[HN Gopher] New magnetic component discovered in the Faraday effect
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New magnetic component discovered in the Faraday effect
Author : rbanffy
Score : 195 points
Date : 2025-11-19 20:53 UTC (5 days ago)
(HTM) web link (phys.org)
(TXT) w3m dump (phys.org)
| namanyayg wrote:
| We intuitively think in particles and see a world of billiard
| balls colliding with one another.
|
| But actually everything is merely waves and fields.
|
| There's going to be a time where humans finally reconcile the
| quantum with the newtonian -- and I can't wait for that day
| thaumasiotes wrote:
| > But actually everything is merely waves and fields.
|
| The two-slit experiment says otherwise.
| FloorEgg wrote:
| The way I've always thought of this is there are potentials
| for interactions and interactions.
|
| Interactions act like point particles and potentials for
| interactions act like waves.
|
| Arguing over the distinction is a bit like debating whether
| people are the things they do, or the thing that does things.
| There is some philosophical discussion to be had, but for the
| most part it doesn't really matter.
| gucci-on-fleek wrote:
| Hmm? The double slit experiment definitely shows that
| particles are waves--weird quantum waves, but still waves.
| fragmede wrote:
| what happens when you only send a single photon down the
| line though?
| mpyne wrote:
| It's worth reading about, but it's kind of wave-like even
| then: https://en.wikipedia.org/wiki/Double-
| slit_experiment#Interfe...
|
| It would be going too far to say it's only a wave though.
| It's both wave and particle.
| binary132 wrote:
| The way I read GGP was as contradicting the assertion
| that everything is just waves and not at all particles.
| rolph wrote:
| do it once, it looks like one particle.
|
| repeat the single photon launch many times, and you see a
| wavelike distribution of photon strikes
| bobbylarrybobby wrote:
| It still interferes with itself, and that interference
| affects the pattern of detections. It's as if the photon
| were a wave right up until the moment of detection, at
| which points it's forced to "particalize" and pick a spot
| to be located at -- but it's the amplitude of the wave it
| was just before detection that determines where on the
| detection screen the photon is likely to show up. If you
| send many photons through one at a time, the detections
| (each just a point on the screen) will fill out the
| expected double slit pattern.
| ggm wrote:
| I've always wondered what degree of confidence exists
| amongst the cogniscenti that a single photon event
| happened. I tend to think the criteria of measurement
| here would suggest the most likely outcome was a shitload
| more than 1 photon, and that all the "but we measured we
| can see one only" measurements are themselvs hedged by a
| bunch of belief.
|
| That said, I do like the single photon experiment, when
| it's more than a thought experiment.
| uberduper wrote:
| Double slit experiment has been done with electrons which
| are, afaik, much easier to detect and send single file.
| It's been done with molecules. It's not a thought
| experiment.
|
| Quantum superposition is real. There's no doubt about
| that.
| ggm wrote:
| Not a physicist, just here to observe single photons
| weren't reliably emitted until the modern era. like the
| 1970s. The double slit experiment pre-dates this. it's
| from 1801. The one which confirms "self interaction" was
| 1974.
|
| From the pop-sci reading I do, "detecting" reliable
| generation of single photon STREAMS in the early days
| depended on using mechanisms which inherently would
| release a sequence of photons, over time, and then gating
| the time sufficiently accurately to have high confidence
| you know the time base, and can discriminate an
| "individual" from the herd.
|
| I don't doubt quantum theory. I only observe it's mostly
| for young students (like almost all received wisdom)
| grounded in experiments which don't actually do what
| people think they do.
|
| What people do in places like the BIPM in Paris, or CERN,
| isn't the same as that experiment you did with a ticker-
| tape and a weighted trolleycar down a ramp. "it's been
| confirmed" is the unfortunate reality of received wisdom,
| and inherently depends on trust in science. I do trust
| science.
| danparsonson wrote:
| It's a wave of probability, that interferes through the
| slits and then collapses into a probability of one
| somewhere along the wavefront at the point of detection.
| Whatever that means :-)
| gucci-on-fleek wrote:
| As the other comments have already mentioned, it
| interferes with itself, so you still observe the same
| interference patterns [0] [1]. Which admittedly seems
| impossible at first, but so does the rest of quantum
| physics.
|
| [0]: https://www.feynmanlectures.caltech.edu/III_01.html#
| Ch1-S5
|
| [1]: https://en.wikipedia.org/wiki/Wave%E2%80%93particle_
| duality#...
| prmph wrote:
| > Which admittedly seems impossible at first, but so does
| the rest of quantum physics.
|
| AKA, miracles _can_ happen, hehe.
|
| I'm not trolling, this is a philosophical point I'm
| making.
| WJW wrote:
| Depends on the definition of miracle I guess. There's all
| sort of unintuitive shit going on in the quantum world,
| but we can make it happen so reliably that it's hardly a
| miracle anymore. Wikipedia defines a miracle as "an event
| that is inexplicable by natural or scientific laws and
| accordingly gets attributed to some supernatural or
| praeternatural cause". But we understand "how" quantum
| mechanics quite well, even if the behavior described by
| the equations is not very intuitive to humans.
| thaumasiotes wrote:
| The two-slit experiment shows that photons behave like
| waves if you aren't looking at them, _and_ that they fail
| to behave like waves if you are.
| layer8 wrote:
| Everett reconciled that. They only appear to fail to
| behave like waves because the observer is waves as well.
| jasonwatkinspdx wrote:
| It does not. It shows that individual photons self interfere,
| so they cannot be idealized particles.
| dcl wrote:
| Are you getting confused with the photoelectric effect
| experiment?
| farrelle25 wrote:
| Another interpretation of the double-slit posits a guiding
| 'Pilot Wave' separate from physical particles... aka
| DeBroglie-Bohm Theory or Bohmian Mechanics.
|
| Apparently it's not popular among professional physicsts
| though John Bell investigated it a bit. Einstein had some
| unpublished notes in the 1920s about a "Gespensterfeld"
| (ghost field) that guided particles.
|
| Born was influenced by this 'Ghost field' idea when he
| published his famous interpretation of the 'Wave Function'
| |Ps|^2 as a probability rather than a physical field.
|
| More info: Nonlocal and local ghost fields in quantum
| correlations. https://arxiv.org/abs/quant-ph/9502017
| mock-possum wrote:
| Pilot wave is still my favorite - I don't really believe
| it, but I like the image
| naasking wrote:
| It is indeed a great way to translate classical
| intuitions to the quantum domain.
| rhdunn wrote:
| Veritasium did a video on this [1] with a surface of oil to
| replicate the effect on a petri dish.
|
| [1] https://www.youtube.com/watch?v=WIyTZDHuarQ
| jagged-chisel wrote:
| That we're just collections of wave interference is wild.
| isolli wrote:
| We're built on so many layers of emergence, it's wild!
|
| quantum particles => atoms => chemistry => biochemistry =>
| cellular life => multi-cellular life => intelligence
| piva00 wrote:
| It can keep going!
|
| Intelligence -> societies -> technology -> ?
|
| One has to wonder how far can emergence stretch given
| enough time, some kind of entropic limit probably exists
| but I'm just a layman, hopefully someone more knowledgeable
| can share if we already know a physical hard limit for
| emergence.
| jacquesm wrote:
| I like your progression. It makes me wonder if
| intelligence could lead to technology absent societies.
| boyanlevchev wrote:
| If we take a simple definition of technology - such as
| "tool" or some external inanimate thing we use as an
| extension of ourselves - then I think all animals on
| Earth that we have deemed intelligent to some degree use
| "technology". Crows using sticks to pick things out
| holes, chimps crafting spears for hunting, dolphins
| wearing "hats", octopuses building stone fortresses, etc.
| So I guess it's important to define the limit of the
| definition of technology.
| vixen99 wrote:
| After a brilliant start (atoms etc.,) it starts to be
| problematic once one hits societies. After all, the
| earlier progressions are undeniably astounding stable
| successes in their various incarnations. A pessimist
| might say 'Stable' societies so far have tended
| eventually towards being self-destructive tyrannies.
| canjobear wrote:
| There's no problem reconciling the quantum with the Newtonian.
| Quantum mechanics recovers Newtonian mechanics in the
| appropriate limit. The problem is reconciling the quantum and
| the Einsteinian.
| sosodev wrote:
| But there's no quantum explanation of gravity, right?
| arthurcolle wrote:
| Classified
| lmpdev wrote:
| At this point we have several
|
| They're all largely untestable though
|
| String theory, LQG, half a dozen others
| fnordpiglet wrote:
| There's no explanation of gravity, quantum or no. There are
| merely descriptions.
| isolli wrote:
| Isn't everything descriptions, in the end, aka models?
| Turtles all the way down...
| B1FF_PSUVM wrote:
| "Two masses attract each other with a force F = m1 m2
| G/r^2"
|
| "OK, but why don't they _repel_ each other? "
|
| "That would make life really hard, and we wouldn't be
| here discussing it ..."
| tsimionescu wrote:
| Actually, Newtonian gravity can be added to QM and work
| perfectly well. It's GR gravity that doesn't work with QM,
| especially if you try to model very high curvature like
| you'd get near a black hole.
| rhdunn wrote:
| Quantum Electro-Dynamics (QED) is the application of
| Special Relativity (non-accelerating frames of reference,
| i.e. moving at a constant speed) to Electromagnetism.
| Thus, the issue is with applying accelerating frames of
| reference (the General in GR) to QM.
| moefh wrote:
| > Special Relativity (non-accelerating frames of
| reference, i.e. moving at a constant speed)
|
| Sorry, but this is a pet peeve of mine: special
| relativity works perfectly well in accelerating frames of
| reference, as long as the spacetime remains flat (a
| Minkowski space[1]), for example when any curvature
| caused by gravity is small enough that you can ignore it.
|
| [1] https://en.wikipedia.org/wiki/Minkowski_space
| tsimionescu wrote:
| None of these have anything to do with what I said. SR
| works just as well as classical mechanics with
| acceleration. If SR didn't work with acceleration, it
| would have never been accepted as a valid theory at all,
| it would have been a laughing stock, as acceleration was
| well understood since the times of Newton.
|
| What general relativity does different from special
| relativity is that it extends the concept of relativity
| from inertial frames of reference to _all_ frames of
| reference, even accelerating ones. In the process, it
| also explains the reason why inertial mass and
| gravitational mass happen to be the same, by tying the
| gravitational interaction fundamentally to the concept of
| acceleration.
| ithkuil wrote:
| In particular with general relativity.
|
| Quantum field theory (QFT) is quantum mechanics + special
| relativity
| hliyan wrote:
| I think neither analogy is correct. We're using macro metaphors
| (real world things at human time and spatial scales) to explain
| microscopic phenomena that may not correspond to anything that
| we find familiar.
| setopt wrote:
| I agree with this. As a physicist, I believe the most
| accurate resolution is to say that <<quantum fields>> and
| <<quantum particles>> describe neither waves (in the sense of
| e.g. water or acoustic waves) nor particles (in the sense of
| marbles and billiard balls), but a third thing that simply
| has some things in common with both classical waves and
| classical particles. The analogies are useful for
| understanding that third thing, but if you believe the
| analogies too literally, then you'll make mistakes.
| IAmBroom wrote:
| Thank you! That's a paradigm that I had in the back of my
| head, but not explicitly phrased.
|
| Photons aren't like particles nor waves. Particles and
| waves are like photons. And, as with all similes, they fail
| when you inspect too closely.
| chadcmulligan wrote:
| I don't have the math, but doesn't quantum field theory say
| this?
| gethly wrote:
| Maybe think of it as binary(particles) vs analog(waves).
| baq wrote:
| Just listen to Feynmann trying to explain why he can't explain
| magnetism in macro terms (e.g.
| https://www.youtube.com/watch?v=MO0r930Sn_8)
| K0balt wrote:
| So, are you telling me that we actually-don't- know how
| magnets work lol?
| baq wrote:
| Not at all - but we don't know how to explain how they work
| using any analogy from the macro world that we intuitively
| understand.
| zyxzevn wrote:
| 3Blue1Brown has a very good explanation of how light works as a
| wave And the barber pole effect shows how matter (sugar)
| rotates light https://www.youtube.com/watch?v=QCX62YJCmGk
|
| There is also evidence that "photons" are just thresholds in
| the material that is used to detect light. The atoms vibrate
| with the EM-wave and at a certain threshold they switch to a
| higher vibration state that can release an electron. If the
| starting state is random, the release of an electron will often
| coincide with the light that is transmitted from just one atom.
|
| This threshold means that one "photon" can cause zero or
| multiple detections. This was tested by Eric Reiter in many
| experiments and he saw that this variation indeed happens.
| Especially when the experiment is tuned to reveal this. By
| using high frequency light for example. It happens also in
| experiments done by others, but they disregarded the zero or
| multiple detections as noise. I think the double detection
| effect was discovered when he worked in the laboratory with
| ultraviolet light.
|
| Here is a paper about Eric Reiter's work: https://progress-in-
| physics.com/2014/PP-37-06.PDF And here is his book.
| https://drive.google.com/file/d/1BlY5IeTNdu1X6pRA5dnJvRq3ip6...
| ta988 wrote:
| There are so many artifacts that could cause those
| observations that I emit serious doubts that's what is
| happening in those experiments.
| uberduper wrote:
| What a timely article and comment. I've been watching a lecture
| series over the last few days about quantum mechanics and the
| many worlds interpretation. And I have questions.
|
| I may have missed it or didn't understand it when I heard it
| explained. What underpins the notion that when a particle
| transitions from a superposed to defined state, the other basis
| states continue to exist? If they have to continue to exist,
| then okay many worlds, but why do we think (or know?) they must
| continue to exist?
| moi2388 wrote:
| Because quantum mechanics describes the universe with a wave
| function, which evolves according to the schroedinger
| equation.
|
| In it, there is no notion of collapse. The only thing that
| makes sense is saying the observer becomes entangled with the
| measurement.
|
| So if you only look at the Schrodinger equation, this is the
| only conclusion.
|
| Wave function collapse is something which is simply added ad-
| hoc to describe our observation, not something which is
| actually defined in QM
| sevensor wrote:
| I disagree. Our notion of waves is no less an analogy to
| macroscopic phenomena than billiard balls. There's no avoiding
| the dual nature, and there's no problem with saying that the
| wave analogy works in some places, but the particle analogy
| works in others. The only real truth here is "neither." A
| photon is a photon, and there is no macroscopic analogy it
| reduces to perfectly.
| magphys wrote:
| > To quantify this influence, the team applied their model to
| Terbium Gallium Garnet (TGG), a crystal widely used to measure
| the Faraday effect. They found that the magnetic field of light
| accounts for about 17% of the observed rotation at visible
| wavelengths and up to 70% in the infrared range.
|
| Nearly 20% seems already significant, but 70%?! that's massive.
| nrhrjrjrjtntbt wrote:
| Nice to see a graph of % magnetic priportion and log wavelength
| going from radio to gamma.
| CamperBob2 wrote:
| How did no one notice that before, and what else have they (we)
| missed?
| gsf_emergency_6 wrote:
| If I'd to guess: all that exp. characterization to-date has
| revealed no anomaly (See my other comment)
|
| This team might have looked at bandstructure. or not (they
| didn't say, & I'd guess not)
| gsf_emergency_6 wrote:
| Seems to be a minor typo . Paper:
|
| > _17.5% of the measured value for Terbium-Gallium-Garnet (TGG)
| at 800 nm, and up to 75% at 1.3 um._
|
| Here's what the crystal looks like
|
| https://www.photonchinaa.com/tgg-terbium-gallium-garnet/
|
| Here's transmission plot (UV-IR)
|
| https://www.samaterials.com/terbium-gallium-garnet-crystal.h...
|
| Note there's almost no effect on transmission
|
| Relevant? https://dspace.mit.edu/handle/1721.1/51819
| sehansen wrote:
| Yes, the paper and magphys talks about rotation, not
| transmission.
| plaguna wrote:
| But do they understand how magnets work?
| moi2388 wrote:
| The fact that the explanation of how a magnet works is that it
| is made up of smaller magnets infuriates me.
| hinkley wrote:
| MRIs work because water molecules are tiny magnets.
| ghostpepper wrote:
| Obviously hindsight is 20/20 but this sentiment just reeks with
| comical levels of hubris
|
| > However, the new research demonstrates that the magnetic field
| of light, long thought irrelevant,
| agentifysh wrote:
| so what exciting applications can we see from this?
| geocar wrote:
| We will put a box containing a little light and a magnet into
| every home and people will lose their goddamned minds looking
| at it every day
| moi2388 wrote:
| Hmm.. if only we could force this to somehow display ads..
| discoutdynamite wrote:
| This isnt exactly new. This is a obvious and predicted effect of
| ECE Theor. I'm surprised that neither the article nor any other
| commentor mentioned it yet.
|
| tl;dr on ECE Theory: Gravity is a curvature of spacetime,
| electromagnetism is a torsion.
| prmph wrote:
| From Wikipedia:
|
| Einstein-Cartan-Evans theory or ECE theory was an attempted
| unified theory of physics proposed by the Welsh chemist and
| physicist Myron Wyn Evans ..., which claimed to unify general
| relativity, quantum mechanics and electromagnetism. The
| hypothesis was largely published ... between 2003 and 2005.
| Several of Evans's central claims were later shown to be
| mathematically incorrect and, in 2008, the new editor of
| Foundations of Physics, Nobel laureate Gerard't Hooft,
| published an editorial note effectively retracting the
| journal's support for the hypothesis.
| Noaidi wrote:
| I'm sorry if I offended anyone's consciousness by bringing this
| up, but this can affect how we view the health effects of radio
| frequency electromagnetic fields.
|
| Since the magnetic fields of these EMF's can pass deeper into the
| body than the electric field, that would mean that the magnetic
| field can affect many of the voltage gated ion channels in the
| body. That's including the brain.
| wasabi991011 wrote:
| > Since the magnetic fields of these EMF's can pass deeper into
| the body than the electric field,
|
| Can they actually though?
|
| I'm not an expert, but to my knowledge the penetration depth of
| an electromagnetic wave depends only on its frequency. I can't
| find anywhere online that makes a distinction between electric
| waves and magnetic waves.
| Noaidi wrote:
| When the electromagnetic wave hits a substance, it splits
| into separate electric and magnetic waves. The electric wave
| does not penetrate deeply, but magnetic waves can go through
| anything. Magnetic waves can only be diverted, not blocked.
| kawfey wrote:
| Maxwell's equations have yet to be disproven but this
| comment implies otherwise.
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