're in. Your world may be some kind of lottery-winning statistical freak world which happens to have very unusual properties, and generalising from them is absolutely misleading.
There's no way of testing that, so you end up with something unfalsifiable.
> The problem with Many Worlds is that it doesn't place a bound on the number of worlds, so you can't derive the Born Rule from it.
I have no idea what this means.
Is there a bound on anything in reality, in terms of scale? Beyond its own laws?
There are not really a number of worlds. There is an interleaving of all interactions, so if you zoom out, a smeared landscape across all configurations, from the plank scale up.
And yes it is experimentally validated. This is the theory that everyone accepts in the lab, even as larger scales of experiment continue to progress.
But some people have difficulty believing/visualizing that it continues to work at larger scales. Despite no scale limitation in the theory, no scale related violations ever suggested experimentally, and the strong likely that scale limitations would produce new physics in at-scale observations of our cosmos if they did exist.
> The part that I have trouble wrapping around with many worlds interpretation is how I as an observer end up in one of the many bifurcations.
Pour water down a hill. Water clings to water, and we have hills that already have lots of correlations. We get streams that break up into multiple streams.
How did one stream end up where it is? It seems like a good question, but it is circular. The stream is defined by where it is. You are here (in some circumstance), because the version of you in this circumstance is you.
A transporter accident that creates several versions of you, on several planets with difference colors, doesn't need to explain to each version how they ended up at a planet with their color. Even if for a particular copy, it seems like there should be an answer why they showed up on a planet of a particular specific color. The "why" is just, all paths were taken.
"Hard problem" makes it out to be much more difficult than it actually is. To simplify things a little bit, if you combine a spatiotemporal sense (a sense of bounded being in space and time) with a general predictive ability (the ability to freely extrapolate in time and space from one's surroundings,) "consciousness" arises necessarily. It's what having such senses feels like from the inside; the first-person view. It's a matter of degree, of course.
The writing of Chalmers and its consequences have been a catastrophe for philosophy.
It's not hard at all when you acknowledge that such senses exist in the world, and that you (like others) possess them. As an aside it tends to foster a certain tendency towards empathy.
In essence, you're asking why there's an inside to being a self-modeling system. But "inside" isn't something extraneous, something additional -- rather, it's what "self-modeling" means.
Really the "hard problem" has a very easy answer, but it's a physical/functional answer, and dualists and obscurantists simply don't like it.
The kneejerk response would be: Are you not conscious at this present moment? If we were to modulate your spatiotemporal senses with drugs or a lobotomy, do you doubt that you would be very differently conscious, or perhaps entirely unconscious?
I mean, there is a credible first-person answer to that question of yours, which each man can answer for himself.
But considered more seriously, the "hard problem" is an artifact of treating experience as a separate thing that needs to be generated. If you accept that self-modeling systems bounded in space and time exist, you've already accepted that experience exists -- because experience is what such a system is, from the inside. There's no second step where experience gets added. The question "why is there experience?" is exactly akin to "Why is there an interior to four walls and a roof?" The interior isn't a separate thing; it's necessarily constitutive.
I think you're right, the many worlds interpretation makes the most sense. Unfortunately out current technology is very far from delivering any experimental confirmation or denial of any of the mainstream interpretations.
Are the Mysteries of Quantum Mechanics Beginning to Dissolve? I don’t think so.
Zurek’s Decoherence and Quantum Darwinism is thought-provoking, but it’s still speculation without broad buy-in from researchers. We might need ASI to crack these mysteries — our brains weren’t built for this kind of problem.
I think the brains of our stone age ancestors were not built for relativity either. In the end the normal sequence of generations (having children and then die at some point) offers "re-trainings" of the brains. So, besides waiting/hoping for artificial intelligence, we should continue to make (and train) children. Worked great so far.
What we need are tractable experiments to test these theories.
Maybe ASI can help design these. Until it can, it will just be another voice arguing for one position over another on pretty weak arguments. Right now my money would be more on human researchers finding those experiments, but even among those few are even trying
Quite frankly, Quantum is probably known or solved by a nation state (probably the United States). Similar to AI, they will release it in a safe roll out (as they deem it).
Maybe, but the AI we see in the mainstream today -- generative image/video/text creations and Large Language Model chatbots -- were done via non-governmental public and private companies. And a lot of the work hitting the scene loudly and somewhat prematurely. My understanding is the amount of and type of compute needed for Quantum is pretty intense, so there'd be a huge footprint from its manufacturing to keep it hidden.
"Thus the wave function can’t tell us what the quantum system is like before we measure it. "
Nothing is a particle, all measured things are a probability that we make a certainty when we measure them.
When you stop looking at things as things, but instead, see them as probabilities, it will all make sense. My hand and the beer bottle I pick up are both probabilities. Since the mind cannot navigate the world based on probabilities it turns them into certainties.
Physical science is is the only way we can perceive quantum science. There is no "collapse" outside of our brains perception.
It would be interesting if most of our confusion with quantum mechanics came from treating probabilities as independent when they are actually highly correlated. I don’t really know any physics, but I’m familiar with probability and this type of problem seems to be the most common error in interpreting probabilities.
I don't have any skin in the game, but people should be aware of Induction vs Deduction.
Induction had the earth at the center of the solar system and had the best calculations to predict where Mars was. Copernicus said earth was at the center, the equations were simpler, but were worse at predicting the location of planets.(until we figured out they moved in ellipses)
When we say "All swans are white, because I've never seen a black swan." Its probabilistically true. That is induction. If we found swans didn't have the gene to make black feathers, that would be deduction.
Deduction is probably the most true, if it is true. (But it is often 100% wrong)
Induction is always semi true.
Quantum mechanics seems to be in the stage of induction. Particles are like the earth at the center of the solar system. We need a Copernican revolution.
The author does say the approach is a combination of Copenhagen and MWI, removing the outlandish parts of both. Seems to preserve the randomness of the former though.
Well, duh. It's not like classic objects actually exist, or the classical/quantum divide: everything is quantum, including the "observers". The "classical observer" is a crude approximation that breaks down to a pointy enough question. Just like shorting the perfect battery (with zero internal resistance) with a perfect wire (with zero external resistance) — this scenario is not an approximation of any possible real scenario so it's paradoxicality (infinite current!) is irrelevant.
To call something random doesn't mean it's impossible to model, in fact all sorts of natural facts seemed random one day before being covered by a model. One very relatable example example is the motion of stars in the the night sky, which seemed random for ages, until the Copernican revolution.
The fact we have access to random() function in programming seems to trip many people. random() is a particular model implementation of random, but stuff in nature isn't random().
My point is, using "just random" to do work in any scientific explanation is a clutch.
It does not have to mean something inherently non-deterministic or something that can't be modelled, although it certainly is the case that if something is inherently non-deterministic then it would necessarily have to be modelled randomly. Modelling things as a random process is very useful even in cases where the underlying phenomenon has a fully understood and deterministic model; a simple example of this would be chess. It's an entirely deterministic game with perfect information that is fully understood, but nevertheless all the best chess engines model positions probabilistically and use randomness as part of their search.
Hardly. Some philosophers say that. But I don't take much from philosophers reasoning about physics.
Actually, the "many worlds" "interpretation", simply treats the highly successful equations as meaning what they say.
And it is misnamed. The field equations describe a highly interconnected "web universe" of "tangles" (what I call spans of entangled interactions) and "spangles". (My shorthand for superpositions, i.e. disjoint interactions of particles. Think of all the alternate lines leading from and two distinguishable states, like star patterns.) Basically, a graph of union and intersection relations where all combinations, individually and en masse, are determined exactly by the laws of conservation.
That's an amazingly good property for a theory. And we have it.
By including all consistent versions, no external information is required by the theory. It is informationally complete. A successful objective explanation. With deep experimental support that entanglement and superposition actually exist, because their interactions are easily testable.
In fact, entanglement doesn't "violate" locality, it is the more general case which explains locality. Locality is just tightly coupled entanglement/interaction. Not a fundamental constraint on connections. There is no fundamental "distance", just loose and dense connections. Locality is just what we see wherever there are patterns of dense connections. They are an effect, not a constraint.
Even in the classical world of large (highly tangled) objects, we take it for granted that dependent objects can separate over arbitrarily vast dimensions of space and time and yet return together. If that isn't entanglement over vast distances, what is it? It is a basic property of classical physics. Quantum mechanics reveals more subtlety in those maintained connections, including interactions between connections, but it didn't originate them.
Forces disappear. They become passive in an interesting way. Histories where information cancel, leave structured distribution patterns behind, which to us look like forces. Cancellation is just information being conserved. Not an active force. But the results appear active.
In a similar way to how the evolutionary umbrella seems very smart and creative, when really, it is just poorly adapted individual creatures independently cancelling themselves out blindly, leaving a distributional improvement behind.
There is no additional information needed to explain the effect of quantum "collapse" because it is already explained by the fast bifurcation of disjoint tangles when lots of particles interact in an unorganized manner. It is thermodynamics being thermodynamics.
Anyone attempting to invent a mechanism for "collapse" is like someone trying to explain why the spherical Earth appears "flat" by introducing additional speculative theories. Despite the spherical world theory already explaining why it looks flat locally.
And the only reason to not take the experimentally verified field equations as a plain reading, is the result is "too big" for someone's imagination.
Our everyday experience doesn't limit reality, despite humans having trouble with theories that reveal a bigger reality, over and over and over.
Bluntly: The total field equations preserve information - that is the plain implication and guarantee for having both unions (tangles) and intersections (spangles) of interactions.
Anything else requires a universal firehose of magically appearing information to choose collapses, i.e. particular interactions, in order to explain something already explained. In other words, dressed up voodoo. And by "re-complicating", uh, "re-explaining" the already explained, introduces a ridiculous new puzzle: Where does all that pervasively intrusive relentless injection of information (that determines every single extricable particle interaction!), come from? (Occam is spinning like a particle accelerator in his grave.)
Saying it "Just Happens" is like someone "explaining" their pet version of a creator with "Just Is". It is a psychological non-taulogy for "Don't Ask Questions".
The Stanford Encyclopedia of Philosophy (https://plato.stanford.edu/entries/qm-manyworlds/) goes into this in some depth, and it seems like the right way to think about it is say that "I" in one branch is a different entity than the "I" in a different branch. I have somehow not been able to grok it yet.
And I agree about the naming. I really dislike the name "many worlds interpretation", which seems to imply that we have to postulate the existence of these additional worlds, whereas in fact they are branches of the wavefunction exactly predicted by standard quantum mechanics.
That's quite a serious issues. And arguments against that - like Self-Locating Uncertainty, or Zurek's Envariance - look suspiciously circular if you pull them apart.
There's also the issue that if you don't have a mechanism that constrains probability, you can't say anything about the common mechanism of any of the worlds you're in. Your world may be some kind of lottery-winning statistical freak world which happens to have very unusual properties, and generalising from them is absolutely misleading.
There's no way of testing that, so you end up with something unfalsifiable.
I have no idea what this means.
Is there a bound on anything in reality, in terms of scale? Beyond its own laws?
There are not really a number of worlds. There is an interleaving of all interactions, so if you zoom out, a smeared landscape across all configurations, from the plank scale up.
And yes it is experimentally validated. This is the theory that everyone accepts in the lab, even as larger scales of experiment continue to progress.
But some people have difficulty believing/visualizing that it continues to work at larger scales. Despite no scale limitation in the theory, no scale related violations ever suggested experimentally, and the strong likely that scale limitations would produce new physics in at-scale observations of our cosmos if they did exist.
Pour water down a hill. Water clings to water, and we have hills that already have lots of correlations. We get streams that break up into multiple streams.
How did one stream end up where it is? It seems like a good question, but it is circular. The stream is defined by where it is. You are here (in some circumstance), because the version of you in this circumstance is you.
A transporter accident that creates several versions of you, on several planets with difference colors, doesn't need to explain to each version how they ended up at a planet with their color. Even if for a particular copy, it seems like there should be an answer why they showed up on a planet of a particular specific color. The "why" is just, all paths were taken.
The writing of Chalmers and its consequences have been a catastrophe for philosophy.
The hard problem is that there is such a feeling at all.
In essence, you're asking why there's an inside to being a self-modeling system. But "inside" isn't something extraneous, something additional -- rather, it's what "self-modeling" means.
Really the "hard problem" has a very easy answer, but it's a physical/functional answer, and dualists and obscurantists simply don't like it.
I mean, there is a credible first-person answer to that question of yours, which each man can answer for himself.
But considered more seriously, the "hard problem" is an artifact of treating experience as a separate thing that needs to be generated. If you accept that self-modeling systems bounded in space and time exist, you've already accepted that experience exists -- because experience is what such a system is, from the inside. There's no second step where experience gets added. The question "why is there experience?" is exactly akin to "Why is there an interior to four walls and a roof?" The interior isn't a separate thing; it's necessarily constitutive.
Is it falsifiable?
If you have a theory that seems unassailable by any logic, that's a good signal it is tautological and not very useful.
Zurek’s Decoherence and Quantum Darwinism is thought-provoking, but it’s still speculation without broad buy-in from researchers. We might need ASI to crack these mysteries — our brains weren’t built for this kind of problem.
Maybe ASI can help design these. Until it can, it will just be another voice arguing for one position over another on pretty weak arguments. Right now my money would be more on human researchers finding those experiments, but even among those few are even trying
Nothing is a particle, all measured things are a probability that we make a certainty when we measure them.
When you stop looking at things as things, but instead, see them as probabilities, it will all make sense. My hand and the beer bottle I pick up are both probabilities. Since the mind cannot navigate the world based on probabilities it turns them into certainties.
Physical science is is the only way we can perceive quantum science. There is no "collapse" outside of our brains perception.
Induction had the earth at the center of the solar system and had the best calculations to predict where Mars was. Copernicus said earth was at the center, the equations were simpler, but were worse at predicting the location of planets.(until we figured out they moved in ellipses)
When we say "All swans are white, because I've never seen a black swan." Its probabilistically true. That is induction. If we found swans didn't have the gene to make black feathers, that would be deduction.
Deduction is probably the most true, if it is true. (But it is often 100% wrong)
Induction is always semi true.
Quantum mechanics seems to be in the stage of induction. Particles are like the earth at the center of the solar system. We need a Copernican revolution.