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Quantum particles can feel the influence of gravitational fields
- deleted 3y ago[deleted]
- cowboysauce 3y agoThe article's description of the Aharonov–Bohm effect seems kinda misleading to me. It's not that particles are being affected by a field that's not there, it's that the particles are affected by the electromagnetic potential, which can be non-zero even though the field is zero (the two are related through some simple equations).
- kurthr 3y agoSo to be simple you're saying the field is the slope (or actually gradient) of the potential. So if it's constant (but high) there is no slope, but significant potential, like being on a mesa. And that difference in potential rather than slope affects the paired quantum particles?
- AnimalMuppet 3y agoIt's not the electric field; it's the magnetic field. There is still a potential, but the potential is a vector. My ability to picture what is going on has never extended to the magnetic vector potential, so I have no intuition about how that plays in here...
- cowboysauce 3y agoThere is an electrical variant of the effect, it just hasn't been well tested experimentally.
- cowboysauce 3y agoRight, but pairs of particles aren't relevant. The effect occurs for any particle that interacts electromagnetically. And the magnetic field is the curl of its potential.
- bobbylarrybobby 3y agoKinda. The magnetic field is the curl of the vector potential. If the vector potential is nonzero but curl-less then you get zero magnetic field, but the particles’ wavefunctions still feel the vector potential. (Specifically, the phase of the wavefunction is affected; obviously nothing observable about a single wavefunction could be affected in the absence of a field, via the correspondence principle. But when you have two electrons, that phase difference does show up in their interference pattern.)
- eternauta3k 3y agoI think I understand the Aharonov–Bohm effect for magnetism, but I don't understand how you can have the branches at different gravitational potentials without the packets experiencing a field somewhere when they branch/join.
- kurthr 3y agoI'm trying to figure out how gravity has curl?
- rnhmjoj 3y agoSome argue that it's neither a non-local interaction (the test particle being affected despite no field in its region) nor that the interaction is caused by the four-potential, which would then be physical and more fundamental than the field tensor. On the contrary, it may just be an artefact of the semi-classical treatment that is normally done: classical theory for the fields, quantum one for the test particle. See this, for example: https://arxiv.org/abs/1110.6169 https://arxiv.org/abs/1110.6169
- zitterbewegung 3y agoSo if I am reading this correctly this is basically an observation that the Aharonov-Bohm effect can be done by gravity on entangled particles ? I’m guessing this won’t provide much insight on theories for quantum gravity?
- Koshkin 3y agoWell, you never know... The current explanation of this (and of the original) effect uses the classical interpretation of the field involved.
- dguest 3y agoThe title here leaves off "they never touch", which is important to show evidence for for the Aharonov-Bohm effect. Having quantum particles feel the influence of gravitational fields isn't exactly news.
- SerpentJoe 3y agoI could point out several that are doing that very thing right now.
- kazinator 3y agoIncluding particles that have no rest mass. E.g. photons: light follows the curvatures in space/time that are linked to gravity.
- mikhailfranco 3y agoObservation of a gravitational Aharonov-Bohm effect https://www.science.org/doi/10.1126/science.abl7152 https://www.science.org/doi/10.1126/science.abl7152
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- _8j50 3y agoPardon the stupid question but since most experiments and observations are done on earth, how do scientists know that fundamental forces like electromagnetism and the strong force are not being influenced by gravity? What if chemical/atomic bonds and molecular structures don't form the same way or require more/less energy depending on gravitational influence? As a layman, I would think that gravity pulls down sub-atomic particles, wouldn't that slow them down compared to say outside the heliosphere and oort cloud? Would electrons spin faster if they are located at an inter-galactic void? More insane is the measurement of 'c', is all using electromagnetism, but if that in itself is being slowed down by gravity, well I can't even begin to comprehend the implications.
- antognini 3y agoIf the electromagnetic force changed in some way depending on the gravitational influence then atoms would produce different spectral lines. However, we can observe the spectral lines produced by atoms and molecules in the interstellar medium where the net gravitational force is much weaker. There is no difference between these lines and what we observe in the lab. (Except for certain expected effects from the reduced pressure like reduced Doppler broadening and the appearance of "forbidden" lines.)
- _8j50 3y agoBut if the atoms produced different spectral lines, wouldn't observers on earth just end up wrongly believing they are seeing a different type of an element? For example you might think a star is made up of hydrogen when it is made up of helium? I have no knowledge of how spectal lines work so pardon my ignorance once more, but is it possible for gravity or other forces to produce spectral lights of similar elements than the original one or is it a very unique fingerprint not similar to close by elements? Also, if gravity can bend light (blackholes), how come it cannot attenuate it? Light is on the EM spectrum and the speed of light is different in different mediums so I am presuming it is similar to how electrons attenuate on copper wire.
- rnhmjoj 3y ago
- dschuetz 3y agoWhat the hell are "quantum particles"?
- Koshkin 3y agoI guess, this is a shorthand for "particles studied in quantum physics."
- I_Am_Nous 3y agoIn this case, they mean particles they have hit with a laser to split into superposition, so "quantum particles" = "particles in superposition".
- nh23423fefe 3y agoobjects described by wavefunctions
- magicalhippo 3y agoJust a layman but whenever I read that, I interpret it as "particles exhibiting quantum phenomena", like superposition or entanglement. This would be unlike classical particles which does not exhibit these effects.
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- grooverider 3y ago[dead]
- Jeff_Brown 3y agoI thought all gravity from everything touched everything.
- Suffocate5100 3y agoNow, how do they know? Have they interviewed any quantum particles?
- Koshkin 3y agoNo need (and who wants to be lied to, anyway?), the behavior observed was quite telling.
- russellbeattie 3y agoI mean, they have to, no? To the best of my understanding, gravity isn't a force, it's the bending of space around us caused by mass. Everything is forever moving in a perfect straight line from its perspective, but that line is curved depending on the mass of nearby objects, which affects the speed of movement (time). We're all moving around the Earth, which moves around the sun, which moves around the galaxy, which moves around the universe. This includes all particles which makes up everything. The idea that the gravitational field has no effect on them makes no sense. The question is simply "how much" of an effect.
- stevenjgarner 3y agoI struggle with this too. Is gravity a force or a geometry? (or both?)
- analog31 3y agoI have a physics degree, and struggle with it too. Granted, my degree was 30 years ago and I've been working in industry, so I haven't maintained my theory chops. The way it was explained in our graduate QM class was that certain operations in QM theory only work in Cartesian space. This is probably an over simplified statement of a Hard Problem, which is that QM and gravitation are both known to be exquisitely accurate theories, but mutually incompatible.
- NotYourLawyer 3y agoIt’s not about fields. Everybody knows fields affect particles. This is about the gravitational potential.
- Koshkin 3y agoBut without a field there is no potential, is there?
- ergonaught 3y agoShould put 2022 in the title.
- bilsbie 3y agoI wonder if you could use these as a gravity detector. Like detect if you’re in a gravity field?
- simne 3y agoAs I understand these matters, you could know, if quantum entangled particle enter gravity field. Must admit, I don't know how this experiment will be organized, but looking possible.