bunchberry
@bunchberry@lemmy.world
- Comment on 33 minutes ago:
Not to be the 🤓 but just so we’re clear, the point of Schrödinger’s cat was to illustrate that you can’t know a quantum state until you measure it. Basically just saying “probability exists.”
That wasn’t Schrödinger’s point at all.
Schrödinger was responding to people in Bohr and von Neumann’s camp who claim that particles described mathematically by a superposition of states literally have no real observables in the real world at all. It is not just that they are random or probabilistic, but people in the “anti-realist” camp argue that they effectively no longer even exist anymore when they are described mathematically by a superposition of states. This position is sometimes called value indefiniteness.
Schrödinger was criticizing this position by pointing out that you cannot separate your beliefs about the microworld from the macroworld, because macroscopic objects like cats are also made up of particles and should follow the same rules. Hence, he puts forward a thought experiment whereby a cat would also be described mathematically in a superposition of states.
If you think superposition of states means it no longer has real definite properties in the real world, then the cat wouldn’t have real define properties in the real world until you open the box. Schrödinger’s point was that this is such an obvious absurdity that we should reject value indefiniteness for individual particles as well.
You say:
The reason it’s a big deal is that this probability is a real property. One that is supposed to be only one of two states. But instead it isn’t really in a state at all until you measure it, and that’s weird.
But that is exactly the point Schrödinger was criticizing, not supporting.
Value indefiniteness / anti-realism ultimately amounts to solipsism because if particles lack real, definite, observable properties in the real world when you are not looking at them, other people are also made up of particles, so other people wouldn’t have real, definite, observable properties in the real world when you are not looking at them.
He was trying to illustrate that this position reduces to an absurdity and so we should not believe in that position.
The point is that instead of assuming it is in one state or the other, you can and often should think of both possibilities at once. This is what makes quantum computing useful.
No. If you perform a polar decomposition on the quantum state, you are left with a probability vector and a phase vector. The probability vector is the same kind of probability vector you use in classical probabilistic computing. The update rule for it in quantum computing literally only differs by an additional term which is a non-linear term that depends upon the phase vector.
The "advantage’ comes from the phase vector. For N qubits, there are 2^N phases. A system of 300 qubits would have 2^300 phases, which is far greater than the number of atoms in the observable universe. A single logic gate thus can manipulate far more states of the system at once because it can manipulate these phases, which the stochastic dynamics of the bits have a dependence upon the phases, and thus you can not only manipulate the phases to do calculations but, if you are clever, you can write the algorithm in such a way that the effect it has on the probability distribution allows you to read off the results from the probability distribution.
The phase vector does not contain anything probabilistic, so it contains nothing that looks like the qubit being in two places at once. That is contained in the probability vector, but there is no good reason to interpret a probability distribution as the system being in two places at once in quantum mechanics than there is in classical mechanics. The advantage comes from the phases, and the state of the phases just can influence the stochastic influence of the bits, and thus can influence the probability distribution.
So you simply apply operations that increase or decrease the chances of certain outcomes and repeat until the answer you want has an incredibly high probability and the rest are nearly zero. Then you measure your qubit, collapsing the wave function, with a high probability that collapse will give you the answer you wanted.
Again, perform a polar decomposition on the quantum state, break it apart into the probability vector and a phase vector. Then, apply a Bayesian knowledge update using Bayes’ theorem to the probability vector, exactly the way you’d do it in classical probabilistic computing. Then, simply undo the polar decomposition, i.e. recompose it back into a single complex-valued vector in Cartesian form.
What you find is that this is mathematically equivalent to the collapse of the wavefunction. The so-called “collapse of the wavefunction” is literally just a Bayesian knowledge update on the degree of freedom of the quantum state associated with the probability distribution of the bits.
It’s less like “the cat is both alive and dead” and more that “the terms ‘alive’ and ‘dead’ do not apply to the cat till you open the box”
Sure, but that position reduces to solipsism, because then you don’t exist until I look at you, either.
- Comment on Gottem 7 hours ago:
Ah, so I see you are going to double-down on trying to defend the indefensible.
They do have values. Their position is just a superposition, rather than one descrete one, which can be described as a wave. Their value is effectively a wave until it’s needed to be discrete.
To quote Dmitry Blokhintsev: “This is essentially a trivial feature known to any experimentalist, and it needs to be mentioned only because it is stated in many textbooks on quantum mechanics that the wave function is a characteristic of the state of a single particle. If this were so, it would be of interest to perform such a measurement on a single particle (say an electron) which would allow us to determine its own individual wave function. No such measurement is possible.”
When I say “real values” I do not mean pure abstract mathematics. We do not live in a Platonic realm. The mathematics are just a tool for predicting what we observe in the real world. Don’t confuse the map for the territory. The abstract wave has no observable properties, it is pure mathematics. If the whole world was just one giant wave in Hilbert space, then this would be equivalent to claiming that the entire world is just one big mathematical function without any observable properties at all, which obviously makes no sense as we can clearly observe the world.
To quote Rovelli: “The gigantic, universal ψ wave that contains all the possible worlds is like Hegel’s dark night in which all cows are black: it does not account, per se, for the phenomenological reality that we actually observe. In order to describe the phenomena that we observe, other mathematical elements are needed besides ψ: the individual variables, like X and P, that we use to describe the world. The Many Worlds interpretation does not explain them clearly. It is not enough to know the ψ wave and Schrödinger’s equation in order to define and use quantum theory: we need to specify an algebra of observables, otherwise we cannot calculate anything and there is no relation with the phenomena of our experience. The role of this algebra of observables, which is extremely clear in other interpretations, is not at all clear in the Many Worlds interpretation.”
Again, as I said in my first comment, any mathematical theory that describes the world needs to, at some point, include symbols which directly refer to something we can observe. An abstract mathematical function contains no such symbols.
This is why you run into contradictions like the “Wigner’s friend” paradox where Wigner would describe his friend in a superposition of states, and if you believe that this literally means that all that exists inside the room is an abstract function, then you cannot explain how the observer in the room can perceive anything that they later claim they do, because there would be no observables inside of the room.
You cannot get around criticisms of solipsism by just promoting purely abstract mathematical entities to being “objective reality” as if objects transform into purely Platonic mathematical functions. At least, if you are going to claim this, then you need some rigorous process to transform them back into something that is described with mathematical language where some of the symbols refer to something we can actually observe such that we can then explain how it is that we can observe it to have the properties that it does when we look at it.
Sure. That doesn’t make the general understanding of the thought experiment accurate. Once the decay of the atom that triggers the poison is detected, it’s no longer in a superposition. It has to not be in order for the detection to occur.
Please scroll up and read my actual comment. You seem to have skipped all the important technical bits, because you are claiming something which is mathematically incompatible with the predictions of quantum mechanics. Your personal self-theory you are inventing here literally would render entanglement impossible.
The double slit experiment shows that an interaction can change the result from wave-like to particle-like behavior.
Decoherence is not relevant here. Decoherence theory works like this:
- Assume that the system+environment become entangled.
- Assume that the observer loses track of the environment.
- Trace out the the environment.
- This leaves you with a reduced density matrix for the system where the coherence terms have dropped to 0.
Notice that step #2 is entirely subjective. We are just assuming that the observer has lost track of the environment in terms of their subjective epistemic access, and step #3 is then akin to statistically marginalizing over the environment in order to then remove it from consideration.
This isn’t an actual physical transition but an epistemic one. The system+environment are still in a coherent superposition of states, and decoherence theory merely shows that it looks like it has decohered if you only have subjective knowledge on a small portion of the much larger coherent superposition of states.
If you believe that a superposition of states means it has no observable properties and is just purely a mathematical function, then decoherence does not solve your problem at all, because it is ultimately a subjective process and not a physical process. If you spent time studying the environment enough before running the experiment such that you could include the environment in your model then decoherence would not occur.
I’m literally not. My entire point is that it isn’t a solipsism. Any interaction causes the waveform to collapse.
Which, again, renders entanglement impossible, since objects must interact to become entangled.
If we accepted your personal self-theory, then quantum computers should be impossible, because the qubits all need to interact many many times over as the algorithm progresses for them to all become entangled and to create a superposition of states of the whole computer’s memory.
You are not listening and advocating things that are trivially wrong.
yet you give no explanation of an alternative. Something is happening. How do you explain it?
I just don’t deny value definiteness. That’s it. There is nothing beyond this.
Consider a perfectly classical world but this world is still fundamentally random. The randomness of interactions would disallow us from tracking the definite values of particles at a given moment in time, so we could only track them with an evolving probability distribution. We can represent this probability distribution with a vector and represent interactions with stochastic matrices. Given that the model does not include observable definite values, would it then be rational to claim that particles suddenly transform into an infinite-dimensional vector in configuration space when you’re not looking at them and lose all their observable properties? No, of course not. The particles still have real observable properties in the real world, but you just lose track of them in the model due to their random evolution.
You could create a simulation where you assign definite values and permute them stochastically at each interaction, and this would produce the same statistical results if you make a measurement at any given step. It is the same with quantum mechanics. It is just a form of non-classical statistical mechanics. There is no empirical, mathematical, or philosophical reason to deny that particles stop possessing real values when you are not looking at them. It is not hard to put together a simulation where the qubits are assigned definite bit values at all times and each logic gate just stochastically permutes those bit values. I even created one myself here. John Bell also showed you can do this with quantum field theory in his paper “Beables for Quantum Field Theory.”
- Comment on Gottem 1 day ago:
You cannot defend value indefiniteness. It is just solipsism. If particles do not have values when you are not looking, then any object made of particles also do not have values when you are not looking. This was the point of Schrodinger’s “cat” thought experiment. This view of “value indefiniteness” you are trying to defend is indefensible because it is literally solipsism and any attempt to promote it above solipsism will just become incoherent.
You say:
it’s when position is needed to be known that causes it. Until then, the position is in a superstate of all possible positions, but for an interaction to occur it needs to be in one position.
This is trivially false, because then it would not be possible for two particles to become entangled on the position basis, which requires them to interact in such a way that depends upon their position values. The other particle would thus need to “know” its position value to become entangled with it, and if this leads to a “collapse,” then such entanglement could not occur. Yet we know it can occur in experiments.
If by “know” you mean humans knowing and not other particles, yeah, okay, but that’s obviously solipsism.
Any attempt to defend value indefiniteness will always either amount to:
- Solipsism
- Something that is trivially wrong
- A theory which is not quantum mechanics (makes different predictions)
This (at least your wording) implies that physics cares about our mathematical models. It doesn’t. Quantum mechanics and “classical” physics are just ways we organize things for education.
I don’t blame them, it is literally the textbook Dirac-von Neumann axioms. That is how it is taught in schools, even though it is obviously incoherent. You are taught that there is a “Heisenberg cut” between the quantum and classical world, with no explanation of how this occurs.
Though we don’t have a model for it, the unvirse is not using two separate models of physics. There is no “quantum mechanics” and “classical physics”. There is only physics.
The problem is that the orthodox interpretation of quantum mechanics does not even allow you to derive classical physics minus gravity in a limiting case from quantum mechanics. It is not even a physical theory of nature at all.
We know from the macroscopic world that particles have real observable properties, yet value indefiniteness denies that they have real observable properties, and it provides no method of telling you when those real, observable properties are added back to the world. It thus cannot make a single empirical prediction at all without this slight-of-hand where they just say, as a matter of axiom in the Dirac-von Neumann textbook axioms of quantum mechanics that it happens “at measurement.”
If measurement is taken to be a subjective observation, then it is just solipsism. If measurement is taken to be a physical process, then it cannot reproduce the mathematical predictions of quantum mechanics, because this “Heisenberg cut” would be a non-reversible process, yet all unitary evolution operators are reversible. Hence, any model which includes a rigorous definition of “measurement” (like Ghirardi–Rimini–Weber theory) would include an additional non-reversible process. You could then just imagine setting up an experiment where this process would occur and then try to reverse it. The mathematics of quantum mechanics and your theory would inevitably lead to different predictions in such a process.
Therefore, again, if you believe in value indefiniteness, then you either (1) are a solipsist, (2) don’t believe in quantum mechanics but think it will be replaced by a physical collapse model, or (3) are confused.
The only way for quantum mechanics to be self-consistent is to reject value indefiniteness, at least as a metaphysical point of view. This does not require actually modifying the mathematics. If nature is random, then of course the definite values will evolve statistically such that they could not be tracked and included in the model. All you would need to then demonstrate is that quantum statistics converges to classical statistics in a limiting case on macroscopic scales, which is achieved by the theory of decoherence.
But the theory of decoherence achieves nothing if you believe in value indefiniteness, because if you believe quantum mechanics has nothing to do with statistics at all, then there is no reason to conclude that what you get in the reduced density matrices after you trace out the environment has anything to do with classical statistics, either.
There is no good argument in the academic literature for value indefiniteness. It is an incoherent worldview based on no empirical evidence at all. People who believe it often just regurgitate mindlessly statements like “Bell’s theorem proves it!” yet cannot articulate what Bell’s theorem even is or how on earth is proves that, especially since Bell himself was the biggest critic of value indefiniteness yet wrote the damned theorem!
- Comment on Just one more square bro 3 weeks ago:
where can i buy one
- Comment on big facts 3 weeks ago:
If you appeal to heat death then you cannot say brains pop back into existence either because “matter has a finite life,” and so it is self-defeating. If brains can pop back into existence due to random fluctuations then surely planets and stars could as well given enough time.
- Comment on big facts 4 weeks ago:
It seems more likely in a universe that is infinitely large that brains would come into existence through simpler deterministic processes like they did on earth than random fluctuations no?
- Comment on Can a reasonable person genuinely believe in ghosts? 4 weeks ago:
Einstein didn’t even get a nobel prize for special relativity because it was considered too radical at the time.
He shouldn’t have gotten one for SR specifically anyways because Hendrik Lorentz had already developed a theory that was mathematically equivalent and presented a year prior to Einstein.
The speed of light can be derived from Maxwell’s equations, which is weird to be able to derive a speed just by analyzing how electromagnetism works, because anyone in any reference frame would derive the same speed, which implies the existence of a universal speed. If the speed is universal, what it is universal to?
Physicists prior to Einstein believed there might be a universal reference frame which defines absolute time and absolute space, these days called a preferred foliation. The Michelson-Morley experiment was an attempt to measure the existence of this preferred foliation because most theories of how it worked would render it detectable in principle, but found no evidence for it.
Most physicists these days retell this experiment as having debunked the idea and led to its replacement with Einstein’s special relativity. But the truth is more complicated than that, because Lorentz found you could patch the idea by just assuming objects physically contract based on their motion relative to preferred foliation. Lorentz’s theory was presented in 1904, a year before Einstein, and was mathematically equivalent, so it makes all the same predictions, and so anything Einstein’s theory would predict, his theory would’ve also predicted.
The reason Lorentz’s theory fell by the wayside is because, by being able to explain the results of the Michelson-Morley experiment which was meant to detect the preferred foliation, it meant it was no longer detectable, and so people liked Einstein’s theory more that threw out this undetectable aspect. But it would still be weird to give Einstein the Nobel prize for what is ultimately just a simplification of Lorentz’s theory.
But there are also good reasons these days to consider putting the preferred foliation back in. The Friedmann solution to Einstein’s general relativity (the solution associated with the universe we actually live in) spontaneously gives rise to a preferred foliation which is actually empirically observable. You can measure your absolute motion relative to the universe by looking at the cosmic dipole in the cosmic background radiation. Since we know you can measure it now and have actually measured our absolute motion in the universe, the argument against Lorentz’s theory is much weaker.
An even stronger argument, however, comes from quantum mechanics. A famous theorem by the physicist John Bell proves the impossibility of “local realism,” and in this case locality means locality in terms of special relativity, and realism means belief that particles have real states in the real physical world independently of you looking at them (called the ontic states) which explain what shows up on your measurement device when you try to measure them. Since many physicists are committed to the idea of special relativity, they conclude that Bell’s theorem must debunk realism, that objective reality does not exist independently of you looking at it, and devolve into bizarre quantum mysticism and weirdness.
But you can equally interpret this to mean that special relativity is wrong and that the preferred foliation needs to put back in. The physicist Hrvoje Nikolic for example published a paper titled “Relativistic QFT from a Bohmian perspective: A proof of concept” showing that you can fit quantum mechanics to a realist theory that reproduces the predictions of relativistic quantum mechanics if you add back in a preferred foliation.
- Comment on it's a long distance relationship 1 month ago:
There is no limit to entanglement as everything is constantly interacting with each other and spreading the entanglement around. That is in fact what decoherence is about, because spreading the entanglement throughout trillions of particles in the environment dilutes it such that quantum interference effects are to subtle to notice, but they are all technically entangled. So if you think entanglement means things are one entity, then you pretty much have to treat the whole universe as one entity. That was the position of Bohm and Blokhintsiev.
- Comment on Save as PDF 1 month ago:
the world is run by PDF files
- Comment on Not that limit 1 month ago:
ChatGPT just gives the correct answer that the limit doesn’t exist.
- Comment on I'm good, thanks 1 month ago:
Depends upon what you mean by realism. If you just mean belief in a physical reality independent of a conscious observer, I am not really of the opinion you need MWI to have a philosophically realist perspective.
For some reason, everyone intuitively accepts the relativity of time and space in special relativity as an ontological feature of the world, but when it comes to the relativity of the quantum state, people’s brains explode and they start treating it like it has to do with “consciousness” or “subjectivity” or something and that if you accept it then you’re somehow denying the existence of objective reality. I have seen this kind of mentality throughout the literature and it has never made sense to me.
Even Eugene Wigner did this, when he proposed the “Wigner’s friend” thought experiment, he points out how two different observers can come to describe the same system differently, and then concludes that proves quantum mechanics is deeply connected to “consciousness.” But we have known that two observers can describe the same system differently since Galileo first introduced the concept of relativity back in 1632. There is no reason to take it as having anything to do with consciousness or subjectivity or anything like that.
(You can also treat the wavefunction nomologically as well, and then the nomological behavior you’d expect from particles would be relative, but the ontological-nomological distinction is maybe getting too much into the weeds of philosophy here.)
I am partial to the way the physicist Francois-Igor Pris puts it. Reality exists as independently of the conscious observer, but not independently from context. You have to specify the context in which you are making an ontological claim for it to have physical meaning. This context can be that of the perspective of a conscious observer, but nothing about the observer is intrinsic here, what is intrinsic is the context, and that is just one of many possible contexts an ontological claim can be made. Two observers can describe the same train to be traveling at different velocities, not because they are conscious observers, but because they are describing the same train from different contexts.
The philosopher Jocelyn Benoist and the physicist Francois-Igor Pris have argued that the natural world does have a kind of an inherent observer-observed divide but that these terms are misleading being “subject” tends to imply a human subject and “observer” tends to imply a conscious observer, and that a lot of the confusion is cleared up once you figure out how to describe this divide in a more neutral, non-anthropomorphic way, which they settle on talking about the “reality” and the “context.” The reality of the velocity of the train will be different in different contexts. You don’t have to invoke “observer-dependence” to describe relativity. Hence, you can indeed describe quantum theory as a theory of physical reality independent of the observer.
- Comment on I'm good, thanks 1 month ago:
MWI very specifically commits to the existence of a universal wavefunction. Everett’s original paper is literally titled “The Theory of the Universal Wavefunction.” If you instead only take relative states seriously, that position is much closer to relational quantum mechanics. In fact, Carlo Rovelli explicitly describes RQM as adopting Everett’s relative-state idea while rejecting the notion of a universal quantum state.
MWI claims there exists a universal quantum state, but quantum theory works perfectly well without this assumption if quantum states are taken to be fundamentally relative. Every quantum state is defined in relation to something else, which is made clear by the Wigner’s friend scenario where different observers legitimately assign different states to the same system. If states are fundamentally relative, then a “universal” quantum state makes about as much sense as a “universal velocity” in Galilean relativity.
You could arbitrarily choose a reference frame in Galilean relativity and declare it universal, but this requires an extra postulate, is unnecessary for the theory, and is completely arbitrary. Likewise, you could pick some observer’s perspective and call that the universal wavefunction, but there is no non-arbitrary reason to privilege it. That wavefunction would still be relative to that observer, just with special status assigned by fiat.
Worse, such a perspective could never truly be universal because it could not include itself. To do that you would need another external perspective, leading to infinite regress. You never obtain a quantum state that includes the entire universe. Any state you define is always relative to something within the universe, unless you define it relative to something outside of the universe, but at that point you are talking about God and not science.
The analogy to Galilean relativity actually is too kind. Galilean relativity relies on Euclidean space as a background, allowing an external viewpoint fixed to empty coordinates. Hilbert space is not a background space at all; it is always defined in terms of physical systems. You can transform perspectives in spacetime, but there is no transformation to a background perspective in Hilbert space because no such background exists. The closet that exists is a statistical transformation to different perspectives within Liouville space, but this only works for objects within the space; you cannot transform to the perspective of the background itself as it is not a background space.
- Comment on I'm good, thanks 1 month ago:
- Entanglement is just a mathematical property of the theory. If it is sufficient to explain measurement then there is not anything particularly unique about MWI since you can employ this explanation within anything. You also say I missed your point by repeating exactly what I said.
- You’re the one giving this bullet point list as if you are debunking all of my points one-by-one. If you agree there is nothing especially “more local” about MWI than any other interpretation then why not just ignore that point and move on?
- A relative state is not an entangled state. Again you need to read the papers I linked. We are talking about observer-dependence in the sense of how the velocity of a train in Galilean relativity can be said to have a different value simultaneously for two different observers. I drew the direct comparison here in order to explain that in my first comment. This isn’t about special relativity or general relativity, but about “relativity” in a more abstract sense of things which are only meaningfully defined as a relational property between systems. The quantum state observer A assigns to a system can be different from the quantum state observer B assigns to the system (see the Wigner’s friend thought experiment). The quantum state in quantum mechanics is clearly relative in this sense, and to claim there is a universal quantum state requires an additional leap which is never mathematically justified.
- Please for the love of god just scroll up and read what I actually wrote in that first post and respond to it. Or don’t. You clearly seem to be entirely uninterested in a serious conversation. I assume you have an emotional attachment to MWI without even having read Everett’s papers and getting too defensive that you refuse to engage seriously in anything I say, so I am ending this conversation here.
- Comment on I'm good, thanks 1 month ago:
- Not sure what this first point means. To describe decoherence you need something like density matrix notation or Liouville notation which is mathematically much more complicated. For example, a qubit’s state vector grows by 2^N, but if you represent it in Liouville notation then the vector grows by 4^N. It is far more mathematically complicated as a description. Your second point also agrees with me. We know the Born rule is real because we can observe real outcomes on measurement devices, something which MWI denies exists.
- This is also true in Copenhagen. Again, if that’s your criterion for locality then Copenhagen is also local.
- I think you should read Everett’s papers “‘Relative State’ Formulation of Quantum Mechanics” and “The Theory of the Universal Wave Function” to see the difference between wavefunctions defined in a relative sense vs a universal sense. You will encounter this with any paper on the topic. I’m a bit surprised you genuinely have never heard of the concept of the universal wavefunction yet are defending MWI?
- That quotation does not come one iota close to even having the air of giving the impression of loosely responding to what I wrote. You are not seriously engaging with what I wrote at all.
- Comment on I'm good, thanks 1 month ago:
The Many Worlds interpretation is rather unconvincing to me for many reasons.
|1| It claims it is “simpler” just by dropping the Born rule, but it is mathematically impossible to derive the Born rule from the Schrodinger equation alone. You must include some additional assumption to derive it, and so it ends up necessarily having to introduce an additional postulate at some point to derive the Born rule from. Its number of assumptions thus always equal that of any other interpretation but with additional mathematical complexity caused by the derivation.
|2| It claims to be “local” because there is no nonlocal wavefunction collapse. But the EPR paper already proves it’s mathematically impossible for something to match the predictions of quantum theory and be causally local if there are no hidden variables. This is obscured by the fact that MWI proponents like to claim the Born rule probabilities are a subjective illusion and not physically rule, but illusions still have a physical cause that need to be physically explained, and any explanation you give must reproduce Born rule probabilities, and thus must violate causal locality. Some MWI proponents try to get around this by redefining locality in terms of relativistic locality, but even Copenhagen is local in that sense, so you end up with no benefits over Copenhagen if you accept that redefinition.
|3| It relies on belief that there exists an additional mathematical entity Ψ as opposed to just ψ, but there exists no mathematical definition or derivation of this entity. Even Everett agreed that all the little ψ we work with in quantum theory are relative states, but then he proposes that there exists an absolute universal Ψ, but to me this makes about as much sense as claiming there exists a universal velocity in Galilean relativity. There is no way to combine relative velocities to give you a universal velocity, they are just fundamentally relative. Similarly, wavefunctions in quantum mechanics are fundamentally relative. A universal wavefunction does not meaningfully exist.
|4| You describe MWI as kind of a copying of the world into different branches where different observers see different outcomes of the experiment, but that is not what MWI actually claims. MWI claims the Born rule is a subjective illusion and all that exists is the Schrodinger equation, but the Schrodinger equation never branches. If, for example, a photon hits a beam splitter with a 50% chance of passing through and a 50% chance of being reflected and you have a detector on either side, the Schrodinger equation will never evolve into a state that looks anything like it having past through or it having been reflected. Indeed, even those probabilities I gave you come from the Born rule.
This was something Einstein pointed out in relation to atomic decay, that no matter how long you evolve the Schrodinger equation, it never evolves into a state that looks anything like decay vs non-decay. If the universe really is just the Schrodinger equation, you simply cannot say that it branches into two “worlds” where in one you see one outcome and in another you see a different outcome, because the Schrodinger equation never gives you that. You would have to claim that the entire world consists of a single evolving infinite-dimensional universal wavefunction that is nothing akin to anything we have ever observed before.
There is a good lecture below by Maudlin on this problem, that MWI presents a theory which has no connection to observable reality because nothing within the theory contains any observables.
www.youtube.com/watch?v=us7gbWWPUsA
Rovelli also comments on it:
The gigantic, universal ψ wave that contains all the possible worlds is like Hegel’s dark night in which all cows are black: it does not account, per se, for the phenomenological reality that we actually observe. In order to describe the phenomena that we observe, other mathematical elements are needed besides ψ: the individual variables, like X and P, that we use to describe the world. The Many Worlds interpretation does not explain them clearly. It is not enough to know the ψ wave and Schrödinger’s equation in order to define and use quantum theory: we need to specify an algebra of observables, otherwise we cannot calculate anything and there is no relation with the phenomena of our experience. The role of this algebra of observables, which is extremely clear in other interpretations, is not at all clear in the Many Worlds interpretation.— Carlo Rovelli, “Helgoland: Making Sense of the Quantum Revolution”
- Comment on What's it going to take to truly stop the US? 2 months ago:
Obvious answer is that the USA is the world’s largest economy while Russia is not, so if USA says “if you trade with Russia then you can’t trade with me” then most countries will happily accept ceasing trade with Russia to remain in the US market but if Russia says the same about the USA then people would just laugh and go trade with the USA.
The only country that might have some leverage in sanctioning the US is China but China has historically had a “no allies” policy. Chinese leadership hate the idea of that because then they would feel obligated to defend them and defending another country is viewed very poorly in Chinese politics. They thus only ever form trade relations and never alliances, meaning if your country is attacked they have no obligation to you. Chinese politicians may verbally condemn the attack but they won’t do anything like sanctions or even provide their own military support in return.
- Comment on a real danger of quantum computing 2 months ago:
Trying to think of classical models to explain the EPR paradox kinda misses the point of the EPR paradox, because the point of the EPR paradox is to assume that there is indeed nothing linking the two particles until you look to then show you that this leads to a contradiction with Einstein’s definition of locality.† You can indeed trivially think of classical explanations to explain the EPR paradox and how the +1 and -1 particles might be linked and predetermined, but that’s not the point of the EPR paper which is to explore what happens if we don’t make this assumption.
The paper that instead explores what happens if we do assume they are predetermined is Bell’s theorem, and Bell’s theorem is more complicated than just assuming that the particles are entangled and opposites such that one will be measured to be +1 and the other to be -1. Bell’s theorem shows that the behavior of the individual particle can be dependent upon the configuration of a collection of measurement devices, even if the particle only ever interacts with one measurement device in the collection. That not only violates Einstein’s definition of locality, but if you try to make it deterministic, it ends up violating special relativity as well.
The simplest demonstration of this is with three particles in the GHZ experiment. The point is, again, not merely that the particles have correlated values but that (1) those values are statistically dependent upon the configuration of the measurement device and (2) the values for an individual particle can be statistically dependent upon the configuration of a collection of measurement devices even if it never interacts with most of the devices in the collection.
† “Locality” is used in two different senses in the literature. One is relativistic locality which means nothing can travel faster than light. The other is what I like to call coordinate locality which is what Einstein had in mind with the EPR paper, which is the idea that things have to locally interact to become dependent upon one another. The EPR paper is a proof by contradiction that quantum mechanics without hidden variables violates coordinate locality specifically.
- Comment on a real danger of quantum computing 2 months ago:
In Copenhagen, “observing” really does just mean “observing” in the colloquial sense, there isn’t a fancy scientific meaning for it as the “collapse” is treated as a subjective update of knowledge and not a physical event.
- Comment on Anon tries to understand credit scores 2 months ago:
Banks aren’t that strict about super high credit scores. You can have a low score and they’d still give you a loan as long as it’s not absurdly low and you don’t have a bunch of other outstanding loans and you have an income. At least in my experience, my “credit” was basically one credit card I owned for a year and the bank still gave me a loan for a house. I would not bother to stress too much about the specific number. If your credit score is so low you won’t be able to secure a loan, you’d probably know without looking anyways. Just make sure you at least have one credit card because otherwise you might not have any credit at all which can make it hard to secure a loan.
- Comment on We wouldn't listen, anyway. 2 months ago:
You’re wrong. I’m a great ape and I can understand abstract language.
- Comment on Posting for the "Now guys he was MURDERED! Don't celebrate!" Crowd 6 months ago:
A double-standard is not inherently a bad thing. It’s a double-standard that we allow trained and licensed medical doctors to do operations on people but not bozos without any medical background, but one would have to be an imbecile to say this double-standard is a bad thing. It is indeed a double-standard to not show empathy to people who support industrial scale genocide to themselves be merked while believing we should show empathy to the victims and to people who do not advocate for such things when they die, but it is a good double-standard. It’s completely ridiculous to think we should be applying a single universal standard to everyone because people are not all the same.
- Comment on Posting for the "Now guys he was MURDERED! Don't celebrate!" Crowd 6 months ago:
Bullet-proof vest wouldn’t have saved him as he was sniped in the neck. The head is a moving target and harder to hit, which is why the less professional sniper missed Trump, he tried to shoot him in the head and Trump happened to move his head at that very second, and aiming for center of mass can be risky in case they are wearing something bullet proof. The neck is clearly exposed and more stable of a target than the head. The sniper knew what they were doing.
- Comment on Posting for the "Now guys he was MURDERED! Don't celebrate!" Crowd 6 months ago:
Literally right-wingers 24/7 are praising political violence, calling for the eradication of all Palestinians, glorifying the gunning down or running over of protestors, praising the murder of homeless people, praising the execution of minorities by cops, constantly glorifying the suicide rate of trans people, etc. Literally you can go on Twitter and find any of these right-wing accounts crying about how we shouldn’t glorify violence and read their post history and you will likely not even have to go back more than 1 day to find them glorifying violence.
- Comment on Posting for the "Now guys he was MURDERED! Don't celebrate!" Crowd 6 months ago:
I have seen so many right wingers post something along the lines of “leftists are so psychotic for being happy he was killed, we should kill all leftists in response!”
- Comment on observes your slit 6 months ago:
The interference pattern disappears if anything becomes entangled with the which-way information at all. 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.
- Comment on Too soon? 6 months ago:
It comes across to me as they simply lack empathy for other “kinds” of people. If you actually felt the same pain and empathy when watching the video of Kirk get merked, you should feel that a thousand times over when seeing a thousand videos of the IOF massacring children, many sniped in the same way Kirk got merked, and then you should look upon Kirk in disgust for supporting that and dehumanizing the Palestinian people. But the fact is these people don’t. They don’t see other “kinds” of people different from them as in fact “people.” Let’s be real, they don’t feel the same kind of empathy for Palestinian fathers dying as they do a white fascist dying. They constantly mock the deaths of minority groups like trans people. They suddenly have empathy and demand pacifism and valuing the sanctity of all life when a white fascist dies, but are silent in every other cas.e
- Comment on observes your slit 6 months ago:
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 classical state, (2) you look at it, (3) a miracle happens, (4) you perceive a quantum 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.
- Comment on A conundrum 6 months ago:
They are NOT looking to see if you are responsible with money. They are looking to see if they can make money off of you, so they want you to be a heavy credit user. Before I bought my house I made sure to take out two credit cards and just buy random shit on them for a few months because that boosts my credit score drastically which then made it easy to get the loan.
- Comment on Scientific unprogress... 6 months ago:
Periodic table is for atoms. I think you are mixing it up with the standard model, which is for subatomic particles.
- Comment on ISO 26300 6 months ago:
I would do my work in Open Office at home, save it to doc/docx, then when it is entirely completed, I will bring it to the library to load it in Word on a library computer and correct any formatting issues and resave it.