I’m probably way off base and I’m probably missing some insights that I could get by going to school or something but that’s was just my experience with the subject.
--Richard Feynman
You're far from alone. Quantum physics is tricky because it frequently doesn't agree with our physical intuition. Humans are used to dealing with macroscopic objects. They surround us for our whole lives. Matter behaves in surprisingly different ways at the level of single quanta. Seemingly impossible things flop out of the math and then clever experiments show that reality is consistent with the math, but we struggle to reach the point where that reality feels correct. When we try to translate the math into human language, we often wind up overloading words and concepts in a way that can be misleading or even false.
Perhaps we just haven't reached the point where things are sufficiently well explained and simplified, but it may be be that quantum physics will always seem strange and counter-intuitive.
Quantum physics tricky for two separate reasons.
(i) The mathematical theory (Schrödinger equation, wave function, operators, probabilities) is solid and well-defined, but may feel unintuitive, as you say.
(ii) But quantum mechanics is also an incomplete theory. Even if you learn to be at peace with the unintuitive aspects of the mathematical theory, the measurement problem remains an unsolved problem.
"The Schrödinger equation describes quantum systems but does not describe their measurement."
"Quantum theory offers no dynamical description of the "collapse" of the wave function"
https://en.wikipedia.org/wiki/Wave_function_collapse#The_mea...
> macroscopic objects
It's not about scale at all though. It's just that small systems tend to be observed with this other, specific property that we associate with causing "quantum" like effects. Not only do those effects happen at mesoscopic scale but aside from gravity, quantum theory already can be and is used to describe things on large scales too. Classical computers and desks are still "quantum" systems. Recently theory and experiments have developed to connect with gravity in many ways. I'm more confused when people say something is mysterious. They're usually referring to apparent randomness but I think even that is explained already with partitions or even just wave math (complementarity).
I always fell back on "Spooky action at a distance"; If Einstein found it weird, I shouldn't feel that bad if I can't quite make sense of it.
A school would usually teach the "shut up (about philosophy) and calculate" approach. These philosophical problems about the meaning of quantum mechanics have been with us for 100 years, and mainstream physics sees them as too hard or even intractable, and thus as waste of time.
Either quantum computers work (at least in principle), or our understanding of the universe is way off and we are getting exciting new physics.
The mathematics of QM works extremely well.
The interpretations of what the math is saying happens a varied and sometimes contradictory.
We can predict what's going to happen extremely well, we just can't tell the story of what's happening. And there's been a century of trying to avoid the weirdness and failing. The problem might just be our brains evolved in a world that behaves so much differently that we can't understand.
Yes but also absolutely not. The evolution of the wavefunction when nobody is looking is unitary, which among other things means it is time-reversible. That math works extremely well and predicts the correct outcome.
When we are measuring a quantum system, the probability distribution of the measurement outcome is described by the Born rule, the amplitude of the wavefunction squared, and the collapse postulate tells us that after the measurement the wave function will be in the measured state, which is a non-unitary and non-time-reversible process. That math works extremely well and predicts the correct outcome.
But - really big but - what is a measurement device but a huge quantum system, what is a measurement but a quantum system and a measurement device and an environment undergoing time evolution? So both descriptions should apply, unitary time evolution and wave function collapse, but that can not be the case because they are incompatible, one is unitary, the other is not. The mathematical description is inconsistent.
A great example involves flipping a coin. Even people who know it's basically an independent 50/50 chance every time get drawn into thinking about "hot streaks" and "overdue for the opposite."
It's arguably a superpower that has given us lots of agriculture and tools and technology and culture, but like hunger and obesity we can't just turn it off when it gets maladaptive.
Could you form a specific question that you're wondering about? (Have you looked at condensed matter physics yet?)
https://arxiv.org/pdf/1811.09062
However, it still doesn't really address the core question of when the collapse actually occurs. All it really seems to add is that the environment is an "observer" and that decoherence actually causes the collapse.
The math is fairly well known, and people can successfully apply it. As evidence in eg modern CPUs and GPUs and RAM actually working. And lots of other marvels of modern engineering that requiring an understanding of quantum mechanics to design and engineer.
Nevertheless, commercial quantum computers exist and do exactly what scientists predicted they would do.
The wave function is still symmetric, but it takes on a bimodal distribution, with very little overlap. For any given event, it will be affected only by the half of the distribution that it's in. The other half has basically zero effect. The further time evolves, that effect becomes even smaller -- as in, the odds of an experiment demonstrating it quickly go towards 1 in 10^googol^googol.
You can round that down to exactly zero and call it "collapse". Or you can keep thinking about the entirety of the wave function, and call it a "multiverse". That rounding is technically invalid, but it simplifies the conceptualization (and the math) to a massive, massive degree without affecting the outcome in any pragmatically measurable way.
(One more caveat: "symmetry" implies we're talking about a wave function with a 50-50 superposition. That's not a requirement, but it simplifies an already complex explanation.)
Does this not imply that there is an asymmetry, one half of the state gets imprinted, the other half neglected? This however also raises the question about the basis, what is a superposition and what is not depends on the choice of basis. Is there a special basis just as pointer states are somehow special?
https://www.quantamagazine.org/quantum-darwinism-an-idea-to-...
I feel that it really just gives an explanation of decoherence, but doesnt offer any testable hypothesis for darwinian pruning and collapse to pointer states.
The author does say the approach is a combination of Copenhagen and MWI, removing the outlandish parts of both. Seems to preserve the randomness of the former though.
Well, duh. It's not like classic objects actually exist, or the classical/quantum divide: everything is quantum, including the "observers". The "classical observer" is a crude approximation that breaks down to a pointy enough question. Just like shorting the perfect battery (with zero internal resistance) with a perfect wire (with zero external resistance) — this scenario is not an approximation of any possible real scenario so it's paradoxicality (infinite current!) is irrelevant.
To call something random doesn't mean it's impossible to model, in fact all sorts of natural facts seemed random one day before being covered by a model. One very relatable example example is the motion of stars in the the night sky, which seemed random for ages, until the Copernican revolution.
The fact we have access to random() function in programming seems to trip many people. random() is a particular model implementation of random, but stuff in nature isn't random().
My point is, using "just random" to do work in any scientific explanation is a clutch.
Hardly. Some philosophers say that. But I don't take much from philosophers reasoning about physics.
#2: What's so bad about thinking about life as an exciting rollercoaster ride? The tracks are laid but the ride is still fun.
[0] https://robkoons.net/uploads/1/3/5/2/135276253/prime_matter_...
[1] https://robkoons.net/uploads/1/3/5/2/135276253/hyl_esc_acpq_...
[2] https://robkoons.net/uploads/1/3/5/2/135276253/koons_the_man...
[3] https://robkoons.net/uploads/1/3/5/2/135276253/ejps_quantum_...
The quantum function is the real object. Little balls we like to imagine the particles as are just perception of quantum functions very narrowed down by entangling with macroscopic objects. The way we measure anything is through the entanglement between the measured entity and our macroscopic instruments.
seconded
>might make sense to link to the actual material you're referring to
https://www.youtube.com/watch?v=sshJyD0aWXg
In a fews sentences: the evolution of a physical system (quantum and classical) can very successfully be modeled as a stochastic process, and ...
1. state of the system is a real-valued "vector" (could be a vector of with continuous indices), or to put it another way, a "point" in state space.
2. system evolution is described by a real-valued "matrix" (matrix in quotes because it is also possibly a matrix with continuous indices), defined by the laws physics as they apply to the system
3. evolution of the system is modeled by repeatedly applying the matrix to the system (to the vector), possibly with infinitesimal steps.
The major discovery Jacob made is that, historically, folks working on stochastic processes had restricted themselves to studying "markovian" stochastic processes, where the transformation matrix has specific mathematical properties, and this fails to be able to properly model QM.
Jacob removes the constraint that the matrix should obey markovian constraints and lands us in an area of maths that's woefully unexplored: non markovian stochastic processes.
The net result though: you can model quantum mechanics with simple real-valued probabilities and do away entirely with the effing complex numbers.
The whole thing is way more intuitive than the traditional complex number based approach.
Jacob also apparently formally demonstrates that his approach is equivalent to the traditional approach.
Really worth taking a read/listen at.
This article is making some pilot-wave-like claim on top of quantum Darwinism that while the Schrödinger equation is real, all the 'real realness' exists in some pointer to a specific location inside it. Why does it do this? Where does this claim come from? At least collapse theories allow that the thing the Schrödinger equation is modelling is actually real up until the part God gets out his frustum culler.
Photons (and other objects that seem to behave 'quantumly') do not seem subject to this (and thus we can use them to understand quantum behavior) because they have particular properties wherein their behavior is not as affected by these macroscopic drop-offs quite as badly.
https://www.cambridge.org/core/books/decoherence-and-quantum...
https://en.wikipedia.org/wiki/Betteridge%27s_law_of_headline...
Actually, the "many worlds" "interpretation", simply treats the highly successful equations as meaning what they say.
And it is misnamed. The field equations describe a highly interconnected "web universe" of "tangles" (what I call spans of entangled interactions) and "spangles". (My shorthand for superpositions, i.e. disjoint interactions of particles. Think of all the alternate lines leading from and two distinguishable states, like star patterns.) Basically, a graph of union and intersection relations where all combinations, individually and en masse, are determined exactly by the laws of conservation.
That's an amazingly good property for a theory. And we have it.
By including all consistent versions, no external information is required by the theory. It is informationally complete. A successful objective explanation. With deep experimental support that entanglement and superposition actually exist, because their interactions are easily testable.
In fact, entanglement doesn't "violate" locality, it is the more general case which explains locality. Locality is just tightly coupled entanglement/interaction. Not a fundamental constraint on connections. There is no fundamental "distance", just loose and dense connections. Locality is just what we see wherever there are patterns of dense connections. They are an effect, not a constraint.
Even in the classical world of large (highly tangled) objects, we take it for granted that dependent objects can separate over arbitrarily vast dimensions of space and time and yet return together. If that isn't entanglement over vast distances, what is it? It is a basic property of classical physics. Quantum mechanics reveals more subtlety in those maintained connections, including interactions between connections, but it didn't originate them.
Forces disappear. They become passive in an interesting way. Histories where information cancel, leave structured distribution patterns behind, which to us look like forces. Cancellation is just information being conserved. Not an active force. But the results appear active.
In a similar way to how the evolutionary umbrella seems very smart and creative, when really, it is just poorly adapted individual creatures independently cancelling themselves out blindly, leaving a distributional improvement behind.
There is no additional information needed to explain the effect of quantum "collapse" because it is already explained by the fast bifurcation of disjoint tangles when lots of particles interact in an unorganized manner. It is thermodynamics being thermodynamics.
Anyone attempting to invent a mechanism for "collapse" is like someone trying to explain why the spherical Earth appears "flat" by introducing additional speculative theories. Despite the spherical world theory already explaining why it looks flat locally.
And the only reason to not take the experimentally verified field equations as a plain reading, is the result is "too big" for someone's imagination.
Our everyday experience doesn't limit reality, despite humans having trouble with theories that reveal a bigger reality, over and over and over.
Bluntly: The total field equations preserve information - that is the plain implication and guarantee for having both unions (tangles) and intersections (spangles) of interactions.
Anything else requires a universal firehose of magically appearing information to choose collapses, i.e. particular interactions, in order to explain something already explained. In other words, dressed up voodoo. And by "re-complicating", uh, "re-explaining" the already explained, introduces a ridiculous new puzzle: Where does all that pervasively intrusive relentless injection of information (that determines every single extricable particle interaction!), come from? (Occam is spinning like a particle accelerator in his grave.)
Saying it "Just Happens" is like someone "explaining" their pet version of a creator with "Just Is". It is a psychological non-taulogy for "Don't Ask Questions".
The Stanford Encyclopedia of Philosophy (https://plato.stanford.edu/entries/qm-manyworlds/) goes into this in some depth, and it seems like the right way to think about it is say that "I" in one branch is a different entity than the "I" in a different branch. I have somehow not been able to grok it yet.
And I agree about the naming. I really dislike the name "many worlds interpretation", which seems to imply that we have to postulate the existence of these additional worlds, whereas in fact they are branches of the wavefunction exactly predicted by standard quantum mechanics.
Pour water down a hill. Water clings to water, and we have hills that already have lots of correlations. We get streams that break up into multiple streams.
How did one stream end up where it is? It seems like a good question, but it is circular. The stream is defined by where it is. You are here (in some circumstance), because the version of you in this circumstance is you.
A transporter accident that creates several versions of you, on several planets with difference colors, doesn't need to explain to each version how they ended up at a planet with their color. Even if for a particular copy, it seems like there should be an answer why they showed up on a planet of a particular specific color. The "why" is just, all paths were taken.
That's quite a serious issues. And arguments against that - like Self-Locating Uncertainty, or Zurek's Envariance - look suspiciously circular if you pull them apart.
There's also the issue that if you don't have a mechanism that constrains probability, you can't say anything about the common mechanism of any of the worlds you're in. Your world may be some kind of lottery-winning statistical freak world which happens to have very unusual properties, and generalising from them is absolutely misleading.
There's no way of testing that, so you end up with something unfalsifiable.
Just a pleb here, but that does not stop me from thinking about it..
I think your consciousness is a function of the world you belong. So asking why your are in a certain world, and not in other, is like asking why you are born to your specific parents, and not to others.
So you don't end up in some fork, by a roll of dice, you are already confined to, and defined by a single branch.
So I don't think the exact "you" don't exist in another branch. But another consciousness that only differ from "you" by only a single random event (ie you and this consciousness only differ from you in the observation of a single random event) exist in another branch.
And it is not like this is all orchestrated by some entity. It is just how consciousness and subjective experiences emerges in mathematical structures (+ the set of random events), that does not need rendering anywhere (Mathematical Universe Hypothesis).
Once you understand the hopeless inevitablity of existence, a lot of questions like "When", "how", or "why" of our existence disappears.
You can ask if there is any proof for this, except for some thought experiment. But I think the only thing that can come close to proving this is if we exhaustively searched for other extra terrestrial consciousness and don't find any.
All experiments agree with the many worlds interpretation (again, better described as a quantum web interpretation), and it is the plain Occam's Razor interpretation.
No additional flourishes are needed. That is strong theoretical support. It is the default (plain reading) interpretation already.
And it is the interpretation that doesn't just conserve in one history (i.e. conservation of energy etc.), but conserves information universally.
So again, very strong specific theoretical support.
It is the conjectures about experimentally unmotivated elaborations, like "collapses", that would also break universal conservation of information, for no theoretically necessary reason, that need dramatic new evidence to prove themselves.
If I lack any optimism, it is for conjectured complications with no evidentiary support and weaker explanatory/conservation powers. In any other context, nobody would be entertaining the need for such conjectures.
The "Quantum Collapsers" are right up their with the "Flat Earthers", or solar system "Epicycle Theorists", for not being happy with accepting a working and successful theory as is. Even though their imagined shivs introduce more questions than they answer, and would dispense with its unique advantages.
A quantum computer is such a macroscopic state.
Is it falsifiable?
If you have a theory that seems unassailable by any logic, that's a good signal it is tautological and not very useful.
So two entangled versions of you follow, one entangled with each state. (Actually as many quantum versions of you that touched the qubit times two.)
Which is what happens, as we know from experiment when any one qubit interacts with another independent qubit. We get the product of entangled states, each now correlated. But different entangles states are now in superpostion with each other.
So correlation/entanglement happens and is experienced, despite no collapse of superposition. No information was destroyed or created.
Each of you thinks, wow now the qubit only has one state. But that is because there are two versions of you, correlated respectively with the two uncollapsed qubit states.
Complete conservation. That is the "experience" of collapse that needs no explanation, because it is a predicted experience not requiring an actual collapse. Just as spherical Earth models don't need a special explanation for the appearance of locally flat Earth, because spherical models predict a local flat Earth experience.
Zurek’s Decoherence and Quantum Darwinism is thought-provoking, but it’s still speculation without broad buy-in from researchers. We might need ASI to crack these mysteries — our brains weren’t built for this kind of problem.
Maybe ASI can help design these. Until it can, it will just be another voice arguing for one position over another on pretty weak arguments. Right now my money would be more on human researchers finding those experiments, but even among those few are even trying
Induction had the earth at the center of the solar system and had the best calculations to predict where Mars was. Copernicus said earth was at the center, the equations were simpler, but were worse at predicting the location of planets.(until we figured out they moved in ellipses)
When we say "All swans are white, because I've never seen a black swan." Its probabilistically true. That is induction. If we found swans didn't have the gene to make black feathers, that would be deduction.
Deduction is probably the most true, if it is true. (But it is often 100% wrong)
Induction is always semi true.
Quantum mechanics seems to be in the stage of induction. Particles are like the earth at the center of the solar system. We need a Copernican revolution.
Nothing is a particle, all measured things are a probability that we make a certainty when we measure them.
When you stop looking at things as things, but instead, see them as probabilities, it will all make sense. My hand and the beer bottle I pick up are both probabilities. Since the mind cannot navigate the world based on probabilities it turns them into certainties.
Physical science is is the only way we can perceive quantum science. There is no "collapse" outside of our brains perception.
