Earlier quoted context omitted.
Is superdeterminism even falsifiable?
Is Many-Worlds even falsifiable?
Hopefully this is on point https://www.lesswrong.com/posts/DFxoaWGEh9ndwtZhk/decoherenc...
Experiments spell doom for physical-collapse explanation of quantum weirdness
201–210 of 306 posts
Re: Experiments spell doom for physical-collapse explanation of quantum weirdness
#202Earlier quoted context omitted.
I don't see how relabelling "collapse" to "separation" and adding more or less infinitely proliferating universes solves the problem. MWI also contradicts itself. Supposedly the universes are independent, but if their influence doesn't define the wave equation they do nothing to help explain it. It's a very strong and exceptional claim with absolutely no evidence to support it. "Feeling" isn't enough.
> I don't see how relabelling "collapse" to "separation" and adding more or less infinitely proliferating universes solves the problem. MWI isn't just renaming the collapse. Copenhagen is fundamentally different in that exactly one outcome is somehow chosen / selected and all others cease to exist. In other words Copenhagen has to add / invent some information: Which world to pick and when to do so. MWI simply avoids…
> Copenhagen is fundamentally different in that exactly one outcome is somehow chosen / selected and all others cease to exist.
In MWI exactly one outcome / branch is somehow what we see and all others cease to exist to us. MWI just gives handwavy answers about how it is so.
Re: Experiments spell doom for physical-collapse explanation of quantum weirdness
#203Earlier quoted context omitted.
No. They don't behave at all like dark matter. Among other things, there's no reason for them to be distributed in a halo, nor for some galaxies to lack them.
Broad statements, do you have the time to elaborate?
The Milky Way and other similar galaxies look like spiral drawn in a thick 2D disk.
The dark matter halo looks like an invisible 3D ball around the thick 2D disk.
Something like https://www.google.com/search?q=dark+matter+halo&tbm=isch
Re: Experiments spell doom for physical-collapse explanation of quantum weirdness
#204Don't tell anyone, but in the back of my mind I wonder if what we call quantum mechanics has something to do with the rendering engine in this simulation we find ourselves in. Is quantum collapse just us "catching" the engine deciding what to render when we observe something? :-)
That's my interpretation as well, except I'd go a step further and say it's time-independent based on what we've seen of quantum entanglement. There's no reason to resolve a particle's state if it's not interacting with anything, but once you do you can safely define the entangled pair's state retroactively because it hasn't interacted with anything either.
So what we end up seeing is that after you measure one particle, the other behaves as if it always had the complementary value. It's not faster-than-light spooky action at a distance, it's more akin to reality "resolving" to a consistent time-independent state.
Re: Experiments spell doom for physical-collapse explanation of quantum weirdness
#205Earlier quoted context omitted.
If you have only one particle of the entangled pair, you can't do any experiment to check if they pair is still entangled or someone else has done something to the other particle and broke the entanglement. Someone else is not necessarily a person. May be a device or just a brick. In a common case, when you measure your particle you get 50% "yes" and 50% "no". So if you have a stream of particles that are one half of…
Dang I low key have a problem here because I already mentioned it was a joke and gave the same explanation, but because this is the top reply and the comments both show n-hours ago it looks like I walked back my statement in response, and I think it's fair to say that this is why the original comment got a down vote and ended up at the bottom.
After reading your comment again, now I'm wondering how does the variation of QM discussed in the article handle the special cases you mentioned.
In the usual QM the explanation is "easy" because the collapse is magical.
But if they want to eliminate the magic and propose a underlying "physical" process for the collapse then they have nasty problems and FTL transmission.
Re: Experiments spell doom for physical-collapse explanation of quantum weirdness
#206Earlier quoted context omitted.
No I don't think so. Many worlds is basically the hypothesis that we can put arbitrarily large systems in superposition. Like schroedingers cat that is both dead and alive, but instead it could be the whole lab, the whole planet, the whole galaxy that is simultaneously in two different states. We could test this by trying to actually do it, by putting really large and complex systems in superposition. If they both ev…
> We could test this by trying to actually do it, by putting really large and complex systems in superposition. Is there any hope that one could actually do this? The article mentions that large systems may be self-observing (via gravity).
I thought there's a quasi-classical approximation of quantum gravity, it doesn't work only for event horizon due to infinities there, but should work fine for diffuse matter, like how most calculations for electron orbitals use classical electromagnetic field.
Re: Experiments spell doom for physical-collapse explanation of quantum weirdness
#207Earlier quoted context omitted.
What I don't understand is why we call it "observation" when it should really be "interaction". The quantum weirdness resulting from the collapse of probabilities has nothing to do with a conscious observer, just whether and at what point the phenomena in question interact with something else in an observable way.
Because when an object "interacts" with another object, it goes into a quantum superposition with that object. It is only when we observe that we don't see the superposition. The obvious implication that people don't like to talk about is that there is nothing special about observation, it is just that our own body goes into superposition and we only subjectively experience one of the quantum states.
> there is nothing special about observation [...] we only subjectively experience one of the quantum states
That subjective experience seem something special!
There is nothing special about quantum superpositions - they are pure quantum states like any other. They are superpositions when we consider them in a particular basis. How does the subjective experience project your body - and the rest of the universe - onto one element of the right basis?
Re: Experiments spell doom for physical-collapse explanation of quantum weirdness
#208There is an often-repeated statement that different quantum mechanical theories are equivalent. This is an over-simplification. Is wave function collapse is a real thing or just an approximation of what happens when a large system is entangled? Some smart people have tried to make theories where wave function collapse is a real thing. These new experiments are working to rule out those ideas. My feeling is that Evere…
I don't see how relabelling "collapse" to "separation" and adding more or less infinitely proliferating universes solves the problem. MWI also contradicts itself. Supposedly the universes are independent, but if their influence doesn't define the wave equation they do nothing to help explain it. It's a very strong and exceptional claim with absolutely no evidence to support it. "Feeling" isn't enough.
It's not just a relabelling. In collapse theories, the wavefunction stops obeying the Schrodinger equation for a moment and discontinuously jumps to a new state. The times when it performs a discontinuous jump are called "measurements", though this doesn't necessarily mean there's a scientist sitting there with a ruler, it just means that the system has interacted with its environment sufficiently. In the many worlds theory on the other hand, the wavefunction continues to obey the Schrodinger equation for all time, and the natural result of this is that the wavefunction becomes very complicated and entangled, so that the motion of atoms here on Earth is very entangled with photons heading away from us at the speed of light out into deep space, along with pretty much everything else. But there's no mention of "separation" or "worlds" in the basic description of the theory; the one sentence description of many worlds is "the wavefunction obeys the Schrodinger equation all the time with no exceptions".
Where the worlds come in is that it's impossible to do calculations on the wavefunction of the entire universe, so we need to come up with a way of dividing it up into manageable pieces. Not because the theory requires that it be divided into pieces, but because otherwise we couldn't handle the math. The worlds are one of the ways we do that: We break the wavefunction of the universe into approximately perpendicular components that don't interfere with each other very much and don't have too much entanglement making them hard to understand, and we call those worlds. We can further simplify things by just looking at a subsystem of the universe rather than the entire universe, which involves taking a partial trace (this tends to introduce randomness). As time goes on and entropy increases, the entanglement and complexity even within a "world" will continue to increase and at a certain point we may notice, "hey, this component is really complicated now, and it can itself be divided into subcomponents that are approximately orthogonal and don't really interact with each other much, I can simplify my calculations by treating those as separate worlds now". This is what we mean when we say that worlds tend to split apart, but since the worlds are only approximately orthogonal and independent, when you define splitting is really a matter of how much error you're willing to allow in your calculations. (Also, the process of splitting is driven by increasing entropy, so when (if?) the universe reaches a point of total heat death and entropy stops increasing, this will also imply that the worlds have stopped splitting.)
So I'm not sure what you mean by "strong and exceptional". It's just math, and can be compared with experiment just like any other piece of physics. Take the experiments done in the original article. If any kind of collapse had been observed, then that would have straight-up falsified the many worlds theory. Many worlds says that physical systems can become entangled with their environments, but their wavefunctions can never just collapse, and these two cases are distinguishable in a careful experiment. Since collapse wasn't observed when these tests were done, that provides a little bit of evidence in favour of many worlds.
Falsifiability is a little more complicated for collapse theories. People don't agree on the exact definition of a "measurement", and what level of interaction with the environment is required to trigger a collapse, but in order to have a falsifiable theory, it's important that we have a precise, mathematical definition of when a collapse should happen (this definition does not have to be deterministic, it could just give us a probability distribution). So various people have put forward different definitions, and it sounds like these experiments have ruled out a bunch of them, but obviously they haven't ruled out every collapse theory put forwards by every physicist ever. It's a bit like when the LCH failed to find any supersymmetry particles, and some physicists were like, "okay, but in my version of supersymmetry, the particles are heavier than the energies reachable by the LHC so of course we wouldn't expect to have seen them".
Re: Experiments spell doom for physical-collapse explanation of quantum weirdness
#209Earlier quoted context omitted.
> I don't see how relabelling "collapse" to "separation" and adding more or less infinitely proliferating universes solves the problem. MWI isn't just renaming the collapse. Copenhagen is fundamentally different in that exactly one outcome is somehow chosen / selected and all others cease to exist. In other words Copenhagen has to add / invent some information: Which world to pick and when to do so. MWI simply avoids…
> Copenhagen is fundamentally different in that exactly one outcome is somehow chosen / selected and all others cease to exist. In MWI exactly one outcome / branch is somehow what we see and all others cease to exist to us. MWI just gives handwavy answers about how it is so.
It follows by contradiction of the opposite statement: Lets say that all "you"s across all branches perceive all the other branches as well. That means that they do influence each other. In other words they are not separated and never where different outcomes to begin with.
But, all the interpretations of quantum mechanics start with the axiomatic assumption that the universe is modal and that there are different possibilities / outcomes. They only differ in if they chose to turn hypothetical outcomes into real outcomes or simply let everything be equally real from the get-go.
And yes, even superdeterminism has to deal with / model hypothetical outcomes. It just says that some of them cancel out each other early on as they would lead to inconsistencies in the future otherwise.
Re: Experiments spell doom for physical-collapse explanation of quantum weirdness
#210Earlier quoted context omitted.
Not the parent, but I 'd say this amounts to how you define a "universe". There is a single wavefunction which says that one "copy" of you observes result A and another "copy" observes result B. Using the phrase "many universes" implies that these two scenarios are considered as "different universes". I personally do not like this phrase and find it misleading.
You are all the "copies", and, under certain conditions, can experience all their observations. Think of yourself more as an aspect of a multifaceted being experiencing the universe through you.
> under certain conditions, can experience all their observations
What conditions are these?