[HN Gopher] Quantum particles can feel the influence of gravitat...
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Quantum particles can feel the influence of gravitational fields
Author : galaxyLogic
Score : 71 points
Date : 2023-12-01 05:48 UTC (17 hours ago)
(HTM) web link (www.sciencenews.org)
(TXT) w3m dump (www.sciencenews.org)
| cowboysauce wrote:
| The 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 wrote:
| So 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 wrote:
| It'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 wrote:
| There is an electrical variant of the effect, it just
| hasn't been well tested experimentally.
| cowboysauce wrote:
| Right, 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.
| rnhmjoj wrote:
| Some 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
| zitterbewegung wrote:
| So 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 wrote:
| Well, you never know... The current explanation of this (and of
| the original) effect uses the classical interpretation of the
| field involved.
| dguest wrote:
| The 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 wrote:
| I could point out several that are doing that very thing right
| now.
| kazinator wrote:
| Including particles that have no rest mass. E.g. photons: light
| follows the curvatures in space/time that are linked to
| gravity.
| mikhailfranco wrote:
| _Observation of a gravitational Aharonov-Bohm effect_
| https://www.science.org/doi/10.1126/science.abl7152
| badrabbit wrote:
| Pardon 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 wrote:
| If 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.)
| pdonis wrote:
| First, we have extensive observational data from elsewhere in
| the universe that tells us that the fundamental interactions
| work the same everywhere. For example, we see light coming from
| regions that have very different gravity, but it still behaves
| the same.
|
| Second, on the scale of atoms, or even on the scale of ordinary
| macroscopic objects, gravity is so extremely weak that its
| effects on things like chemical bonds or the structure of
| nuclei, atoms, and molecules is negligible. If you have a very
| massive object like a star (or a white dwarf or neutron star),
| then of course you have different states of matter possible
| (degenerate matter in stellar cores, white dwarfs, and neutron
| stars), but even those states of matter still have all the
| fundamental interactions working the same way. The different
| states of matter are due to the extreme density and pressure,
| not due to any change in the fundamental interactions.
|
| Third, what we usually call "the speed of light in vacuum" is
| actually a property of spacetime, not specifically of light. So
| the idea of this speed being "slowed down by gravity" is based
| on a confusion. That property of spacetime (a better name for
| it would be local Lorentz invariance) is the same everywhere no
| matter how weak or strong gravity is.
| rkagerer wrote:
| Isn't gravity a property of spacetime? (curvature)
| petschge wrote:
| You can describe it that way. But different parts of
| spacetime can have different curvature, so you get
| different impact of gravity. No matter how you describe it,
| gravity is different on Earth, Moon or in deep space and
| your theory has to model that no matter if it uses forces,
| curvature of spacetime or something else.
| dschuetz wrote:
| What the hell are "quantum particles"?
| Koshkin wrote:
| I guess, this is a shorthand for "particles studied in quantum
| physics."
| I_Am_Nous wrote:
| In this case, they mean particles they have hit with a laser to
| split into superposition, so "quantum particles" = "particles
| in superposition".
| nh23423fefe wrote:
| objects described by wavefunctions
| magicalhippo wrote:
| Just 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.
| Jeff_Brown wrote:
| I thought all gravity from everything touched everything.
| Suffocate5100 wrote:
| Now, how do they know? Have they interviewed any quantum
| particles?
| Koshkin wrote:
| No need (and who wants to be lied to, anyway?), the behavior
| observed was quite telling.
| russellbeattie wrote:
| I 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.
| NotYourLawyer wrote:
| It's not about fields. Everybody knows fields affect particles.
| This is about the gravitational potential.
| Koshkin wrote:
| But without a field there is no potential, is there?
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