We are getting into definitions and common usage debates, which is the most uninteresting debate to have. I will simply state that “quantum mechanics” unqualified typically refers to the description of reality developed on Copenhagen in the 1920’s. When people are referring to quantum field theory, they are usually explicit in doing so.

Not true at all. Blackbody radiation goes to infinity with Wien's distribution; error bars aren't going to get you there.

Likewise, our 1/r^2 understanding of forces goes to infinity as distance goes to zero, but we currently can't resolve that problem with error bars for the nucleus of an atom, where Heisenberg tells us any two protons can sometimes appear closer to each other than the "radius" of the nucleus.

You can't make Schottky diodes using Maxwell and error bars.

That is the entire problem: the classical models weren't merely inaccurate; they predicted completely absurd (and provably wrong) results at extreme scales.

What? What are the more precise theories that aren't fundamentally QM?

>The problem with Wolfram/Gorrard's model is that it doesn't relate to any experiments

That's because quantum gravity regime is so far experimentally inaccessible?

Quibble: "Gorard".

Fair point. Thanks for the link!

I don't believe all possible extensions have been ruled out: e.g. right-handed neutrinos are still a viable dark matter candidate as far as I know, and these are in fact motivated by the standard model, because every other fermion has both right and left chiral forms.

https://en.wikipedia.org/wiki/Sterile_neutrino

So likely dark matter is a different flavor of something already in the model. Dr. Mills' Hydrino theory presents hydrogen with the electron in a lower orbit that does not radiate as a candidate for dark matter. These states are stable like the ground state. Transition into or between hydrino states emit light in the UV or soft X-ray wavelengths that is not seen in optical telescopes.

https://brilliantlightpower.com/atomic-theory/

Intuitively speaking, if dark matter interacts only with gravitational field, then it's not affected by most standard model symmetries. A field bubble, so to say. Tachyons are somehow thought of as possible, meaning standard model doesn't say much about them?

How can insights into large scale structure formation help explaining galaxy ration curves, lensing observations or barionic acoustic oscillations?

There are degrees of offtopicness, of course. In this case I moved the subthread because it was a generic tangent that had little to do with the specific article.

Good on-topic subthreads usually show some sign of contact with the body of the article—not just the title, and certainly not the most generic phrase (in this case "quantum mechanics") that can be abstracted from the title.

But one can always argue particular cases either way and I agree that the counter-argument was stronger for that one.

> The bent shape and specific bond angle are the direct, deterministic result of the nuclei

That then contradicts the fact that ions form orbitals according to their number of electrons, not according to their nuclear properties. That was also known before quantum mechanics.

A flexible spherical shell of charge orbiting an atom necessarily has an axis of rotation and an angular momentum and would thus be oblate. Furthermore, if we neglect quantum effects or prefer to think of them as not real, such a shell would have a continuous set of possible angular momenta, which is not observed. In fact, the ground state, say, of the hydrogen atom, has zero angular momentum and thus, from that point of view, is simply not equivalent to any sort of orbit whatsoever, or perhaps we prefer to think of it as a superposition of orbits which has the property that the angular momentum is zero - but the BLP ontology does not admit superpositions.

Furthermore, the properties of these sheets of electron material seem quite outlandish. Consider the ground state spherical state. If we force it to have zero angular momentum to match observation, then the shell must be rigid, but as you know, a rigid shell does not actually have a stable orbit around a central charge (this is kindergarten physics, feel free to work it out).

Things get worse when we consider high energy states which do have angular momenta. Does the nucleus get stick in one lobe or the other of the charged sheet, which is now infinitely thin (and thus dense) at the center?

This doesn't even begin to get into the myriad other reasons we use quantum mechanics and reluctantly give up our classical ontology besides just the description of atomic orbitals. To meet all these other demands (eg, Bell experiments) with the "sheet of charge" ontology is at least a herculean task which BLP's material does not accomplish (I have read it) and at worst has even greater foundational challenges than quantum mechanics. After all, we know "wave function collapse" (which I use here to refer simply to the totally uncontroversial measured phenomenon without an interpretation given) indeed happens "instantaneously" over spacetime - for a totally classical ontology this phenomenon is beyond peculiar and would indeed involve genuine signals propagating faster than light. At least in quantum mechanics we can understand wave function collapse in alternative ways which do not involve the violation of the laws of special relativity.

And this doesn't even get into how one would formulate QFT in the BLP picture. QFT isn't without its challenges, of course, but its a basic generalization of the structures of quantum mechanics. I don't know of any place where BLP calculates scattering amplitudes correctly, but feel free to show me where he works out ABC scalar field theory or whatever.

In the end the appeal of any theory needs to be evaluated in the full context of human knowledge, not just against a narrow set of objections about some qualities of a given theory. BLP seems motivated by a basic distaste for some of the weirdness of QM but evaluated in total, against the total sum of experiments routinely carried out in the world and against basic physical intuitions from even classical physics, it doesn't hold up.

This isn't true. For example, at the bending magnets in a particle accelerator there is a constant current of electrons moving through the bend but those electrons still radiate. From far away the charge density at the turn is constant, but the current density is not constant. You cannot eliminate current density by squinting - classically accelerating charge radiates.

If we have a classical scale beam of electrons released into a constant magnetic field it radiates as it moves in a circle, even if the instantaneous charge density at any point on the circle is constant. In fact, speaking purely classically, the current density is instantaneously constant at a given point on the circle but it still radiates because in order to maintain itself on a circular path the charge must accelerate, even if the speed stays the same.

Of course as the action of the system approaches hbar (as it must as the energy radiates away) the system begins to have quantized energy levels, as quantum mechanics correctly predicts.

Aren't you literally describing the conditions that create synchrotron radiation?

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Engineering is how science gets out of the lab...

How else does science get 'out of the lab'?

Most of the science going into the Manhattan Project was experimental measurements and phenomenological models, not fundamental physics at the QM level. There were no usable quantum-mechanical models of nuclear physics at that point.

No; they didn't really need it.

Nucleon orbitals rely a little on Pauli exclusion principle, which you need to add as an ad hoc hypothesis every time in classical physics.

>did we really need quantum mechanics to build an atom bomb?

Yes. Nuclear reactions require understanding and modeling of the strong force, you can't understand or even see what protons and neutrons are without understanding the strong force. The mixture of positively charged and neutral particles being stuck together with enormous force which essentially does not exist at all outside of the nucleus of an atom. (there is more than three pounds of force between every pair of protons inside every nucleus with the strong force counteracting the electrostatic force)

You couldn't design a bomb without being able to model the strong force and you couldn't get to that point of investigating the atom without coming up with QM.

You couldn't get the idea of isotopes and enriching U-235 to U-238 or transmuting uranium to plutonium without understanding QM.

Or the circumstances that would lead someone to blindly creating a controlled nuclear reaction without coming up with QM in the process would be pretty absurd.

The idea for the bomb came from the understanding of the strong force. Step one: notice that there's a crazy powerful force keeping positively charged particles stuck together in the nucleus. Step two: the eureka moment of realizing you can "release" that force by causing a chain reaction of fission in heavy elements.

The very idea of matter and energy being quantized into particles and photons is the starting point of “quantum” mechanics.

I don't know dog, that is a pretty bold statement given everything we can presently firmly say about the universe.

Like we can imagine some kind of purely deterministic thing going on but when the rubber meets the road the best ways of working stuff out seem to very strongly imply some fundamental indeterminism. No one likes it, but thats the way it is.

Nature doesn't obey your opinions.

Of course it is. What you are suggesting is classical determinism.