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It’s time to admit quantum theory has reached a dead end

nautil.us

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Re: It’s time to admit quantum theory has reached a dead end

#61

Post by TheOtherHobbes »

renox wrote: post #24
tus666 wrote: post #3

Yes, but go back to philosophy not math. All the evidence suggests the "particle" interpretation of QM is simply wrong, that light or energy really is just a self propagating wave, which explains the double slit experiment cleanly, and is not incompatible with energy levels or quantization if formulated correctly. Experiments that claim to show light consists of particles need to be reassessed wearing a philosopher's…

Yes, I never understood why light was considered 'particles' :-( As far as I understand it is because light can only be emitted by atoms with discrete energy levels, but (IMHO again) light is emitted by atoms with discrete energy levels because it is emitted when electrons jumps from one energy level to another and that the possible trajectory of electrons around the atoms aren't continuous, I don't see how this is r…

Light is considered a particle - or more accurately has particle-like behaviours in certain contexts - because you can count individual photons. The energy varies with frequency, and it arrives in discrete lumps at discrete locations. You can't have half a photon. It's all of a photon or no photon.

It's one of Einstein's key insights, one of the foundations of quantum theory.

In Quantum Field Theory you have quantum fields. There are no 'waves' and no 'particles', there's only a 3D probability density field which defines the probability of particle-like events at specific locations. It's the probability field that is 'wave-like', and particles are considered excitations of the field.

So you know you're quite likely to see an electron-like or photon-like event in one location, and not at all likely in another.

Calling this a 'particle' is just an analogy. All you can really say is that a particle-like measurement is likely and/or did happen in one region.

What this really means - whether it's an observer artefact, or an exchange of information, or the output of some kind of computational and/or causal substrate, or something else entirely - is still a mystery.

Re: It’s time to admit quantum theory has reached a dead end

#62

Post by PartiallyTyped »

beaconstudios wrote: post #25
geijoenr wrote: post #5

For some time already we are in an "epicyclean phase" of physics, trapped by the extraordinary predictive success of Quantum Electrodynamics and still using mathematical methods devised in the 19th century (variational calculus). This has lead us to the current situation, with extremely complicated theories at the limit of human understanding that bear no new results. It will take a modern day Copernicus to come up w…

Are more modern information-theoretic and dynamical models not used for quantum mechanics? They're both relatively recent and extremely innovative mathematical models. Granted, I'm not mathematically fluent enough to know if they represent a deviation from variational calculus!

There is constructor theory

https://www.youtube.com/watch?v=hYc97J2MZIo

Re: It’s time to admit quantum theory has reached a dead end

#63

Post by alar44 »

dekhn wrote: post #49
alar44 wrote: post #41

Earlier quoted context omitted.

We absolutely understand protein folding. The fact there isn't a closed form simple solution to tell us the shape of a protein shouldn't be surprising at all. It's just hard to calculate. It's like the 3 body problem, but there are 90. I don't know why you think there would be some simple solution to that that doesn't involve simulation and heavy computation. You'd need 8 dimensional 100x100 matrices or something to…

We do not understand protein folding. I'm an expert in this field with publications and what you just said makes no sense at all. The simplified protein folding problem states that proteins fold to their energy minimum, and a succesful heuristic can find the "correct" fold by finding the structure argmin(energy). Although this is a real simplification that doesn't represent actual proteins, even that is not something…

I used matrix math as a hand wavey example of how one might purely numerically describe the angles in a structure. What don't we understand? We know the forces of all the atoms that act on each other, what is the mystery at this point other than calculating it is hard?

Re: It’s time to admit quantum theory has reached a dead end

#64

Post by fennecs »

Amusing to see all the pessimistic comments form programmers who have zero understanding beyond high school maths thinking somehow there is a magic solution to all the problems in physics like you can just refactor everything.

Quantum field theory is definitely not stuck in the 1920s. Modern physics has a lot more going on than 19th century mathematics. We understand quite a lot about the mathematical structure underpinning quantum field theories.

Quantisation is a nearly well understood process, it’s not simply heuristics and guesswork.

Unfortunately, it’s not like much smarter than anyone posting here haven’t considered lots of wild ideas, it’s just that a lot of them haven’t worked, and we have been funnelled into what we currently have. There are infinitely many more interesting mathematical objects and ideas possible than what is allowed.

Quantum mechanics, or say quantum field theory, has really good predictive power. What ever comes next needs to at least be consistent. Unfortunately I think things are going to get more complicated. Don’t use your intuition developed from grinding out web crap to try and reason about the forefront of human knowledge.

Re: It’s time to admit quantum theory has reached a dead end

#65

Post by JumpCrisscross »

lacker wrote: post #47
geijoenr wrote: post #5

For some time already we are in an "epicyclean phase" of physics, trapped by the extraordinary predictive success of Quantum Electrodynamics and still using mathematical methods devised in the 19th century (variational calculus). This has lead us to the current situation, with extremely complicated theories at the limit of human understanding that bear no new results. It will take a modern day Copernicus to come up w…

It will take a modern day Copernicus We might already have a modern day Copernicus. Could be string theory, could be something else. The problem is that we don't really have any experimental data that can't be explained by the Standard Model. What we really need is a modern day Galileo that can perform some sort of observations, like finding Jupiter's moons, that don't fit in with the existing conventional physics.

> we don't really have any experimental data that can't be explained by the Standard Model

What was the evidence Copernicus saw that epicycles didn't explain? (Honest question.)

Re: It’s time to admit quantum theory has reached a dead end

#66

Post by pshc »

esteth wrote: post #53
pshc wrote: post #35

Earlier quoted context omitted.

The energy comes from the incredible magnetic force spent to align the atoms when the magnet was created, and it will be slowly exhausted over time.

Why would it be exhausted over time? When things come close to the magnet it uses its potential energy to pull them. When some force acts to remove those objects from the magnetic field, that energy is converted into potential in the magnet again. Are you claiming that the alignment of the magnet will fade slowly over time when the field is interacted with, more quickly than it would if it were left on a proverbial s…

Yeah, that was my claim, that the atoms will slowly return to a chaotic high-entropy organization over time, and more rapidly as forces are exerted against the magnet. I guess I was wrong.

Re: It’s time to admit quantum theory has reached a dead end

#67

Post by LeapingLennie »

petmon wrote: post #51
renox wrote: post #24

Earlier quoted context omitted.

Yes, I never understood why light was considered 'particles' :-( As far as I understand it is because light can only be emitted by atoms with discrete energy levels, but (IMHO again) light is emitted by atoms with discrete energy levels because it is emitted when electrons jumps from one energy level to another and that the possible trajectory of electrons around the atoms aren't continuous, I don't see how this is r…

We have several single photon sources, including nitrogen vacancy centers and quantum dots. Nobody has ever produced a "half-photon source" though.

What would half-photons look like? I guess photons with half the energy expected given their wavelength and the Planck relation E = hc/λ?

Re: It’s time to admit quantum theory has reached a dead end

#68

Post by dekhn »

alar44 wrote: post #63
dekhn wrote: post #49

Earlier quoted context omitted.

We do not understand protein folding. I'm an expert in this field with publications and what you just said makes no sense at all. The simplified protein folding problem states that proteins fold to their energy minimum, and a succesful heuristic can find the "correct" fold by finding the structure argmin(energy). Although this is a real simplification that doesn't represent actual proteins, even that is not something…

I used matrix math as a hand wavey example of how one might purely numerically describe the angles in a structure. What don't we understand? We know the forces of all the atoms that act on each other, what is the mystery at this point other than calculating it is hard?

"We know the forces of all the atoms that act on each other, what is the mystery at this point other than calculating it is hard?"

might be true, but it's computationally intractable and even if you did find a way around it you'd just learn that your force field was inaccurate, or that proteins don't actually fold to their energy minimum.

Not just hard, but NP-hard. In fact, the "protein folding problem is NP hard" is misleading; in fact, the "static protein structure problem" is NP hard, and protein folding is "harder" than that (it's a superproblem of static structure prediction).

The way to describe angles for a protein is this: you use degrees or radians to describe the torsion angles of the backbone (2 torsions per amino acid, 360 possible positions per torsion, times the number of backbone atoms in the protein). Treat side chains with rotamers, that's already a solved problem. However, you can't compute self-collisions in angle space you need to embed the protein structure in cartesian coordinates, which is how they are normally represented (as a graph representing the bond topology, and an N*3 array of positions).

Re: It’s time to admit quantum theory has reached a dead end

#69

Post by mellosouls »

fennecs wrote: post #64

Amusing to see all the pessimistic comments form programmers who have zero understanding beyond high school maths thinking somehow there is a magic solution to all the problems in physics like you can just refactor everything. Quantum field theory is definitely not stuck in the 1920s. Modern physics has a lot more going on than 19th century mathematics. We understand quite a lot about the mathematical structure under…

Don’t use your intuition developed from grinding out web crap to try and reason about the forefront of human knowledge.

Have you tried front end web frameworks recently? String theory has nothing on them.

Re: It’s time to admit quantum theory has reached a dead end

#70

Post by ISL »

I disagree strongly with the author's pull-quote that "We know nothing more than Bohr, Einstein, Schrödinger, and Heisenberg."

There has been roughly a century worth of experiments since the quantum theory came into being. Those experiments have scythed through myriad attempts to explain the mechanism by which quantum theory apparently describes reality.

Physicists can choose between interpretations of quantum mechanics according to "taste" precisely because there are no observable ways to differentiate between them. As soon as those ways become available to us, "taste" will give way to experimental tests.

There is still ample room for cleverness. Experimentalists are pushing forward where we can, but another observation like Bell's might be sufficient to allow, pardon the pun, a quantum leap.

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