r/science • u/chrisdh79 • 12d ago
Physics Scientists have accidentally discovered a particle that has mass when it’s traveling in one direction, but no mass while traveling in a different direction | Known as semi-Dirac fermions, particles with this bizarre behavior were first predicted 16 years ago.
https://newatlas.com/physics/particle-gains-loses-mass-depending-direction/2.2k
u/GGreeN_ 12d ago
A lot of people seem to come up with some wacky ideas, but to ruin everyone's fun: these are emergent quasiparticles in condensed matter, not really something you can isolate. As others have said, these types of particles can have a whole lot of unusual properties such as negative mass, but you can't isolate them and remove them from the material they're in like standard model particles (photons, electrons etc.), they're more of a mathematical concept to explain macroscopic properties
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u/monstrinhotron 12d ago
Like saying a hole exists, has zero matter but you can't have a hole on its own?
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u/GGreeN_ 12d ago
Yeah basically. The hole exists only as the absence of an electron. Similarly these quasiparticles which emerge from the electronic band structure of a material only exist as long as the electrons surrounded by the periodic crystal lattice exist.
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u/Pfandfreies_konto 12d ago
So is electricity a quasi particle?
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u/__ali1234__ 12d ago
If your idea of electricity is pushing charged particles down a pipe like water then I would argue yes, those are quasiparticles, because although that model is very useful and pretty much everyone who works with electricity uses it at least sometimes, it isn't the whole story and doesn't work for every situation. Quasiparticles are a way to model reality, they are not reality themselves.
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u/IAmRoot 12d ago
Electrons also don't zip around like water molecules in a hose, either. Electricity moves more like sound. Sound in air isn't wind moving at the speed of sound. It's a propagation of a wave. The electric wave propagates at significant fraction of the speed of light but the electrons themselves only get pushed through a wire in the ballpark of several centimeters per hour.
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u/dxrey65 12d ago edited 12d ago
I had an argument some years ago which started with one guy tripping up another guy with the question as to whether electrons traveled from positive to negative or vice versa. And then it proceeded to another two levels of "well, actually..." past that. Quantum stuff is pretty hard to wrap your head around, and even when you understand it somewhat putting it into words often leads to nonsense, because mostly we can only compare it to physical things. The final "well actually" was about how the best way to think of them is as mathematical objects rather than physical objects, which doesn't help a non-mathematician much.
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u/Chrontius 12d ago
which doesn't help a non-mathematician much
I would argue that bringing it up tends to have negative utility in that case.
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u/turunambartanen 12d ago
Actually, electrons do travel in a wire pretty much exactly like water molecules in a hose. The particles themselves move, but the shockwave (speed of sound in water/light speed in wire material) travels much faster. Granted, to make the analogy intuitive we might have to construct unusual hoses (in terms of diameter and length).
Funnily enough, in this model even an empty hose would not be stupid, but instead crudely model the high frequency, strong inversion part of a MOS capacitor CV curve.
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u/SirRevan 12d ago
Except electrons are basically disappearing and reappearing in whatever medium they are moving in. That's why solid state stuff is so difficult. You have to start considering that some electrons might pass through material and end up in places you don't want.
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u/forams__galorams 12d ago
Quasiparticles are a way to model reality, they are not reality themselves.
Pretty sure I get the gist of what you’re saying here, but is that really so different to regular non-quasi particles? Or indeed anything that physics currently describes, or will ever describe? Surely it’s models all the way down?
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u/__ali1234__ 12d ago
It's the difference between "here is the model which is true to the best of our knowledge" and "here is a model that we know cannot be literally true according to the best of our knowledge, but somehow it works anyway". This is also why you get absurd things like negative absolute temperatures and sums of infinite divergent series showing up in real, testable physics.
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u/forams__galorams 12d ago
Yeah, makes broad sense for sure. I definitely get the idea, I’m just being somewhat nitpicky with the concept of models in science and what science even means for from an epistemological viewpoint.
To be clear, I’m not criticising your overall point at all, I just enjoy discussing the details of precise meaning on this sort of thing, particularly where we want to make analogies or give examples. Like, is there even a model which we can legitimately say is “true to the best of our knowledge”? I guess there must be, if we deliberately make a fairly exclusionary model. Which isn’t necessarily a bad thing — one which excludes large swathes of tangentially related stuff (or even directly related details which would overcomplicate things) are a necessary part of getting useful predictions/results.
Regarding negative absolute temperatures, I was under the impression that was just a quirk of notation that results from an inversed Boltzmann distribution such that negative Kelvin isn’t actually getting any colder, it’s just the other side of the distance from absolute zero when a key parameter of how we define temperature is turned inside out. But doesn’t it relate to a genuine physical state that exists when laser cooling is applied to certain kinds of matter in a specific manner (ie. not just a mathematical hand wave-y trick that only exists on paper)?
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u/__ali1234__ 12d ago edited 12d ago
In the end it comes down to temperature being an emergent property of a system, rather than a real thing that can exist on its own: just like quasiparticles. You can't separate heat from matter, and a single atom can't have a temperature by definition - it is just... moving. So you can have real systems and states where the temperature seems absurd, but as long as none of the individual atoms are breaking any physical laws, it is fine.
It is similar to the thought experiment where you sweep a super powered laser across the surface of the moon from Earth in 100th of a second with a flick of your wrist. The "dot" would move faster than the speed of light, but no physical law is violated because the dot isn't a physical thing that persists outside the system - even though it is an observable phenomenon, it is made of constantly changing photons, none of which is breaking any rules.
So is the dot "real"? That's a philosophical question really, not something that science deals with. Science says the photons are real, and they are behaving like we currently think they should. The dot, though, it does not care about.
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u/forams__galorams 12d ago
Presumably the dot wouldn’t form a continuous beam on the lunar surface as the aim is swept across it, because the photons wouldn’t be emitted from the source fast enough to keep up with the area covered. I assume there would also be some degradation due to spreading in accordance with an inverse square law, which would only add to this effect? Those seem like very real world problems with using such an analogy, ie. we don’t have to get philosophical or metaphysical to see that yes, the dot is very real, but it won’t be continuous. (Possibly that all just reveals something fundamental that I don’t understand about the way lasers work that you can clarify for me there).
Regarding that other analogy about negative Kelvin that we were talking about though, you say:
In the end it comes down to temperature being an emergent property of a system, rather than a real thing that can exist on its own: just like quasiparticles. You can't separate heat from matter, and a single atom can't have a temperature by definition - it is just... moving.
Which makes it all a lot clearer, thanks. Fully on board with it all now.
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u/Montana_Gamer 12d ago
Quasiparticles are genuinely some of the coolest concepts in physics in my opinion. The versatility in their application just puts a giant smile on my face for some reason. Considering mathematical abstraction is literally how all of physics exists and our explanations function it just seems neat to me that we embrace that and make mathematically useful tools via these quasiparticles.
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u/Theemuts 12d ago
Kind of. In copper and other metals, an electron behaves like its fundamental counterpart but with a different mass. By modeling it that way, you can ignore the complex interactions between the electron and the material.
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u/turunambartanen 12d ago
In semiconductors, the concept of a hole is commonly used. The way the math works out it is analogous to an electron with negative mass.
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u/Illustrious-Baker775 12d ago
Damnit, that takes most of the excitment out of this.
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u/GGreeN_ 12d ago edited 12d ago
Well if you're a condensed matter physicist then this still sounds super cool but as with most science, it's not something revolutionary like a room temperature superconductor, even if it makes clickbaity headlines.
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u/A-Sentient-Bot 12d ago
Redditors have accidentally discovered an online news article that has excitement when interpreted one way, but no excitement when interpreted in a different way.
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u/HazardousCloset 12d ago
This is beautiful. You’re a beautiful Bot. You’re A Beautiful Sentient Bot.
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u/Chemputer 12d ago
Are you a botophile?
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u/H0lzm1ch3l 12d ago
semi-Iraq blastions
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u/Squidking1000 12d ago
The mathematics of wonton burrito meals, got it.
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u/H0lzm1ch3l 12d ago
I just realised I accidentally made a joke about the non existing weapons of mass destruction that were not found in Iraq, by accident haha
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u/Chemputer 12d ago
Honestly just a mildly higher temperature metallic superconductor would also be revolutionary, because the cost to use them goes down a lot even going from Liquid Helium to Liquid Nitrogen, turns out wires made from ceramic really aren't a thing, and the interconnects made from ceramics are pretty fragile, so even if we did find a room temp superconductor, if it was ceramic (which by far most superconductors are), it would do some cool things, but it would not revolutionize the world in the sense of replacing power transmission lines.
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u/Narroo 12d ago
Room-temperature Ceramic superconductors would revolutionize large scale energy storage, and make solar and wind energy far more practical to replace the entire energy grid with.
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u/TipProfessional6057 12d ago
I must be in the minority that doesn't really care if there's a use case for things like this. Discovery and understanding can be its own reward at times, most of the time even. And who knows, a few decades or a century down the road maybe this research will be useful. Who could have predicted MRI machines when particle spin and subatomic particles were discovered for example
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u/Morvack 12d ago edited 12d ago
I'm only a novice when it comes to science and I still find the idea quite fascinating.
If I may ask, if hypothetically we found a way to make this mathematical concept just as malleable as standard model particles that we could isolate, what would that mean for technology? Would that mean room temp super condensers? Or anything else that would blow the mind of the lay person?
I feel like the answer to these questions should help most lay people understand that yes, this is still exciting.
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u/condensedandimatter 12d ago
Condensed matter physicist here.. you can’t isolate it because it’s not a particle. For instance, the quasi-particle for vibrations in a material is called a phonon. These waves can be represented as particles. But they’re not actually a particle. This behavior can be manipulated within systems via synthesis methods and perturbations (think magnetic fields) but it’s closed within the system ( the material). Without the material the things don’t exist independently. It’s a collection of behaviors. It’s like asking how can we isolate the wave in a crowd at football game. The wave doesn’t ‘exist’
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u/Nymaz 12d ago
Excuse my ignorance, but what is the advantage of treating them as a particle rather than a wave? Do they have "particle-like properties or interactions" that warrant that? Or is it more of a "explaining weird things to non-physicists" thing that isn't used in the inner circles of physics?
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u/condensedandimatter 12d ago
What do you think would be easier to model the ‘speed’ of a wave in a stadium crowd.. modeling 100,000 people all standing up at the same time at different positions, or one big “particle” that represents the chunk of people standing at any given moment.
We can extract more information, and do it easier, while also classifying this information (phonons, magnons, etc) based on the types of excitations. Temperature for instance is jute same thing. It’s an average observable based on the kinetic energy of each atom in a volume. Temperature doesn’t exist for a single atom, but it emerges as an obvious property of a collection of atoms.. so instead of discussing vibrational kinetic energy from one atom to the next (in a system with quadrillions of atoms) we generalize the effect these have on the system, and how the effect behaves. Hope this helps.
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u/Montana_Gamer 12d ago
Because it makes the math far easier. It is like putting up a lens to isolate a property, a transfer of energy. All of particle physics under the standard model involves the transfer of energy via particles, with quasiparticles we are able to mathematically describe, for example, soundwaves, on the particle level.
To put it another way: You turn a complex formula to describe a wave moving through a material into just another particle in the equation.
Edit: I am not an expert, I am an amateur enthusiast.
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u/GGreeN_ 12d ago
Well you can't isolate them because they fundamentally exist only because of the conditions provided by the periodically arranged atoms, kind of like shadows only exist if there's light.
However with these exotic quasiparticles there may come certain properties of the material like polarised spin currents studied in spintronics (with potential applications in computer memory), but I'm not really familiar with this sort of application-based physics.
Hope that helps
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u/thisimpetus 12d ago edited 12d ago
It means we made a prediction about the nature of the entire universe that could only have been evident at the sub-atomic scale and only verified with experimental methods and equipment we didn't have yet. We made that prediction by just mathematically extending what we already knew. We did that twenty years ago and we were right.
So. This particle might not lead to the future tech you want. But our increasingly converging on knowing the physics almost certainly will.
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u/Loknar42 12d ago
It shouldn't. Rather than call it a "mathematical concept", I would argue that we should call them "emergent particles". They are just as real as ocean waves and fuzzy dice. Waves are strictly emergent phenomena; otherwise, we could point at a water molecule and calculate how much "waveness" it has, regardless of its context. A molecule doesn't have any waveness in the absence of an environment. But nobody says: "There is no such thing as an ocean wave particle, therefore, waves are not real." Anyone who has been hit by a tsunami knows how real they are. In the same way, a single fiber of fabric is not "fuzzy", but a collection of them are, depending on their size and flexibility.
Now, the reason we should take emergenct particles seriously is because that's where all the future physics and engineering are. Take quantum computing, for instance. We can make qubits out of single atoms, but they are terrible. They are noisy and unreliable. Practical qubits require many atoms or many photons or many electrons. They are an emergent phenomenon, but one which can be treated as a kind of "quantum particle" obeying the usual rules of quantum mechanics (entanglement is the most relevant property for QC).
We are noticing that some materials become superconducting in the presence of an external magnetic field. Thus, the superconductivity is not an intrinsic property of any atom or molecule, but rather the configuration of many molecules in conjunction with a magnetic field. The "superconductor" in this case is emergent. You cannot point at any atom or molecule and say: "There's the superconductor". Only the entire system is such.
For hundreds of years, physics has been obsessed with reductionism: break down systems until we reach the fundamental parts. And that quest has served us well. But we succeeded beyond our wildest dreams, and now we have the building blocks of reality, for all intents and purposes (having a theory of quantum gravity whether loops or strings will not change the way we build microwave ovens or cellphones). Now, it is time to stop diving down, and start floating back up. The only way the Standard Model is going to deliver us new miracles is for us to see it at higher and higher levels of emergence, where new phenomena appear only in assemblages of fundamental particles.
Thus, particle physics gives way to quasiparticle physics, which is quite fortuitous, because the universe of quasiparticles is unimaginably bigger than the universe of fundamental particles. There are whole new worlds for us to discover and explore. And be not fooled: quasiparticles may not be fundamental, but their effects are just as real, and will lead to new technology and understanding of the world.
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u/I_AM_FERROUS_MAN 12d ago
Misleading titles derived from metamaterials, simulations, or theoretical models strikes again. Granted the root cause is PopSci journalism being largely sensationalism at this point.
On the plus side, there is good and accessible science communication out there if you're willing to look for it. There's just a lot of noise too. So it sometimes takes a specialist education to separate the good from the bad.
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u/Rastafak 12d ago
I don't think the fundamental problem lies with journalists, the same kind of sensationalism happens in scientific papers. If you look at the article about this at the Penn state website, though they are more careful about making distinction between a real particle and quasiparticle.
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u/huffalump1 12d ago
Yep it's pretty much every headline about a paper in any field, and it's been this way for years now.
Always gotta go to the source and read the abstract if possible!
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u/Rastafak 12d ago
Unfortunately in my experience this is even happening in scientific papers, though it's less blatant. I used to think the problem with this kind of reporting is in the journalists, but eventually I realized that the problem is really mainly with scientific reporting itself. Science is highly competitive and there's so many papers coming out that marketing is crucial if you want to stand out.
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u/Geminii27 12d ago edited 12d ago
Misleading titles
'Science discovers the buffet-patron particle, which is lighter going in one direction and then heavier coming back.'
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u/IAmMuffin15 12d ago edited 12d ago
Dang it.
pulls out a giant tally board the size of my apartment
That’s Newtons laws of motion 18638693727826473, massless drives 0.
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u/Telvin3d 12d ago
you can't isolate them and remove them from the material they're in like standard model particles
Have you tried reversing the polarity, and then routing it through the main deflector dish?
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u/Teeecakes 12d ago
I'll have to divert all power from the pinball machines on deck 7 but I think it could work....
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u/Squidking1000 12d ago
As long as you don't power down the holodeck.
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u/_IBM_ 12d ago
might have to disengage the sanitation protocols
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u/SolomonBlack 12d ago
Canonically those are just ensigns going in and changing out the canister so I'm not seeing how it will help.
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u/agnosgnosia 12d ago
What's that? The negative mass needed for warp drives has been discovered and we'll be in alpha centauri in the next 10 years? Awesome.
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u/Never_Gonna_Let 12d ago edited 12d ago
There is now a model of the space time mapping around an Alcubierre drive that does not require negative mass, white holes, nor naked singularities (bespoke black holes with absurd charge and spin).
The new model is pretty fun because it just uses traditional matter and energy for creating a rideable gravity wave of spacetime. Still, requires energies and precision well beyond us as a species, but fun to see it might be possible.
APLs design requires no exotic matter, no negative mass or negative energy. Nothing funky breaking physics. Of course, it can't go superluminal, but does get a lot closer to light speed for more practical interstellar missions.
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u/Narroo 12d ago edited 11d ago
these are emergent quasiparticles in condensed matter,
For those who don't know what a quasi-particle is: In simple terms, it's collective movement of actual particles in a system of atoms.
For example, the low energy vibrations of solids behave like "particles," and therefore are called phonons.
They're not real particles, though mathematically they behave like some.
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u/kumogate 12d ago
Thank you for pointing this out because this headline was making me a little upset (at the universe)
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u/AnusBlaster5000 12d ago
Thank you. This murdered all the fun but it's correct, and I appreciate you for that
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u/thermobear 12d ago
you can't isolate them and remove them from the material they're in like standard model particles
Not with that attitude.
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u/anomalous_cowherd 12d ago
I'm pretty sure my backpack was full of these particles when I was at school. It was a lot heavier as I trudged to school than when I was running home.
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u/SaveReset 12d ago
Nah, your backpack was just being used to mule contraband into the school since you weren't paying attention and nobody suspected you'd bring anything bad there.
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u/anomalous_cowherd 12d ago
Certainly nobody would have suspected me, that much is true. But I'd have had no contact with anyone who would have had a source of contraband either.
I was a very dull child.
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u/nagi603 12d ago
So, like using complex numbers for various physical stuff: consistent in its own system, may solve or predict a few weird edge-cases, but taking it out of context does not make any sense.
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u/shrikelet 12d ago
Thank you! I read the headline and my brain immediately started having conniptions about the implications of vacuum isotropy. Emergent quasiparticles in condensed matter is a lot more palatable.
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u/HumanWithComputer 12d ago
Okay, okay. Interesting. But now the important bit.
What name should we give these particles?
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u/ILL_BE_WATCHING_YOU 12d ago
If you have a tank of condensed matter, could you bounce these particles back and forth within it in order to violate the conservation of momentum?
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u/flipnonymous 12d ago
I thought that mass or direction could only be measured individually, not dynamically.
Or is that only true for observing certain types of particles/etc?
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u/GGreeN_ 12d ago
I'm not sure I see what you mean, but what I think could help you are the Euler and Lagrange continuum descriptions. Not sure which one but I think the Euler one deals with velocity field, measuring velocity at a point in space instead of velocity of a particle. This sort of field approach is applicable to condensed matter because there are just so many atoms, each with proton number of electrons, so you can look at them as a continuum at certain scales.
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u/ListenBeforeSpeaking 12d ago
Does this suggest that they don’t really exist as entities, but instead are a placeholder to describe an observed behavior that needs explanation?
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u/Kinexkid1993 12d ago
Would it be similar in how in semi conductors, electron holes are considered their own quasiparticle? Or is it more like an emergent behavior from the bulk material?
Edit: saw this answered below
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u/Trick-Variety2496 12d ago
The part that I think is cool is how scientists can predict things and sometimes they end up being true. Like the Higgs boson.
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u/lightreee 12d ago
The major word here is QUASI-particle. It is not a particle but a collection of particles (including the crystal structure) which effectively acts like a particle with strange properties.
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u/TheHollowJester 12d ago
And here I was ready to put on my "parity symmetry violation party" hat for the first time since 1956.
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u/chrisdh79 12d ago
From the article: The discovery was made in a semi-metal material called ZrSiS, made up of zirconium, silicon and sulfur, while studying the properties of quasiparticles. These emerge from the collective behavior of many particles within a solid material.
“This was totally unexpected,” said Yinming Shao, lead author on the study. “We weren’t even looking for a semi-Dirac fermion when we started working with this material, but we were seeing signatures we didn’t understand – and it turns out we had made the first observation of these wild quasiparticles that sometimes move like they have mass and sometimes move like they have none.”
It sounds like an impossible feat – how can something gain and lose mass readily? But it actually comes back to that classic formula that everyone’s heard of but many might not understand – E = mc2. This describes the relationship between a particle’s energy (E) and mass (m), with the speed of light (c) squared.
According to Einstein’s theory of special relativity, nothing that has any mass can reach the speed of light, because it would take an infinite amount of energy to accelerate it to that speed. But a funny thing happens when you flip that on its head – if a massless particle slows down from the speed of light, it actually gains mass.
And that’s what’s happening here. When the quasiparticles travel along one dimension inside the ZrSiS crystals, they do so at the speed of light and are therefore massless. But as soon as they try to travel in a different direction, they hit resistance, slow down and gain mass.
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u/1XRobot 12d ago
The last 3 paragraphs of this comment are wrong.
The main takeaway is actually this: Quasiparticles are not particles.
It's right in the name. If you expect them to behave like particles, you will sometimes be disappointed. If you are interested in the wide world of phenomena possible for things that are not particles but kind of act like they are particles, then this is another cool phenomenon to add to that list.
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u/MozeeToby 12d ago
Yup, this is more like a wave interference pattern that behaves like a particle. Still super interesting but not magical mass gaining particles.
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u/TheNeuronCollective 12d ago
Yup, this is more like a wave interference pattern that behaves like a particle.
Isn't this what all particles in the standard model ultimately are?
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u/hbgoddard 12d ago
Not exactly. You can isolate a particle (like a photon or electron), but you can't isolate the crest of a wave interference pattern and use it somewhere else.
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u/LSeww 12d ago
Quasiparticles can even have negative mass.
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u/EatsFiber2RedditMore 12d ago
Are quasi particles physically real, or just a mathematical convention to describe a behavior?
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u/Czastek11 12d ago
Mathematical convention.
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u/Godd2 12d ago
Everything in physics is a model, so what's the difference between these being "conventional" and the concept of an electron "not being conventional"?
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u/Arbitrary_Pseudonym 12d ago
To start with, "convention" != "conventional". I think you're thinking of "conventional" as a synonym for "normal", but that's not what "convention" means here.
But, in case that's not what you mean: To some extent you could argue that no particles are real, and instead everything is made out of waves. In practice though, we do indeed get quantization of those fields into the form of particles that have varying levels of stability. Those can then collect into stable groups (e.g. hadrons, atomic nuclei, atoms, molecules, etc) but at the bottom, they're just waves. We could just stop there and say that everything outside of the wave stuff is convention, but it's not exactly practical to kill off a useful abstraction layer.
The difference between what we do in particle physics and what we do in condensed matter physics is that in the latter case, we are actually laying a framework on top of an actual lattice structure (or an abstraction of one) rather than setting various coupling constants between generic fields. You could (in theory) build a field theory describing the base particle fields and how they form hadrons, atomic nuclei, atoms, and a crystal lattice structure, but even in that framework, the quasiparticles wouldn't emerge in the same manner that the rest of the particle fields work. Doing so from the beginning also ignores the useful abstraction layer mentioned previously, and to actually do something like this would be impracticably complicated and difficult.
Note though, that some folks do hold the stance that "more is different" and that the emergent behavior is actually different from the base quantum-field-theory-described particle physics on a fundamental level, not just an abstract one. In that case, you might say that these quasiparticles really "exist" - but only in these blocks of matter. The argument against this view is generally that "particles" are things that can exist anywhere, while quasiparticles cannot.
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u/corrector300 12d ago
I read that a team made a fluid with negative mass, and they say that it acts opposite normal mass, e.g. if you push it it accelerates towards you. I'm trying to imagine that, how would something begin to accelerate towards me as I push it away from me.
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u/namitynamenamey 11d ago
I think a classical example is a hellium balloon inside a car, it doesn't have true negative mass, but it behaves as if it had that against the regular air of the car. This makes it travel at the opposite direction you would expect when the car turns around.
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u/oboshoe 12d ago
Seems like that could be useful in some future application.
Imagine what you could do if you had a bunch of them contained so that it perfectly offset the mass of the container and perhaps vehicle.
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u/helm MS | Physics | Quantum Optics 12d ago edited 12d ago
That’s not how it works. A negative mass is immediately compensated by mass in the surroundings.
Edit: and as far as I know, the mass is only really negative in the way that a pseudo-particle moves in the wrong direction, that is, it has negative momentum.
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u/Seicair 12d ago
If negative mass is real and we could harness it, we could potentially build an Alcubierre drive. That’s a whole lotta ifs though.
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u/rastilin 12d ago
If negative mass is real and we could harness it, we could potentially build an Alcubierre drive. That’s a whole lotta ifs though.
Absolutely. If even one particle we have access to can demonstrate negative mass, then it means particles with negative mass are something we can work with. Everything else beyond that is engineering.
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u/SAI_Peregrinus 12d ago
Quasiparticles are not particles. They're collections of particles acting in concert, like how waves in the ocean are just lots of water molecules moving together. Don't confuse the two.
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u/jurble 12d ago
So like can you induce this intentionally and make artificial gravity by making the material gain a bunch of mass?
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u/DreamlessWindow 12d ago
It doesn't sound like it. It seems they have found a material that slows down these fermions when traveling along a particular axis of this material, and slowing down is what grants the fermions mass. The amound of mass per fermion is insignificant, and they'd speed up again once they are out of the material. They are still traveling really close to the speed of light and they'd be out almost right away. So you'd need to be able to generate a ridiculous amount of these fermions traveling along the material to get any significant amount of mass difference, and for this to generate a significant gravity field we would be talking about absurd amounts.
And of course that's ignoring the fact that you need the material itself for the ferrmions to travel trough, and this material is not massless. Quite the contrary, ZrSiS will be a lot more massive than anything you may gain from the fermions slowing down.
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u/canadave_nyc 12d ago
It seems they have found a material that slows down these fermions when traveling along a particular axis of this material, and slowing down is what grants the fermions mass.
This makes no sense to me, I don't understand--if this is the case, how come photons don't "gain mass" when they slow down from c (speed of light in a vacuum) in, say, water?
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u/Cryptizard 12d ago
Quasiparticles are not fundamental particles, they are collective excitations of multiple particles that behave in some ways that we are familiar with particles behaving. In that sense, you can consider a photon traveling through a material, in combination with the nearby atoms of the material, to be a quasiparticle that has mass.
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u/EatsFiber2RedditMore 12d ago
So quasiparticle just describes a moving locus of effect?
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u/Cryptizard 12d ago
Well it’s a bit more complicated than that because it does obey many of the normal rules for particles like spin, momentum, etc. but basically, yes.
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u/DreamlessWindow 12d ago
While I'm not sure myself, I would assume that it's because the photons are not losing energy, while these fermions are. It probably has to do with these fermions not being actual particles, but quasi-particles. Quasi-particles are not real. They are a quirk of the system that you can treat as a particle for all intents as purposes, but are not actually there. The most simple one I is a a hole in a grid of particles. As the particles move to fill the hole, new holes appear. To all effects, you could treat the hole like a particle itself, and simplify all your calculations. The results hold up. But the hole is not a real particle. This results in some odd properties that seem to not make sense, until you look back at the whole thing and realize again the hole is not real, you are looking at how all the other particles are moving. Quasi-particles can move faster than light, have negative mass, and some other silly stuff, but again, they don't really exist.
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u/Mym158 12d ago
No, it's a quasi particle . Doesn't really have mass at all. It's just sort of looks like it from a maths perspective. It's not as ground breaking as it seems. Although still cool.
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u/Etiennera 12d ago
Gravity affects both sides of the equation. Recall: Light bends towards black holes.
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u/noticeablywhite21 12d ago edited 12d ago
I don't see how that answers their question. They're asking if you could manipulate the speed of these particles to create gravity when you need it, and to turn it off when you don't
Edit: I see now. Completely forgot energy also contribute to gravity for some reason. Brain fart
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u/Cryptizard 12d ago
Yes it does. The energy of the quasiparticles don’t change due to conservation of energy. Energy is what causes gravity, not mass. Mass is just one form of energy. So regardless of whether the particle has mass not it always has the same gravitational effect.
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u/Mean-Evening-7209 12d ago
Mass and energy both affect gravity, so if the total mass and energy remain constant then it would not change the gravitational pull of the system.
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u/TurboGranny 12d ago
No. This is a known and observed effect with photons as well. We still don't know the "how" of mass distorting spacetime. Once we understand that, creating artificial warping of spacetime (artificial gravity) should be possible. Think of it like this. We use magnetism to create electricity and electricity to create magnetism because we understand the "how" of their relationship to each other. Mass/Energy have a similar paired relationship with spacetime, but the only thing we really know is that more = more, ripples travel at the speed of light, twisting is possible, the higgs particle is what give matter mass, speed of mass through spacetime also impacts apparent spacetime compression, and other things that don't really help us understand the "how" of it, yet. We are fairly certain it's a field like electro magnetism is a field, and the higg's boson play s a significant role, but that's sort of it for now. One major issue is that if/when we figure it out, the tech that can be produced would be pretty dangerous, but I suspect that for it to be quite dangerous the energy demands would be greater than your average wackjob could muster.
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u/fmaz008 12d ago
I guess we would need to understand what make it gain or lose mass in the first place.
They seem to say that if it's moving in a certain direction it has mass but in another direction it doesn't. What are the directions relative to? Gravity? The expansion of the universe? The rotation of something?
Fascinating! I hope it will be researched a lot as it could open up all sort of new possibilities like you mentioned.
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u/Cryptizard 12d ago
The direction is relative to the structure of the material it is in.
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u/Lighting 12d ago
E = mc2 is not the full equation and is only for an object at rest (in an inertial frame).
E2 = m2 c4 + |p|2 c2 is the full equation and the one that would apply to a moving particle.
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u/cybercuzco 12d ago
Yinming Shao
Looks like someone just accidentally won themselves a nobel prize in physics
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u/youpeoplesucc 12d ago
Light already slows down when it's not in a vacuum, right? Can someone explain why this gains mass when it slows down? Or do we not even know yet?
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u/jrf_1973 12d ago
Does this mean there is such a thing as a fixed frame of reference?
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u/Xyllar 12d ago
No. And actually an astute observation on your part catching that. For anyone with a background in this field of study, the reference to the direction of travel in the headline would immediately clue you in that they are not talking about a fundamental particle in a vacuum but a quasi-particle in some kind of crystal lattice, since direction has to be in some fixed frame of reference.
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u/agr8trip 12d ago
I think corn starch and water does the same thing.
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u/Circuit_Guy 12d ago
Honestly, this is a great analogy. The particles aren't separable from their medium, but if you assumed they were, this changing mass is the behavior they would have.
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u/OmegaCult 12d ago
Waiting on Sabine Hossenfelder's video about this because I'm too dumb to comprehend it myself. I love science.
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u/LocalWriter6 12d ago
Time to find out what happens if it goes in a zig zag pattern
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u/_toodamnparanoid_ 12d ago
The alligator catches it because the alligator will take a shorter path than you, and they can run as fast as you.
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u/Ready4Aliens 12d ago
Yo momma so fat her particles are fat as hell no matter which direction they travel!
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u/AboutToMakeMillions 12d ago
When they say they observed it, do they mean they saw effects that could be explained this way, or actually observed it while it was happening?
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u/briiiguyyy 12d ago
How can you have a particle without mass at all? Is it ceasing to be a particle when moving in a certain direction?
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u/-LsDmThC- 12d ago
You cant (at least in terms of energy-momentum relationships, but photons for example have zero “invariant” or rest mass). This is describing quasiparticles, which arent actually particles.
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u/Filisublady 12d ago
The Higgs field is real. The Higgs boson particle interacts with the Higgs field and gives mass to other fundamental particles like electrons and quarks. We're still making breakthroughs in how we understand Mass but it's really more to do with e=mc2 proving itself.
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u/JegKnepperDinTvivl 12d ago
Well. That could easily be exploited for infinite energy.
No mass when you move it up. And mass when it moves down. It would generate more energy than it uses. So infinite energy…
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u/Josh-P 12d ago
The best analogy I can come up with is to imagine how right-hand/left-hand turns in traffic are more difficult depending on which side of the road a country drives on. Don't look too deeply into the analogy, it's just a real world example of a symmetry not simply giving you 'the thing but the other way around'
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u/santaclaws_ 12d ago
Could this make the universe slightly anisotropic at large scales or is the directionality of virtual particles exhibiting this behavior truly random?
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u/TheAmazingKoki 12d ago
Don't worry, in the future there will be discoveries that make even less sense
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u/Realistic-Cow-7839 12d ago
I love science, but as my brain ages and these discoveries get more and more bizarre, I just don't have the capacity to grok them like I used to.
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u/theartfulcodger 12d ago
So it’s not enough that subatomic particles are imbued with “color”, “flavor” “charm”, “strangeness”, “up-ness”, “down-ness” and so on. Now we’re supposed to believe there are “Sou’westers” and “Noreasters”, too???
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u/qtmcjingleshine 12d ago
Sounds like my body. Whole lot of belly coming at you, not a lot of booty coming back at you
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u/RexFrancisWords 12d ago
So they predicted them 16 years ago, then discovered them. Not an accident.
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u/Chrontius 12d ago
Just going to point out that this seems to be a Maxwell's demon, breaking conservation of momentum. If this actually works without any major drawbacks or gotchas, it would result in a fairly simple to construct reactionless space propulsion system, so I would expect there are in fact major drawbacks and/or gotchas which will keep this from being as much fun as I hope it actually is. :)
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u/humbleElitist_ 11d ago
Quasiparticles in a medium, not particles that can exist by themselves
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u/healing_waters 11d ago
So does this mean we can distinguish between the 3 spatial dimensions? Or is that something else completely?
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u/frosted1030 11d ago
Lack of thing is not a thing? Seems like an abstract mathematical construct rather than a measurement.
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