The paper itself is here:
https://www.science.org/doi/10.1126/science.abl7152
It's paywalled and unfortunately I have not been able to find a preprint on arxiv.org.
That comment is short, succinct and understandable, it's the best summary of the physics involved that I've heard in so few words.
It seems to me that we don't put sufficient emphasis into considering potentials. Viewing things from the aspect of potentials I reckon changes one's perspective, and I think the Aharonov-Bohm effect is a case in point, without doing so we easily come aground.
However, the Aharonov-Bohm effect still perplexes me more than I'd like - in QM, why exactly does potential have observable effects? Why is it that a phase shift occurs in the wave function of a charged particle in the near vicinity of a solenoid even though both magnetic and electric fields are negligible? (I'm either not convinced by explanations that I've heard to date or thst I don't fully understand them.)
Whilst my understanding of the Aharonov-Bohm effect is deficient in this regard, it nevertheless seems to me that if the effect can also be detected in a gravitational field context then we've likely found a profound and deeply relevant connection between EM fields/relatively and gravity. If verified, then we'd have to consider it a breakthrough in our understanding of what up until now has been an intractable problem.
The key point is that we've now experimental evidence for such a connection and that's really good news.
I'm not sure I'd say it's a breakthrough since theorists have expected it all along. And current treatments of this all have a key limitation, that they are using non-relativistic QM. Which in practice works fine since all the experiments we can currently do in this area are well within the non-relativistic domain.
A real breakthrough would be a relativistic quantum theory that included gravity as well as the other interactions. But that's probably still some way off.
Yeah, sometimes one has to be optimistic. I'm aware of the limitations of using non-relativistic QM but it seemed to me that this experimental connection, if confirmed, would encourage or even force relativistic work to center stage.
Essentially, both theoretical and experimental practitioners could now say 'we've now a concrete stating point'. On reflection, I wouldn't expect a full GR explanation to come easy. Still, it's a start.
The simple answer is that it's right there in the Hamiltonian, and the Hamiltonian is the central operator in QM, the one that determines time evolution. The fact that the EM potential appears there has been known almost as long as QM itself. Much of the recent QM experimentation in gravitational fields has been making use of recent technological advances to verify, what theorists have expected all along, that the gravitational potential acts just like the EM potential in the Hamiltonian.
It's a while since I last looked at Aharonov and Bohm's '59 paper but if I recall your point about the Hamiltonian is covered there. My understanding is that in this paper the key difference from the earlier work to which you also refer is that their new solution to the Hamiltonian now involves a phase factor.
The point I should have made was that I wasn't thinking so much about the mathematical explanation of the Aharonov-Bohm effect but in more general terms where perhaps this new experimental work may reinvigorate interest in the subject and in related areas.
Whilst QFT provides us with an exquisitely accurate mathematical account for the purposes of calculation, it says little about the underlying physics per se. Thus, it seems to me that we stil have a limited understanding about the nature of say virtual particles, ZPE, etc. and essentially no understanding of why the electric, magnetic and fine structure constants and others are the values they are.
Research into the Aharonov-Bohm effect, could eventually lead to a deeper more fundamental understanding of the subject although, given past history, I fully accept that coming up with a major breakthrough in the near future is probably unlikely. (It's even more unlikely that we'll resolve the constants problem anytime soon, if at all.)
It seems to me that the most significant aspect of this work is that we now have more than just a theoretical framework that connects EM and gravity/the gravitational field at a QM level (or seemgly so). Tenuous it may be but it seems like a good start.
For my part, I still worry about why, say, the electric and magnetic constants have the value they do or why our understanding of ZPE is seemingly at odds with reality given the ludicrous value of the calculated zero-point radiation of the vacuum. But then, this is more about philosophy than it is about physics.
Re SQUIDs, likewise, I could amuse myself for ages if I had several to play with.
Importantly, it's "famed" and "eerie."
> Notably, the particles weren’t in a gravitational field–free zone. Instead, the experiment was designed so that the researchers could filter out the effects of gravitational forces, laying bare the eerie Aharonov-Bohm influence.
I'm no physicist, but I think they calculated the expected influence and compared that with a measurement.
Regarding the "never touch", gravity decreases with distance squared, so it diminishes quickly with distance. There is a big difference in being near the mass, as opposed to feeling the dimished effect of it from far.
No, they didn't. They measured a phase shift in the particle's wave function. There is no "gravitational force" in free fall, and the particles were in free fall.
> gravity decreases with distance squared
The Newtonian gravitational force does, but the Newtonian gravitational force is irrelevant for an experiment conducted in free fall, as this one was. The gravitational potential is the key thing being measured, and it's not the potential due to the Earth, it's the potential due to a 1-kg "source mass".
> There is a big difference in being near the mass, as opposed to feeling the dimished effect of it from far.
The particles were near the 1-kg source mass.
Right, it seems that for many the 'potential' worldview is hard to grasp (it was for me too until it drawned on me that it's important).
I blame this on poor training and poor textbooks, they don't emphasize the importance of potentials. Also, we seem to grow up with a 'fields' perspective, electric fields and so on.
Maxwell was on the 'right' path with his original formulation of his equations where potentials were involved. However, when Heaviside reformulated them to the 'vector' view we quickly lost the 'potential' one.
No doubt, Heaviside's formulation is incredibly useful in electrical engineering and eleconics and as you'd know that's how they usually appear in textbooks. Trouble is, outside advanced physics texts the 'potential' view is usually omitted. Educators really need to fix this.
Another problem is that the description of a potential is not up to scratch. All too often we seem to be stuck with highschool physics descriptions - those that involve pith balls. The concept that we never measure absolute energy, but only differences often gets lost when describing potentials.
You'd reckon that after Feynman's well documented whingeing about the fact he wasn't taught about potentials early enough that you'd think by now educators would have had sufficient time to have rewritten their notes but apparently they've not.
One path of the particle in superposition was closer to the 1.25Kg mass than the other path, and they did measure a difference when doing that.
I don't know if you are trying to be pedantic, or just want to contradict. I know what you are saying, but the the expression "not touching the field" makes perfect sense to me. Try plotting the 25cm distance difference for the 1.25Kg mass, and see if it makes a difference or not...
They measured a phase shift in the wave function, as I said. They did not measure any direct difference in "gravitational effect" on the particles, as for example a difference in bending of their trajectories due to the source mass would be.
> the expression "not touching the field" makes perfect sense to me
The problem with it, as several commenters have pointed out, is that you can't shield anything from gravity. The "not touching the field" comes from electromagnetism, where you can shield things from the field. So the "not touching the field" interpretation, while it works for EM, does not work for gravity.
what is free fall in a reference frame is a particle subject to a force in another reference frame.