Experiments spell doom for physical-collapse explanation of quantum weirdness
quantamagazine.org
quantamagazine.org
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 Everett's "many worlds" interpretation is the clear favorite: there is no wave function collapse.
Because we live in the macro world, it feels like a single unitary reality is simpler, but actually, the MWI makes fewer assumptions. So I would turn that around and put the burden on the other theories to show that collapse is real, the default position should be MWI.
>The many-worlds interpretation implies that there are most likely an uncountably infinite number of universes.
The MWI says that there is one single universal wave function, which evolves in time by unitary evolution forever, and that that universal wave function is all that exists. That is one universe, not an infinity of them. It is just one universe that is nothing like what we think we perceive.
Wanna join? You can be number 2 thus have second dibs at the buffet.
What conditions are these?
Getting to that point can take several years. A quicker option seem to be drugs, based on conversations I had with friends, but I never wanted to artificially taint my perception, so I did it the hard way. My findings are that while there is no fate, there exist enough aspects in universes similar enough to yours, but perhaps chronically shifted, that you can learn from their mistakes. This is known as instinct, "guardian angels", premonition, deja-vue, etc. Good luck.
If you could travel between these many earths, you could even end up in one - let's call this mythical land "Australia" - where South was up!
Sounds a bit crazy but some people believe it could really exist.
The collapse amounts to just setting some terms to zero.
This is especially problematic because QM doesn't predict any particular decomposition of a quantum state into particular classical states. That is, the Schrodinger equation doesn't actually predict that a particle has some amplitude here and some other amplitude there, as is often presented; instead, it predicts that it is described by some vector which can be decomposed in many different ways. You can say it has some amplitude X here and some amplitude Y there, but with any 2 points in space-time (adjusting the amplitudes). Or, it can have some combination of position and spin with amplitude X, and some other combination of position and spin with amplitude Y. You can choose any basis you like for the measurement, and you will get the corresponding answer.
But, for MWI to actually predict experimental results (and the classical world we live in) you not only have to choose to look at a single element of that basis, but you also have to believe that the classical basis is somehow preferred.
It does predict it, this decomposition is called decoherence, where a classical state splits into a superposition of several different classical states.
No, that's not what decoherence is. Decoherence is the spread of entanglement over a very large number of untrackable degrees of freedom (usually referred to as the "environment"). This makes interference effects unobservable. But decoherence itself does not involve any "splitting"; the entanglement that decoherence spreads over a very large number of untrackable degrees of freedom has to already be there before decoherence can act on it.
And yes, spread of entanglement does mean splitting. Entangled state is not factorizable, because all states in it are split. This splitting is the result of splitting of the initial state.
No. The 100 atoms is the largest molecule that we can do experiments on without having decoherence happen and ruining our attempts to observe interference.
The number of degrees of freedom in the environment is many orders of magnitude larger, something like 10^30 or more for a typical experiment.
Title article is literally about trying to test those theories experimentally.
Here's the best poem ever written, or that will ever be written:
Roses are red
Violets are blue
MWI stinks
And so do you.
I hereby accept my position as God Poet of the Universe.
The MWI is a simpler theory than other interpretations because it does not require "collapse" to be a physical process. The "realness" of the other worlds is untestable, but also not part of the theory.
"unreal" MWI should be the null hypothesis given what we know to be true about quantum mechanics. If we find evidence that collapse is a physical process then we can reject it, but otherwise it makes the fewest leaps. At the moment the Copenhagen intepretation is taught instead, which is a problem. To quote wikipedia:
> There is no uniquely definitive statement of the Copenhagen interpretation
And
> the device used to observe a system must be described in classical language, while the system under observation is treated in quantum terms
In other words, it does allow you to predict the result of an experiment, but we know it can't be right because it's impossible to formalize without building this "classical observer" into the model. Attempting to build on this inevitably leads to metaphysical nonsense about consciousness.
In "unreal" MWI there is a universal wave function, and something is "real" to us if it is entangled with us. The "many worlds" terminology makes it easier to visualize but doesn't mean those other worlds are real because whether something is real is subjective in this interpretation. Subjective reality may be a problem for some people, but if you look at the evolution of physical theories, we consistently find that everything is more subjective than we thought it was (see also: relativity).
By making quantum computer, we are making us into Schrödinger’s Cat. Which entangles our destiny to a quantum possibility.
Such as a highly sophiscated military quantum computer which decides war and peace on quantum computing.
It must be very fun to observe us from a Alien Species's angle.
But what are the worlds?
My feeling is that Max Tegmark has it right. Everything is mathematics.
I wish I understood it better.
Me too but... It would still be some form of mathematics as soon as you tried to write it down in a neat, precise way for others to understand it. Maybe exotic math, but still math :p
Saying that sure, they evolve like ours, and sure they affect ours, but even so they are not real - that is I suppose one stance, but then you are getting pretty close to solipsism.
No, you'd get something like Bohmian mechanics, or Rovelli's relational interpretation. Which is my point: you can only take this as evidence of other worlds if you basically smuggle those assumptions in.
Is there any hope that one could actually do this? The article mentions that large systems may be self-observing (via gravity).
One location in the latent space of a latent diffusion model is a view into a universe that is as real as ours. That half cat, half dog monstrosity you accidentally created. It exists as a drawing, or as a physical mass of flesh, with every possible back story as to how it got there. And also every possible future.
edit- brain fart
Such confidence ... I envy that.
You're right though, I very much doubt QFT as it stands is the bottom. However, that doesn't mean the current debate is stupid. Whatever underlies QM, you'd still expect the measurement effect to also be an emergent property. The debate about whether atoms existed is still meaningful even though we now know that "atom" isn't a perfectly natural category. Indeed there are protons and such underling the physics, but the protons do pretend to be atoms much of the time, and thus pretend to do all the things we use atoms to predict.
Similarly, MWI and collapse (as well as, if less so, weirder theories) can be good explanations as to why a quantum phenomenon occurs even if there's also a reason they happen.
lol
Until we find philosophically or experimentally distinguished ways to pare down its ontological cost, working with most general theory is just keeping an open mind.
It is a sign of the much greater maturity of the physical collapse models that their parameters can be constrained by experiment. The ability to be constrained is a good sign, not a bad one.
I love John Preskill’s standard nod to superdeterminism in his writings: without mentioning it by name he says “I leave it up to the reader to decide how seriously to take this possibility” (get it?)
https://news.ycombinator.com/item?id=33223391
The idea is that the natural laws are fractal, which when mapped out trace many state space configurations. But with a fractal there are always gaps in state space that remain no matter how much you zoom in or out; fractals preserve certain structural invariants at all scales.
So the idea is that counterfactual reasoning sometimes fails in a fractal universe, because statistical independence no longer works as a general rule (your counterfactual could lie in one of those gaps). He first published this idea in 2009 under the name "invariant set postulate":
https://en.wikipedia.org/wiki/Invariant_set_postulate
His paper with Hossenfelder is also a good overview:
https://www.frontiersin.org/articles/10.3389/fphy.2020.00139...
Superdeterminism gets an unnecessarily bad rap.
If determinism is true, don't you mean "necessarily"? :)
Yes. That is a big reason why most physicists do not favor superdeterminism.
The game of life is perhaps a nice analogy here. On the 2d grid of the game of life, a glider seems moving in a certain direction when time moves forward. But in the 3d grid, where time is the third dimension, a glider is just a static volume of space.
The reason we experience time is that the evolution of the block universe does depend on the dimension you look at (e.g entropy generally increases in the positive time dimension), and because our consciousness is an emergent property of a self-sustaining structure within the block universe, it's plausible at least that we perceive movement in time different from movement in space. I realize this is very sloppy wording but I'm having trouble finding better words to describe my intuition here.
That's one way of interpreting it, but superdeterminism does not entail or require this. Superdeterminism can be formulated just fine for a universe that evolves in time from some initial state according to causal processes.
It’s not violated - it simply doesn’t apply because it’s predetermined that the measurements that are done work well together. The experimenters follow the script.
If you could refine what these words all mean, I guess we could understand it as something more than "Deutsch seems to think that yes", which can replace your sentence entirely, "yes" describing it all as precisely.
I am myself, in some ways, a general intelligence running on a quantum computer but I dont feel like I can observe myself existing in a novel special way. Let alone being able to then express it for you in a way that is novel as well.
And while you are indeed a general intelligence, I don’t think you’re running on a quantum computer.
If many-worlds is true, we are already observing ourselves in each of those universes in which we can observe, we just don't communicate with our replicas. And if the AGI can communicate with its other instances, the exponential replicas will quickly overload their channel.
I request further elaboration here, please. Examples would be great.
> than the fact that logic is not falsifiable
What?
Also, many worlds interpretation as it currently exists is already falsified by its incompatibility with gravitational nonlinearity.
"True" free will is ruled out by all existing physical theories, so that's not why it's controversial. The bigger problem with superdeterminism is that it wants to explain physics without assuming statistical independence, even for far away events.
“Proposed” - but as something that avoids the issue but it’s not worthy of much consideration.
- I was going to ask whether it is still possible to maintain, in the light of experimental experience, the idea of a deterministic universe?
You know, one of the ways of understanding this business is to say that the world is super-deterministic. That not only is inanimate nature deterministic, but we, the experimenters who imagine we can choose to do one experiment rather than another, are also determined. If so, the difficulty which this experimental result creates disappears.
- Free will is an illusion - that gets us out of the crisis, does it?
That's correct. In the analysis it is assumed that free will is genuine, and as a result of that one finds that the intervention of the experimenter at one point has to have consequences at a remote point, in a way that influences restricted by the finite velocity of light would not permit. If the experimenter is not free to make this intervention, if that also is determined in advance, the difficulty disappears.Uhh, no. Essentially all existing physical theories are devastating for any non-compatabilist account of free will.
The point, that many ignore, however is that, free will does not matter. It is irrelevant. Regardless of whether one has free will or not, one still has to make choices and support the consequences of said choices. Lack of free will was never the get out of jail free card some fear it to be.
If you bring in to the discussion sociology and psychology, free will makes even less sense.
That being said, in her latest book she has a pretty strong argument against free will that does not require superdeterminisim so if that sounds interesting check it out.
E.g., I am in some universe taking every possible action right now, but I'm only experiencing the actions which I "chose" to take.
Furthermore it still removes any actual willed choice of path within the context of our existence. I am not some meta-entity seeing all possible paths and choosing one for some unknown reason. That would be an existential alien "haunting" me and not "free will".
(Of course, you could also just say the feeling is an illusion.)
I don't know if you can ever answer it one way or the other, because while consciousness certainly exists (again a fact I believe just because I feel it), it can't in any way influence the universe, at least per current theories of physics.
On the other hand, if you're right that many-worlds is real and our consciousness persists in all of them, then we will, individually, come to realize that is the case, as find ourselves still alive, forever, ever more improbably (since, I think, the odds of dying would never be 1, so you'll always be alive in some lucky world).
I believe someone called that idea "quantum immortality" and I find it conceptually interesting if not somewhat terrifying. However it does seem like the inevitable conclusion of these ideas.
I'm not sure I'm following the argument. Let me phrase it this way: can you devise an experiment which will determine if a given entity is conscious?
> I believe someone called that idea "quantum immortality"
(Thanks for the term; I'd heared the idea expressed before, but not that phrase.)
Skimming the wikipedia page, I didn't find any of the counter-arguments to be particularly compelling.
So, while I'm not sure how deeply I believe it (simply because it feels very unintuitive -- and I'm definitely not about to try to kill myself to test it!†), I agree with you: it really does seem like the inevitable conclusion of these ideas; I also agree it's somewhat terrifying!
Especially when you consider that as time goes on, probably in the majority of the universes where you are alive, you are just barely alive, in great pain. The only consolation is that, perhaps, you'll still have enough awareness to think to yourself, "incredible that I haven't died yet -- I guess many-worlds really is true!"
(† Even if you are knock-down 100% convinced in quantum immortality, you probably still don't want to engage in wildly risky behavior or try to kill yourself -- because you will be killing yourself in a large number of universes, and causing a lot of pain to your loved ones in those universes. A similar argument could be applied to engaging in any sneaky behavior which would cause significant pain if discovered.)
No, without being able to define what consciousness is we can't make an experiment to test for it. The simplest explanation in my view is that qualia are a base "element" of the universe and information systems and our consciousness is a loosely drawn subset of qualia associated with our brain/body's information system. To be clear this is not dualism, the qualia are not some magical thing riding on top of physics and cannot change the path of particles from their physically determined routes.
Regarding quantum immortality I don't know if it necessarily demands a universe in which some form of every person lives forever by some unexpected chance of quantum improbability. At least in terms of a continuity of normal life it may be that the probability of a person living longer than a human body physically can is zero. However some have argued there is a non-zero chance that random quantum fluctuations could lead to brief instances of a person arising from "nothingness" anywhere and anytime in the universe, and some of those persons could by pure luck happen to match the mind of a person elsewhere. However this does start getting into the realm of silliness and quantum randomness and infinite universes allowing for literally every possible combination of particles.
Yeah, intuitively somehow it seems absurd to think that "everything possible is happening", somewhere, in some dimension. It almost feels like a modern version of Zenos paradox. Like, in the limit, there are no universes in which you're alive...
You can derive if from the MWI. We already know that the "worlds" separate and almost completely cease interacting. The interactions decrease to the order of "two to the power of Avogadro's number" almost immediately. The collapse interpretation rounds that to zero (at some arbitrary point).
To make that more concrete you have to add a term to the equations, making it theoretically testable, but it's remarkable that anybody could manage to test it in practice. It's clever to use a neutrino detector -- something designed to measure ludicrously small amounts of interactions.
I don't think anybody is surprised by the results, just that they could get any. The un-physical arbitrariness of the cutoff caused problems from the get-go.
I was going to say that it doesn't make MWI any more palatable, though I suppose it does. They've detected the other branches, albeit in a very indirect way. They're real. But they're just as inaccessible as they ever were.
You still need the concept of decoherence to make it work. The unstable equilibrium can't hold for large objects. That's both mathematically and physically sound.
Not as an actual physical process, no. "Collapse" in the MWI just means that, once the "worlds" have decohered, within each "world" the wave function can be collapsed to the one that describes the measurement result observed in that "world", for purposes of predicting future results. But in the MWI this is just a mathematical convenience and doesn't correspond to anything physically happening.
In the theories being tested by the experiments described in this article, though, collapse is an actual physical process: there is only one "world". This contradicts the MWI.
> They've detected the other branches, albeit in a very indirect way.
What experiments are you referring to here?
It corresponds to the inner product of the two branches of the wavefunction going to 0 due to physical phenomenon.
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
(edit: to answer my own question, the rabbit hole starts here: https://physics.stackexchange.com/questions/485214/ -- basically, accretion happens because light matter can radiate and shed its (kinetic) energy that way. Dark matter does not radiate so it remains in a higher-energy state)
This was one of the more eye-catching statements in this thread. To be blunt, you're wrong. A straightforward and almost inevitable dynamical explanation has been available (and explored in ever greater detail) since at least the mid-1990s, driven in part by the Saskatoon experiment and subsequently supported by BOOMERanG's observation of the first acoustic peak, and many others lines of evidence since then (see [1] for a less-heavy explanation than what follows).
You may wish to check this chapter from a forthcoming graduate-level textbook in galactic dynamics from well-known galactic astrophysicist Jo Bovy <http://astro.utoronto.ca/~bovy/>, which you can read for free at his site: <https://galaxiesbook.org/chapters/IV-01.-Formation-DM-Halos....>.
There are of course other already-completed textbooks. For example, one can find an excellent pedagogic (if advanced) treatment of primordial Gaussian Random Fields[2] as applied to halo formation in chapter 7 of Mo, van den Bosch & White (2010) <https://www.cambridge.org/core/books/abs/galaxy-formation-an...> (you can find the chapter on scy hob via its DOI if you don't have institutional or otherwise affordable access).
- --
[1] https://lweb.cfa.harvard.edu/~deisenst/acousticpeak/acoustic... from <https://astronomy.fas.harvard.edu/people/daniel-eisenstein>
[2] If you're more visually inclined and can't find the illustrated version of Mo et al., see the diagrams on p.3-5 of this slide deck on GRFs <https://www.astro.rug.nl/~weygaert/tim1publication/lss2016/l...> from Rien van de Weijgaert of the Kapteyn Institute at the University of Groningen.
“What actually happens in an experiment with electrons is kind of interesting. Since photons are massless they are easy to excite if they have long wavelength and hence low energy. Whenever an electron gets accelerated many "soft" (i.e., long wavelength) photons get emitted. But if the acceleration is weak, the photons have such long wavelength that they provide little information concerning which path, and interference is possible.
It is the same with gravitons. Except the probability of emitting a "hard" graviton (with short enough wavelength to distinguish the paths) is far, far smaller than for photons, and therefore gravitational decoherence is extremely weak.”
So you’re saying… theres a chance…? :)
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.
Given the equations that describe quantum mechanics (ie Schrodinger equation) MWI is essentially the "null hypothesis". No equations that describe collapse have ever passed the rigor of experiment and all collapse theories require modifications to the mathematics of QM. The burden of proof here is on theorists that support collapse theories not proponents of MWI.
Null hypothesis in the sense of not producing any predicition? /joking
I agree with the grand-parent that substituting a "collapse" that we cannot understand with a "separation" that we cannot understand doesn't seem a big step forward.
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 having to pick by continuing every branch simultaneously and recursively.
Meaning that MWI is actually a simpler theory and shows that the selection is unnecessary and all problems that come with it can be avoided. In that sense, the burden of proof lies with Copenhagen IMO and it just gives handwavy answers that the selection process somehow involves a conscious observer, whatever that is ...
> 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.
In MWI the wave function IS the integral of all possible outcomes / worlds / branches. In that sense they don't just influence it, they define it. Not sure how that is contradictory.
Btw, the same goes for Copenhagen in the state of super position as well. So, they are identical up to the point where Copenhagen selects one (collapses) and MWI simply carries on.
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.
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.
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".
Separation that you are talking about boils down to different parts of wave function being uncorrelated with each other. If this is the case, then events in one "universe" can't have causal connection with another because that would imply correlation.
Worse than that, I'd say that "physical collapse" is usually presented to the general public as established scientific fact, even by prominent scientists that know better.
I've listened to enough Carroll to convince myself that I think MWI makes sense, but what I never got is that it doesn't seem to offer much in terms of explanation of how the entangled state ends up being what it is: We see a particular result of an experiment with many possible a priori outcomes, but is there a mechanism that determines which particular entangled state we end up in? Something like the phases of the wave functions on individual Hilbert space sectors conspiring to produce a certain outcome, so that an omnipotent observer with full access to both parts would be able to tell what happens a priori, no dice being rolled? Or is that just hidden variable theory?
According to MWI, all possible results of an experiment are manifest and real. You're asking "which particular entangled state we end up in?". You end up in all of them. For a 2-state superposition system, there are 2 versions of "you" that exist after the experiment, both of which are equally real. Subsequent measurements of the quantum system will appear to be "collapsed" for both versions of you but each will see different and opposing values.
Except that I've only ever experienced ending up in one of them, so exactly how did the "I" that is typing this right now wind up here, and not in some other branch?
There's an unexplained bifurcation of consciousness implied by MWI which it cannot explain (although I think it suggests the appeal of MWI since it gives enough wiggle room that people think that their free will could control which universe they wind up in, which appeals to everyone's inner Malcolm Gladwell).
Maybe your copy in another branch even posted the same comment.
Both are worthwhile if you like thinking about these kinds of things.
I've generally found nearly zero people who have read those books and of them most people poo-poo it all, and don't really engage with some of the issues presented in them.
He may be wrong. Einstein was also wrong about the EPR paper. But it seems like he's trying to engage with the problems and do science rather than just provide philosophical justification.
I don't see how that would allow or require seeing a cat in a complex linear superposition. You just have one set of frames which describe a live cat and another set of frames that describe a dead cat.
For simplicity, let’s say that all quantum interactions have two possible outcomes, 0 or 1.
The first point is that we can only talk about what interactions appear to have done in the past in our worldline/universe, which is randomly distribute themselves between 0 and 1. If we happened to be on a worldline where all interactions had always resulted in 0 for the whole history of the universe then that universe almost certainly wouldn’t support complex life. So perhaps there’s an observership bias here: if quantum interactions hadn’t decently distributed themselves between 0 and 1 then we wouldn’t be asking this question (just like the values of all the other fundamental constants).
As far as I can tell there’s nothing in current theories which would rule out all future interactions happening to result in a 0. Let’s hope our consciousness don’t end up on that worldline (unless you believe in quantum invulnerability).
Aa a function is a mathematical abstraction, I don't see how it could be real... unless you believe the world is made of math..
Everyone agree about the math, but there are a few interpretations of quantum mechanics. All are weird and equivalente, so it's not possible to make an experiment to decide which one is the correct one.
There are a few attempt like this to extend QM and get a less weird theory, but it looks like this failed, at least with the more simple model for the extension. Anyway, most people just use "Shut up and calculate".
EDIT: I misread the article, I thought it was about whether collapse occurs in general, not about physical explanations for collapse
> The experiments find no evidence of the effects predicted by at least the simplest varieties of these collapse models.
Is quantum collapse just us "catching" the engine deciding what to render when we observe something? :-)
Nb. quantum also highlights assumptions made by our brain's rendering engine.
In forward raytracing, images are rendered by "shooting" photons from all lightsources and seeing which ones end up hitting the player's camera. This is similar to what we think happens in nature, but the calculation is extremely inefficient, because the vast majority of photons never hit the player's viewpoint.
In backward raytracing, we only shoot "photons" backwards from the player's camera, and see which rays end up hitting a light source. This computation is much more efficient.
It makes me wonder if our "simulation" uses a similar shortcut
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.
It's incredible how influential Penrose has been for such a long time, and continues to be. As far as I can tell (I'm interested but far from an expert) very few theorists are coming up with genuinely testable ideas in this area.
A few QM experiments:
https://en.wikipedia.org/wiki/Double-slit_experiment
Little dots on the screen are some collision with a macroscopic visible effect.
https://en.wikipedia.org/wiki/Stern%E2%80%93Gerlach_experime...
Silver atoms going one way or another again on a screen and little dots.
https://en.wikipedia.org/wiki/Aspect%27s_experiment
Detectors probably some collision again and counting or imaging apparatus.
And of course a collision is a physically mostly discrete event so no one would question wether there's a need for an "observer" for it.
Would love to be pointed at some QM where there's no collision or similar discrete event for "measurement" as I'm a total noob in QM :).
this article is credulous -- yes, this may exist and semi-serious people are looking for it, but pls don't confuse 'we haven't found it yet' with 'current science suggests this is very small'.
how small?! at least admit that your theory doesn't predict an energy level. 'Current science suggests that bigfoot dwells in the places we have not yet looked'. Also put the newest paper in the first paragraph, don't make me dig through recirc links, ugh.
1. https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.12...
To a non-expert it can be difficult to separate which theories lay on solid ground and which theories are highly speculative.
> To a non-expert it can be difficult to separate which theories lay on solid ground and which theories are highly speculative.
Sure, but isn't that the point of doing these experiments?
Based on the other responses, it seems like we can mathematically model these phenomena very well and make very good predictions. However, when it comes to explaining why these phenomena exist in the first place, we are like a medieval doctor trying to explain why antibiotics work.
It would be like accidentally discovering antibiotics during the plague. You might not know how it works or why, but you know what it does and it absolutely gets the job done.
So... not really like how our past misunderstanding of disease, which was useless as well as being wrong.
So QM itself is on very, very solid ground. You're using it now on your computer.
The interpretations of QM and the attempts to reconcile the exceptionally well tested mathematics of QM and the reality that we experience which is not-QM at all are all philosophical with zero evidence. Everyone just tries to make compelling arguments based on things like Occam's razor about why their horse is the best one in the race without actually knowing anything at all.
We have place a few bounds around things like Bell's inequality so we know that local hidden variable theories are ruled out, but that is about it.
The title article is very interesting because its one of the first few actual tests to probe if there really is a transition between QM reality and classical reality. Regardless of who actually wins the horse-race the important thing here is that there's slow progress being made on trying to experimentally test theories. This is why I've always liked the Penrose models of collapse better than the MWI models since the former have some chance of being actually testable, while with MWI you just blindly decide it is true or not and then you argue a bunch about philosophy and never do any experiments, which isn't science. Penrose models of collapse might be wrong but at least they're in principle testable, which is incredibly exciting about this article.
“We” in the collective sense are not clueless about quantum mechanics at all. We have an extremely exact model, and pretty much every attempt At proving that it’s insufficient fails. The only “problem” with quantum mechanics is the same as the “problem” we had in Newtonian mechanics when we found that a tennis ball and a bowling ball falling from head height hit the ground at the same time. This was a problem because intuition would have the heavier object fall faster than the lighter. It wasn’t an actual problem with Newtonian mechanics though mind you. Our intuition was counter to reality, the problem was the intuition not the model of reality.
Naturally there were other actual problems with Newtonian mechanics, but none of that had to do with making it more intuitive. And the same is true of quantum mechanics. It doesn’t sound intuitive to most people, but that’s not problem, it just means your intuition about how systems should behave at these scales is wrong.
> In 1996, Qijia Fu of Hamilton College in New York — then just an undergraduate — proposed using germanium-based neutrino experiments to detect a CSL signature of X-ray emission. (Weeks after he submitted his paper, he was struck by lightning on a hiking trip in Utah and killed.)
Clearly left a mark on my memory.
Only it was not aliens but Universe (Sub)conscious - Homeostasis
This makes eminent sense to me.
I have a notion that I'll try to present in its simplest form which is that a quantum system exists in background 'sea' or 'substrate' akin to random noise whose maximum fluctuations are of themselves insufficient to disturb or perturb said quantum system.
Without this noise an 'event' such as a particle, photon etc. would perturb the quantum system in a predictable way thus it would 'collapse' into a predictable outcome (according to understood physics).
As the noisy substrate permeates and superimposes on everything it randomizes the 'collapse'. Of course, we'd have to invoke notions such as virtual particles zero point energy, Casimir-like effects—even then, saying that is a gross oversimplification without much additional amplification. Perhaps it's best just to say that essentially a noisy fluctuating background environment would perturb and randomize an otherwise predictable quantum system.
Again, like many of these theories, I've little to support my idea except intuition—and with quantum mechanics relying on it is a very dangerous thing to do.
* No physical collapse => Everett interpretation AKA "many worlds"
* Many worlds gives us the Anthropic Principle for free
* The Anthropic Principle explains the origin of the first living organism, or, to put it another way, the observed existence of the origin of our first living ancestor does _not_ set any lower bound on the probability of the first living organism developing from non-living molecules.
* A very low probability of the origin of life implies the non-existence of any other life in the observable universe.
* Therefore, no aliens.
(The aliens do of course exist in other parts of the total Universal Wave Function, but we never get to meet them.)
This reminds me of how our own heart's peacemaker works.
There are plenty of "infinitely fast" synchronization effects like this..some perhaps less obvious than others, but many pretty pedestrian and accessible to lay people. Neither the junction of a scissors or the "spot light" on clouds need be constrained by light speed, for example. People routinely abuse "nothing" (or maybe "go") in the " 'nothing' can 'go' faster than light" saying. :-)
That was already part of von Neumann’s model of measurement over 90 years ago.
I should perhaps have used the word "entanglement" rather than "intrication". Oops.
Quantum systems measuring other quantum systems is part & parcel of quantum computation. So that can lead to more clear thinking on (some of) these matters.
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 an entangled pair, you just get a random sequence.
It doesn't matter if the other half is still flying happily in vacuum, got into a detector like the one you have, or it just hit a wall. You just get a random sequence. Otherwise, it could be used to build a FTL "walkie talkie".
If you later can talk with someone in the other side that measured the other half of the pairs, then both of you can compare notes and notice that the two random sequences are equal or oposite or something in between according to which experiment each of you have done.
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.
Other models are useful in other contexts.
Reality is unknownable. But we can always use better models.
I really appreciate this forum - as it is one of the last places that I know of where one can have a civil discussion - and therefore I will take the effort to show that pure quantum mechanics - with no additions - essentially explains the process of measurement which is not at all sudden as the name "collapse" would suggest. The reasoning comes from von Neumann himself, but now sometimes it's attributed also to Wojciech Żurek.
TLDR of below: All processes in nature, including the measuring process are unitary, the "collapse" is just an artifact of our ignorance about the exact state of the measuring aparatus. Here it goes:
For simplicity, let's assume that psi describing our particle is a superposition of two eigenstates: |psi> = c1 |1> + c2 |2>, i.e., |c1|^2 + |c2|^2 = 1. Without loss of generality we can pick: c1 = x and c2 = sqrt(1-x^2) exp(i phi), where x is a real number smaller than 1. The density matrix of this pure state can then be written as rho = |psi><psi| and one by writing the explicit form of this density matrix one can see that the diagonal terms are: x^2 and 1-x^2, while the non-diagonal terms are: xsqrt(1-x^2) exp(i phi) and xsqrt(1-x^2) exp(-i phi).
In the most complete scenario of a measurement, the density matrix of the system can change change in many ways including the diagonal terms of the density matrix. However in this simplistic example, a measurement will by necessity, bring only the non-diagonal terms to zero (I hope most of the interested readers will have enough background to understand why).
Now, the measuring device, as a macroscopic object, will have the number of degrees of freedom far greater than the simple particle which's state we're about to measure. This number will be the order of the Avogadro number (~ 10^23) - even the smallest human visible indicator will be this big. The measurement, by necessity, includes an interaction of our small system with the enormous measuring device.
Before the interaction the whole system (the particle and the measuring device) can be written as a tensor product of the two wavefunctions:
|Omega_before> = |Psi> ⊗ |Xsi> = ( c1 |1> + c2 |2> ) ⊗ |Xsi>
where |Xsi> represents the wavefunction of the measuring device and everything it interacts with before the measurement. When the interaction occurs the state of our measuring device changes unitarily (as everything in nature) according to the full Hamiltonian of the system, and with some regrouping of the terms, we can write the state after the interaction as:
|Omega_after> = c1 |1> ⊗ |Xsi_1> + c2 |2> ⊗ |Xsi_2>
This is the true state of the system as performed by nature. The individual subsystems are no longer in pure states, but the whole system |Omega_after> (if we're able to completely describe it) - is.
Now, comes the final part, which some call the "collapse", but in reality it is just "an average" over all possible states of the bigger (measurement) system *which we declared apriori to not be the system of interest and states of which not able to follow because we measure with it*:
Tr_{over the degrees of freedom of Xsi} |Omega_after><Omega_after|
In result we obtain a matrix after the measurement which is just formed with the diagonal elements x^2 and 1-x^2, i.e., the probabilities of the two measurement results and non-diagonal terms being equal to zero.
Why are they zero? Let's inspect one of the non-diagonal elements over which the above trace is taken: x*sqrt(1-x^2)exp(i phi) <Xsi_1|Xsi_2>
It is effectively zero, because the trace over the degrees of freedom of Xsi is a mutliple integral, again of the multiplicity of order of Avogardo number and a similar number functions which change in various ways. It is enough that only a fraction of such integrals will have a value lesser than 1 to guarantee that the product will be equal to zero.
And this is all. Any attempt to change this fact would need to reject quantum mechanics completely, because probability calculus is at the heart of it.
Two particle interactions show nothing like wave function collapse, neither to three of four. Until you say a reasonable number of particles that make up the measuring apparatus where we should see _something_ weird starting to happen theoretically you're not even wrong.
You're whole thesis rests on the fact that this should fall out when we put 6e23 particles together for reasons.
So far we've not managed to simulate 1,000 quantum particles because the curse of dimensionallity means we run out of computers on earth rather quickly. Which makes anything you're saying pointless since we can't ever check it, even if we turned the whole observable universe into a computer.
What I'm trying to explain to you is that: 1) The wavefunction is only the DESCRIPTION of the underlying phenomena. 2) Within this description everything, and I mean ::everything::, evolves unitarily. No exceptions ever. 3) Whenever you decide to measure, i.e., probe the microscopic system with an object that is not within your quantum description, that is you know that it's huge, but have no details about all the phase/amplitude information you're destined to average/trace over the unknown states. This can be done symbolically (as in my first post here) and shown to always give probabilities in the reduced density matrix. That's always what we're left with in case of a large system outside of our description interacting with a small system within our description. On the other hand if you put a small quantum system, with another small quantum system (say two particles), there's no need to trace/average/apply the born rule immediately because your description can be complete both in principle and in practice. You can just unitarily evolve the system for as long as you wish/can compute for. However sooner or later you'll want to measure, because ultimately that's what physics is all about - verifying your predictions with experiment - and you go back again to small vs big, because that's the only way we, humans, can perceive this microscopic reality - through probing. The result will be completely analogous to the one before, the only change being that you'll now be able to predict probabilities of a two-particle system.
If you're familiar with electrodynamics it's quite similar there, but here it's brought to another level with the probabilistic interpretation. What are the similarities? You can have your complete description with the four-potential, about which you know, from the Aharonov-Bohm effect, carries more information than electric/magnetic fields alone although we only measure fields not the electric/magnetic potentials. The potentials were the side product of the formalism that turned out to have real consequences. Similarly as we learned the importance of the wavefunction/phases in the description, even though we only measure probabilities.
About the curse of dimensionality, the only thing I have to add is, that's true. We have a precise way to describe what is going down there but it's insanely expensive to simulate in all detail. That's still a lot to be happy with in my opinion.
Also, if you feel uneasy with wavefunctions which have the status of descriptions of reality, go and study classical field theory in which the fields are to be thought of as real physical entities, go step deeper and you're in quantum field theory in which you deal with descriptions again. Would a theory in which we deal with "real physical entities" be better than that of "descriptions"? I'd say, the hell with it. Go with whatever works best, not whatever fits your preconceived notions of reality.
there is nothing "dumbed down" in the John von Neumann book "Mathematical Foundations of Quantum Mechanics"
> Is there a good ... idiots guide to interpretation of quantum weirdness ? I am more than a little lost
I’ve got you covered. And believe it or not, you’ll be joining Tiktok University today:
https://www.tiktok.com/t/ZTRHqk6MP/
Tiktok has been quietly amassing a huge library of educational content, and I’ve been diligently sorting those into collections. I’ll post several more related to physics.
https://www.tiktok.com/t/ZTRHqLx2k/
https://www.tiktok.com/t/ZTRHqBn2L/
Why entangled electrons can’t communicate information: https://www.tiktok.com/t/ZTRHqBCLq/
Heisenberg uncertainty principle: https://www.tiktok.com/t/ZTRHq8XN3/
https://www.tiktok.com/t/ZTRHqY49j/
A more advanced one: https://www.tiktok.com/t/ZTRHq2pYS/
And a break from quantum weirdness, just ‘cause I like it: https://www.tiktok.com/t/ZTRHqBQHE
I have pages and pages of videos, so I probably shouldn’t spam them here. I can post more if there’s any interest.
Once it learns you're a science nerd it fills your feed with some high quality educational content like this. The chemistry stuff they have is also A+.
The pressure is enormous for writers to include mumbo-jumbo, because people click on these articles expecting to find out that it's possible to alter the Universe with psyhic abilities, which is how quantum physics is represented in social media, especially TikTok.
It amused me to no end when my elderly aunt came to ask me for a tl;dr; on Quantum Physics. She stopped me shortly asking how she can control the universe with her mind.
I tried to explain a bit about the famous interpretation (Copenhagen, not Von Neumann–Wigner) but she would have none of it because the business course she just attended had a segment on how to control the universe and proceeded to disregard and mock me.
"Many worlds" or "the wave function never collapses, you are in a superposition" both make much more sense with how we currently view the world
I think scientifically we will look back on “humans are uniquely conscious” as a categorical differentiation instead of a gradient with other mammals to be as absurd as believing the earth is the center of the universe. “Unique consciousness” is a quasi-religious mechanism we use at a societal level to not run around all the time terrified of death.
As for the theory of consciousness, of course we are not special, it's information-processing, and it looks like thermodynamics is responsible for the emergence of information-processing structures.
In normal human-scale billiards, there are immense numbers of photons flying around bouncing off everything. The photon interactions are far too small to affect the path of a moving billiard ball, but we can detect them easily with our eyes. So we can use photons to passively observe the balls rolling around.
But when you’re trying to observe a photon itself… there are no tiny photon-equivalents flying around. It’s like playing billiards in pitch black: the only way to know which direction a ball is rolling is to touch it. And you can’t touch a rolling billiard ball without changing its path somehow. Likewise, you can’t “observe” a single photon without interacting with it in some way.
Are you saying that the Von Neumann–Wigner interpretation[1] does not explicitly postulate consciousness to be necessary for the completion of the process of quantum measurement?
1. https://en.wikipedia.org/wiki/Von_Neumann%E2%80%93Wigner_int...
I should've said no interpretation in the 21st century.
That's a really interesting paper, thanks for that. It's also a bit depressing to consider that there's a good chance that everything we think that makes us special is really just an emergent property of a thermodynamics memory and prediction system.
It also helps us justify eating other lifeforms, mammals included.
Come to think of it, maybe that's more common in short stories, where the "gotcha!" format works. It's probably harder to spin that unchangeable-history gimmick out to novel length, whereas "you can change history and it has endless weird side effects" can work well in long form. I can't think off-hand of any time travel novels with unchangeable history.
But it's stupid as a serious time travel proposal. Things like "travel in back in time 5 seconds unless you see your future self is already there" create a hard paradox that this logic cannot solve. Time loops are easily broken by anyone interested in testing them.
Edit to add: your comment reminded me specifically of a Ted Chiang story, "What's Expected Of Us": https://www.nature.com/articles/436150a
I found that link via a blog post that excoriates it for its supposed logical fallacies: https://loopingworld.com/2019/07/13/debunking-ted-chiang-rec.... I don't necessarily agree or disagree with that, but I do disagree that it's "obviously" logically wrong or inconsistent.
Like, the free will to do something other than what you saw your future self do? Yeah, you do have that. You have that ability even as a completely deterministic brain.
Heck you could send a machine to go back in time 5 seconds that displays a number 1 greater than the number it just saw its future self display from the previous travel and your time loop has infinitely increasing state with no human in the process. Or the mundane, send a bomb back in time to destroy the time machine and your past self. It's very easy to think of examples.
> Time loops are only a problem if you insist on being able to simulate reality by computing the next time step from previous ones, without discarding any
yes?
Harry Potter has this as a plot point in one of the books. He essentially teaches/inspires himself to a spell to save the day.
I prefer Many Worlds because it is a simpler explanation, so I follow Occam's razor. That's it.
Consciousness and the existence of qualia remains a fundamental mystery. There is something definitely special about it, in the sense that it currently does not fit any scientific model. It is also a deep philosophical problem that started being considered millennia ago and dates at least all the way back to Plato vs Aristotle.
In my experience, people who think that consciousness is somehow a settled matter simply haven't thought about it enough and are perhaps a bit naive on the many ramifications of the issue that have been explored do far.
One could and many have argued that the reality we’ve been observing and operating in is consciousness. The “real” world could be entirely different and largely inaccessible.
These kinds of thought exercises don’t have much practical utility, apart from one very important feature; they humble you. At the end of the day we don’t fundamentally know anything, and should always recognize that at its most basic root level, everything we do is an educated guess. A fundamentally skeptical and curious outlook that acknowledges our perceptual limitations is how we got all of the sophisticated models of very difficult to observe phenomenon in the first place. If we want to continue to get the best understanding of whatever it is we’re experiencing, I think it’s very important to stay humble and ensure our knowledge is treated as a hard earned set of well reasoned guesses rather than unquestionable dogma. 99.9% of objections to well established ideas and models might be a waste of time entertaining, but you never know what might turn out to be the seeds of a whole new universe of understanding that invalidates huge swaths of our existing corpus of knowledge.
Most of what I’m saying here is probably obvious to a lot of readers, and I don’t think anyone in this thread is being particularly arrogant or dogmatic, but I think it’s worth reiterating. If people who understand the limits of knowledge aren’t constantly emphasizing the fact that we don’t know what we don’t know, that creates fertile ground for both dogmatic assertions and unreasonable skepticism, and I think a huge amount of dysfunction in the culture at large is explained by insufficient well calibrated humility amongst otherwise very intelligent people who set an example for others.
Zillions of new invisible universes being created every moment is the simplest explanation you found?
MWI still postulates the equivalent of wave function collapse, but instead of it happening only for the quantum system being measured, it is happening in the mind of the observer, as each "version" of that mind gets entangled with a single "version" of the outcome.
Even if you were to accept that this process is more natural (so not an "assumption") than wave-function collapse in principle, that simplicity completely falls apart when you then need to recover the relationship between the probability of observing a certain outcome and the amplitude of that outcome in the wave-function.
CI just says "when a quantum system described by a wave-function interacts with a measurement apparatus that measures in a certain basis, the wave-function gets updated to one of the values of its decomposition in that basis, with a probability equal to the modulus of the square root of its amplitude in that basis". Of course "measurement apparatus prepared in a certain basis" does a lot of work here, as we don't know how to define this in terms of a quantum system.
To make a similar quantitative prediction, MWI needs to define something like "the number of worlds", so that it can then say something like "when a quantum system interacts with a measurement apparatus prepared in a certain basis, the measurement apparatus becomes entangled with the quantum system such that for each value of that basis state there is a number of worlds proportional to the square root of the amplitude of each value of the decomposition in which the apparatus sees that particular value; if we were to compute the probability that we happen to live in a world where the apparatus is showing the value X, that probability would naturally be higher the more worlds there are where it shows this value X". So, the MWI has to actually introduce extra elements (the worlds and their number, and the observer wanting to compute a probability) to explain the actual measured results of quantum experiments.
I have never understood how that is a strong objection. We've experimentally determined that the state you are more likely to find yourself in is based on the squared amplitude. How is this different from CI but with probability of observing given state - which was also determined empirically?
> Of course "measurement apparatus prepared in a certain basis" does a lot of work here, as we don't know how to define this in terms of a quantum system.
Yes, this is where the Occam's razor bit comes in.
> So, the MWI has to actually introduce extra elements (the worlds and their number, and the observer wanting to compute a probability) to explain the actual measured results of quantum experiments.
The worlds and their number are equivalent to the states & probability of CI without having to introduce the "measurement apparatus" that is distinct from the quantum system.
It's not different, that's the point. For both interpretations, the relationship between the probability of observing a certain outcome and the amplitude of that outcome in the wave function are an extra postulate, the exact same extra postulate in fact, the Born rule.
> The worlds and their number are equivalent to the states & probability of CI without having to introduce the "measurement apparatus" that is distinct from the quantum system.
The measurement apparatus as a separate thing from the quantum system was actually partially explained by decoherence (ironically discovered by MWI proponents), which needs this separation for the same reasons as CI: we need some way to explain why quantum phenomena don't happen at our scale. Now, MWI makes this concept relative to an observer, whereas in CI it is often assumed to be absolute.
Basically, we can deduce from the Schrodinger equation alone that after the interaction of a quantum system with the environment, coherence is lost, and the different "states" of the wavefunction can no longer interfere with each other.
CI postulates that, as a result of this interaction, only one of the states will remain, with the Born rule probability. This is the most direct way of interpreting our experimental results.
MWI says that nothing changes after this interaction. It postulates though that, if we were to ask how likely we are to be in the same "state" as a particular result, we should expect that to be the Born rule probability. This explanation takes the theoretical description of the wave function to be more real in some sense than the actual observations we make.
I disagree that the decoherence at all partially explains a different measurement apparatus separate from the system. After observation, we still have the the system is in a superposition of multiple states. How this system "collapses" to one state in the measurement apparatus is unexplained.
Decoherence explains why each state of the observer can't tell that the other states also exist.
> This is the most direct way of interpreting our experimental results.
Sure, except we have to invent an entirely new non-unitary transformation of "collapse" despite all observations and predictions of quantum mechanics showing that unitary evolution of the wavefunction continues even for large macro-scale objects.
Sure, but, again, decoherence doesn't explain (1) why the wave function is split in the classical states (position, momentum etc.) and not other states (linear combinations of position and momentum and spin etc.); and (2) doesn't explain why different states have the precise probabilities of being observed that they do. You still need to postulate these features.
> Sure, except we have to invent an entirely new non-unitary transformation of "collapse" despite all observations and predictions of quantum mechanics showing that unitary evolution of the wavefunction continues even for large macro-scale objects.
You're confusing the map for the territory. What we can see, plain as day, is that unitary evolution of the wavefunction does not continue for macro-scale objects. MWI explains this through the framework of the universal wavefunction and its mutually un-interacting "branches", CI explains it through wavefunction collapse. No one has ever successfully put a macroscopic object in superposition, so the idea that the universe itself could be in superposition remains highly theoretical at best.
Note also that movement in the classical world (and in GR) is often highly non-linear/non-unitary (such as the movement of a free pendulum, or many kinds of orbits). While far from perfect for this, the Born rule at least allows us to "sneak in" non-unitary evolution through this collapse; but, in the MWI, we predict that the movement of a free pendulum should in fact be non-chaotic. This is rarely discussed, but is an interesting observation that could be experimentally tested as we get better at creating larger and larger systems that remain coherent for longer and longer periods of time.
I agree that (1) is a strong objection that I do not have an easy solution to. (2) I think is addressable in the same way that it is in CI - our theory has to explain our observed experience and the born rule (whether CI-flavored or MWI-flavored) is how we do so.
> No one has ever successfully put a macroscopic object in superposition
But getting larger and larger. https://www.nature.com/articles/s41567-019-0663-9
Thanks for an informative discussion!
Absolutely, but I would still say that it means we are adding an extra postulate that can't be derived directly from the Schrodinger equation even in MWI. I'm not trying to claim that the MWI is wrong: just that it is not simpler than the CI (nor it is more complex though - I'm arguing it has the same number of postulates).
> But getting larger and larger.
Sure, and I'm really hoping we'll advance closer to macroscopic objects in my lifetime, so maybe some of these questions may be elucidated.
> Thanks for an informative discussion!
Thank you as well!
It's not postulated, but deduced from the Schrodinger equation. MWI is simpler in a sense that it has one fewer axiom. But Occam's razor isn't really applicable here, because it selects from otherwise equal theories, which CI isn't. There are more important criteria to use before Occam's razor.
Who is “we” in this comment? Christianity and Islam emphasize consciousness and the uniqueness of human experience, and their adherents still account more than 50% of the population.
As much popularity as the many worlds theory is gaining, the generic “we” almost certainly still doesn’t believe it, and many (most?) probably don’t even know about it.
In fact, it is precisely the MWI that requires human observers for its explanations, at least to some extent, as it makes the entire notion of a classical world a fiction that only exists inside your own head because you are the one that's getting entangled with a quantum system. Any probability you compute in MWI is relative to you personally, since in MWI any possible event happens with probability 1 when checking at the universe level.
That’s why. If it’s observable it could be observed by an observer in an observation.
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.
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?
It's probably overall neither much more or less reliable than other social media like reddit, twitter, instagram and, sorry boys, HN.
The article didn't include it for lulz and clicks. It's directly relevant.
And why shouldn't he explore what changes would be needed to accommodate the new evidence? That's not the behaviour of a crank convinced his theory must be right regardless of any evidence. It's just a natural thing to think about when a theory is falsified. He's never described Orch OR as anything more than speculative.
And frankly, what else would you expect him to do? He's 91. It's astonishing that he's still doing this sort of work at all. He's hardly going to start from scratch with a completely fresh theory at this stage, although if anybody could it would be Penrose.
more seriously, having spent countless nights thinking of QM, it feels a bit like Nature is playing w you and your nerves.
I.e. if we have 3 fields, with respective coordinates [0, 1, 2], [1, 2, 3] and [2, 3, 4], a particle emerges only when the 3rd point of field A, the 2nd point of field B and the 1st point of field C, all with value = 2, are activated.
If the quantum field activations happen periodically, but their periods do not match, or the fields have different granularity when they are activated, then we may get a wave-like outcome for particles, since the interactions of all the fields happen only when the fields are synchronized at specific points in their history.
EDIT:
Writing the above made me realize that the underlying fabrique of the universe may work like a neural net, where each possible point in the universe is actually a node in a neural net, and each node has multiple fields connected to each node, and values flowing into the fields excite the nodes based on a function, for example accumulation. When a limit is exceeded in a node, a particle is created, or a particle disappears (for black holes).
A neural net of such proportions could be called ...God (yeah, I said it, sorry...I don't believe in a God but the parallelism is interesting, at least to me, from a philosophical perspective).