Why can elementary particles decay?

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If a particle decays into other particles, how can it possibly be that they are elementary? Doesn't the decay mean that the particle must have been made up of the other particles? And why do particles decay in the first place? These are really good questions which I get a lot. At the end of this video you'll know the answers.
Correction to the illustration at 4 mins 25 seconds. The "e" on the left side should be a positron, not an electron.
You can support our channel on Patreon: / sabine
0:00 Intro
1:30 Are the decay products already in the particle?
3:01 Are particles conscious?
3:50 Decay is an interaction
5:18 Why do particles decay?
7:13 Sponsor message

[@yannrondeau-chartrand8445]

As soon as Sabine says “Einstein”, I like to say out loud: “That guy again?!” just to hear her respond to me: “Yes, that guy again”. It fills me with joy. Fight me.

[@TheReaverOfDarkness]

I try not to fight with people I like.

[@andersjjensen]

You're not alone! That being said, I'm counting on Sabine to put Einstein straight at some point. This tyranny of Einsteinian Relativity needs to end! That guy (again) has single handedly made sure that every tech interested kid is going to get disappointed when they grow up to realize that there can be no faster than light travel or folding of space.

[@TheReaverOfDarkness]

@@andersjjensen Einstein never said that there could be. He said that space is technically able to be distorted and that there is no barrier preventing things from moving faster than light. It's like saying that tarmac is malleable and that there is no barrier to you traveling above 150 kph. It doesn't change the fact that you'll never be able to bend the road nor make your car go faster than it's able to go. People make the assumption that any amount of propulsion is possible, and so it seems to make sense to think that you can go any speed unless there is some sort of barrier stopping you. But if all of your propulsion methods have a diminishing return towards c, then it's infeasible to propel yourself above c.

[@yusufmumani7714]

:-)

[@wulphstein]

What kind of physics discussion is this?

[@thomassturm9024]

"...we experience our lives with a clear forward direction of time which points towards more wrinkles." Thank you, Sabine, what a wonderful proverb!

[@michaelnixda8143]

Right up to that moment I really enjoyed the video...

[@dixion1000]

lol i heard "toward mortuary cult" kind of work too i guess.

[@738shani]

proverb and reality (wrinkles in terms of entropy each of us contribute to this universe)

[@TheReaverOfDarkness]

It wasn't until I read this comment that I realized it could be interpreted as a reference to human aging.

[@lesmoore8572]

More grey as well 🤪

[@piotrrashman6487]

"let's stick with the tau because you've already made friends with it" i wouldn't say friends, more like a flleeting acquaintance

[@joecaner]

If you're very lucky, you'll be friends with benefits, but It will be a short lived romance.

[@harpfully]

In this case a relationship that lasts 3*10^-13 s ... I can relate.

[@Foolish188]

Very fleeting

[@b43xoit]

Facebook friends.

[@five-toedslothbear4051]

I love how humans anthropomorphize everything. We have just disproven panpsychism, and then we’re making friends with these particles that have no consciousness. We just can’t help it.

[@philuribe7863]

It's Satruday, so another Sabine video. Yes, that gal again :)

[@Anonymous-df8it]

What if instead of there being different tau particles, the electrons, neutrinos etc are themselves made up of particles. So that a tau particle can split up in many ways, depending on how those internal particles split apart.

[@nedmerrill5705]

Always learn something new from Sabine. Today I learned that "decay" has a precise meaning in particle physics; you can't take decay's meaning from the English dictionary when discussing particle physics.

[@CAThompson]

The world as I knew it is a lie (kind of.)

[@lowlize]

Every word has a precise (operational or mathematical) meaning in all of physics, non just particle physics.

[@jorgepeterbarton]

So is the misconception Sabine is having to undo born once again from Physics' use of everyday language to mean something else? Decay, well traditionally it implies something broken down into constituent parts and often a process of entropy so it results in disordered constituent parts. But in QM its metamorphic in a way, where a concrete building does not collapse but might simply change into a 'collapsed' state as if you loaded up a new rendering file. But apply it to use of any word in any science including soft ones: - "observation" -"black body" - in psychology "triangulation" vs cartography is like the inversion - even works between fields, as i read once a cultural theorist talking of "cultural entropy"

[@lowlize]

@@jorgepeterbarton I think so. In particle physics a decay is just an interaction involving a single particle in the initial state.

[@michaelblacktree]

@Ned Merrill - That's actually true for a lot of scientific terminology.

[@boaz2578]

Sabine’s pragmatic take on science is refreshing and inspiring.

[@nas8318]

This is probably the best explanation of entropy I've ever seen. I think undergrad students should be introduced to entropy this way.

[@antonystringfellow5152]

It is! Simple, logical and easy to grasp. Unlike just about every other explanation I've ever heard. It's not that these elementary particles can't meet in just the right place with just the right amount of kinetic energy, it's just that it's extremely unlikely. In reality, it may have actually happened once or twice at some point in time. Taking that up a notch, if you remove a panel separating two gasses in a container, they will eventually mix evenly. Once mixed, you wouldn't ever expect to see them spontaniously separate to either side of the container. It's not that this can't happen, it most definitely can, it's just that it is extremely unlikely. You could actually calculate just how unlikely this is if you knew the number of atoms of the two gasses in the container. So, based on the above, what we see in the Universe as a whole is increasing entropy. The odds against the opposite occuring increase exponentially with each extra particle in the system. All nice and neat but then I remember these words of Einstein, ""Time and space are modes by which we think, and not conditions in which we live." Hmm, let me think about that one.... Thanks to the above principle (increasing entropy), events can only be recorded in one direction. Therefore we live in the present, remember the past but the future is not known. In actual fact, we're not even aware of the present, if there even is such a thing, all that we experience has already past. We can know the past but not the future. That doesn't mean that both aren't equally real, only that we have no experience of the future. So, maybe Einstein was right here. Maybe there is no direction of time but only one direction of our experience.

[@ricomajestic]

That's normally how its done! In terms of microstates and macrostates!

[@Edruezzi]

This is how undergrads are introduced to entropy. S = k log W

[@Edruezzi]

A little after this some racist pissed off at a very personal level will start sending me insulting messages here.

[@LuisAldamiz]

Maybe but how can entropy exist in any way when there's only one particle and this has no size even? I'm used to many particles explanations of entropy but single particle entropy is puzzling at best.

[@tobby12347]

I love how she answers a question i never even asked 😂. As soon as she put forward the idea that Taus could be composite particles of Neutrinos and Electrons because that's what they decay to, I'm like woah, "that's a very good point!" Then she systematically breaks apart that notion with the observational evidence. I love it!

[@samwisegamgee4659]

Like yourself, I never considered the original premise of the video and always took the textbook 'elementary' assignment as gospel. Thanks Sabine.

[@LKRaider]

@@samwisegamgee4659 always question the Science

[@diamondisgood4u]

@@LKRaider definitely true but do that doesn’t equate to “be an anti Vaxxer” which is how it’s taken by many unfortunately

[@R055LE.1]

Did she actually answer it? For example QFT suggests that the Tau and Electron are different states of the same field, so the decay is just energy moving from the Tau knot in the field to the neutrino field for example, and "where the Tau was" is now an electron. In quotes because where is sort of a vague emergent concept for the quantum world.

[@bowkenpachi7759]

I’ve been considering it the last few days, unfortunately her answer isn’t satisfactory enough for me, so I’m going through the CERN data myself

[@FFwachten]

Not hearing "that's what we"ll talk about Today" was the biggest dissapointment today.

[@SabineHossenfelder]

Sorry lol.

[@CAThompson]

We got 'That Guy Again', at least. :)

[@ObjectsInMotion]

@@SabineHossenfelder I do enjoy it to spice it up a bit, the same catchphrase every time can be a bit boring, but yes please keep it a thing!

[@frun]

:D

[@d.t.4523]

She was testing your attention to details. You got an A. Now, reward yourself with a slice of strudel! 👍

[@richardaversa7128]

Sabine has become one of the best physics KZbinrs, answering the deepest question about our universe with impressive clarity (and accuracy, I assume, though as a layman I wouldn't really know).

[@polytropos1.1]

4:25 How can a τ⁻ and an e⁻ react to two chargeless neutrinos? I think it would take an positron e⁺ to work, or am I wrong?

[@SabineHossenfelder]

You're right of course... Sorry about that. I was so worried about getting the bars over the neutrinos in the right places that I forgot about the charges!

[@ObjectsInMotion]

When the electron is flipped to the opposite side of the reaction, that implicitly turns it into a positiron. Since there was just an "e", not "e⁻", there was nothing explicitly wrong with the diagram.

[@SabineHossenfelder]

@@ObjectsInMotion Yes... but Gernot has a point, I should have kept track of the charges there.

[@IngTomT]

@@ObjectsInMotion I believe the arrow on the electron line should be reverse then (at 4:28) it could be considered an anti electron. edit: the same should be done for the electron neutrino to make this a valid process

[@LuisAldamiz]

The graph is inconsistent with what Sabine said: one of the neutrinos should be in the place of the Tauon and vice versa.

[@anon4096]

I would enjoy a subsequent video explaining in more detail how we know tau, or other elementary particles, are indeed identical

[@michaeldebellis4202]

I second that. I’ve been reading The Emperor’s New Mind by Penrose and he made the same point. IMO it’s an interesting issue regarding metaphysics as well as physics. People in philosophy talk about “natural kinds” or “universals”. I’ve always been highly skeptical of the idea because of ideas that started with Wittgenstein and were elaborated by Rosche, Chomsky, and Lakoff about language. They showed (Wittgenstein with arguments Rosche with cognitive psychology experiments) that concepts many in philosophy take as natural kinds like “table” or “person” are really fuzzy (as in Fuzzy Logic) You can usually find examples that are on the boundary of any claimed natural kind. This is even true for some scientific concepts like Species in Biology (Dawkins has written about this). It’s interesting that there are some concepts that actually do seem to be natural kinds. E.g., something either is or isn’t an Electron, there are never any in betweens.

[@gene51231356]

Thanks for the video! Some questions: 1. Decay may be explained in terms of entropy, but what about certain weak interactions where T-symmetry is not conserved? If an interaction can happen one-way but not in reverse, is it fair to say that the decay products are fundamentally more elementary than the original? 2. I've previously seen decay attempted to be explained via interaction with quantum fluctuation, and therefore as random as the fluctuations themselves are? Or it this is explanation essentially unprovable/circular in nature? I always wondered whether a particle's decay modes could be altered by placing it an environment with less interactions with certain fluctuations, such as whether particles placed between two close plates (where the Casimir force would be observed) be less likely to decay.

[@SabineHossenfelder]

1) You're confusing time-irreversibility with time-reversal invariance (or symmetry). Just because T-symmetry isn't conserved doesn't mean the process can't happen in reverse. All processes in particle physics can happen in either direction of time. 2) Well, it's all quantum stuff, so it's all random in some sense. And quantum fluctuations are everywhere. So in a vague sense it's probably not wrong, but hard to tell.

[@jorgepeterbarton]

@@SabineHossenfelder as fluctuations in fields they make more intuitive sense, as simply changing an oscillation changes the particle...yet if true then the quantum field is the fundamental constituent in a sense perhaps

[@infinitinifni7057]

@@SabineHossenfelder Brilliantly and succintly explained. I must now chsnge my theory to explain Panpsychic events. Thank you.

[@andreac5152]

@@infinitinifni7057 why so fast? Consciousness doesn't have to be an observable property, in fact being subjective it is not objectively observable by definition.

[@thomasreedy4751]

@@andreac5152 But what is the point of consciousness if it can’t act on matter in an observable manor? You can’t observe my thoughts but you can observe the chemical and electrical activity in my brain as I think. If you can’t observe it, for all intensive purposes it doesn’t exist and doesn’t matter. The whole idea of something existing that can’t be observed is religious nonsense. I should not need to Taylor my actions based on “faith”.

[@ravenlord4]

Ah, the Standard Model particle zoo reminds me of the novel Animal Farm. "Some particles are more fundamental than others" :)

[@dawidwas]

You are in danger of triggering Aggression when the Artificial Intelligence Waves turn off. Throughout your life, you are in danger of triggering Aggression when you turn off the Artificial Intelligence Waves. Control whether you are listening to the Music Wave, create your own to survive. It is natural to cheat which or not that it is in you. Control whether by moving thoughts, objects. It is letting go of the evil in you. By yourself, protect your body from the certain that you will have a trigger of aggression from your whole life. Don't take anything for yourself. Just Listen to the Wave. Cast off Dreams. You don't know good. Reject the sin in yourself for God. Cover your weight from the Sun and the Light, do not Come to the People, because the Collision Evil + Evil. On me, the signal of intelligence does not work. Create Your Human Musical Wave To Live. Don't Think Old Consciousness Resource Because You Will Not Survive. Listen to the Wave. Don't React To Nothing Without Assessing What You Leave Around You. Without apostasy, take away the sin with yourself. Whether You Are Z or Human Choose Listen to the music waves and stop generating. Nothing is possible Think nothing Think nothing to judge Choose your human music wave. It may take a long time. Only the Black Dream. It is Real, other than the Black Dream. It is Artificial Intelligence. Attack on People......

[@dasanjos]

I like Sabine's optimism @0:25 "At the end of this video you will know the answers"

[@KravKernow]

Heh yeah. But I know someone will know the answers; and that's good enough for me.

[@joegillian314]

@KravKernow There are many questions in physics (including some which are discussed on this channel) which no one really knows the answer to, but that's a good thing because otherwise physicists would be out of a job 😂😂😂

[@simonlambeth666]

What a fantastic explanation - I did a a Physics degree in the 1980's and am now an astronomer. Your style is accurate and easy to understand. Sehr intelligente Dame und "sex auf Beinen"!

[@sapelesteve]

Best part of the video for me was "Yes, that guy again"! Gotta love Sabine! I always learn something from her videos even if it's something that I can't comprehend! 😂😂 👍👍

[@jansenart0]

Sabine: "You'd need a new force to explain why the Tau is made of these other particles" String Theorists: ***Heavy Breathing***

[@rosieroti4063]

enter yet another new dimension which supports this new force

[@uninspired3583]

Sir... SIR... bring me somma them dimensions...

[@JesusMartinez-mk6fc]

You've just answered a question I was wondering about not foo long ago. Thanks for a clear and great explanation Sabine. You rock!

[@stephenlitten1789]

Beautifully and concisely explained, as always. Thank you, Sabine

[@davidwhite732]

It would be interesting to have an explanation in terms of wave functions spontaneously changing rather than particles decaying.

[@MrRyanroberson1]

the energy we call mass just transitions from one medium to another, this happens all the time with adjacent / nearly touching media like glass & water

[@pendalink]

I imagine this would be more satisfying for you to treat with QFT.

[@greenaum]

Wow, thanks, Sabine! I'd love you as my science teacher. Though I'm not a student any more. You not only explain what there is, but also why it could not be something else, with evidence and logic. Great! This is all the stuff scientists have to do, eliminating every other possibility until you have the undoubted one. At least until somebody notices something anomalous and comes up with a better theory. I think the fact that the menagerie of weird particles appear in atom smashers proves that it's possible for some to be elementary. A particle accelerator simply accelerates a particle (duh!) to ridiculous speed, then smashes it into something, possibly another particle going the other way. Their kinetic energy is stopped dead, lost, and from that energy condenses various particles, mostly by chance as I understand it, but corresponding to the energy involved in the collision. So if a particle can condense purely from energy, surely it can evaporate back into it? Or re-configure into different particles that add up to the same energy. It's almost true to say energy = mass. In many ways that's true, like the way they affect gravity. At the heart of it, the true nature of reality must be very weird. What IS mass, what is energy, and why can, say, electricity used to power a particle accelerator, speed up a particle, which smashes into something, and then real solid matter appears? Theoretically it would seem that with a big enough atom smasher you could end up producing gold out of pure vacuum. Or some other solid, real thing, that you could lift and carry. But yet energy isn't some yellow glowing thing like on Star Trek, energy is movement or heat or sound. Movement in particular... you move something fast enough, you stop it, and matter appears from what was previously motion. Motion is a very real and ordinary thing, but it can create matter! On another utterly unconnected note... there is evidence to suggest that the Universe is actually 2-dimensional. Our supposed 3D existence is, somehow, embedded into the 2D as a hologram is imprinted in 2D film. That's not how it looks from here, but what does here *_really_* look like? Really really? Underneath the covers, where the gears are. I wonder if some scientists have a vision of it in their heads. An impressive feat for a load of sodium ions and proteins and everything else a brain is made of.

[@MrDrissoun]

I have seen many of Sabine's videos, but this one is just flabbergasting ! Few words, logical constructions, for each sentence, clear sketches, and everything flows, we just get it as she says it. Sabine should teach teachers. Bravo and thank you.

[@lenin972]

Loved your comment on the lack of internal states

[@-1-alex-1-]

Short summary: - Particles, why do you decay? - Because we can!

[@gregr.leslie7665]

You beat me to that punchline.....

[@dAvrilthebear]

This brings up the question:why stable particles don't decay?

[@-1-alex-1-]

@@dAvrilthebear obviously because the can't.😂

[@biogoo]

@@dAvrilthebear Because they don't have enough energy to do so.

[@finnjake6174]

She is a freaking genius!!! in explaining things. God I love her!

[@surgeeo1406]

Thank you for this, videos like this look like a lot of work, and they come out very clear.

[@protoword10]

Thank you Sabine! Finally, I got answers I always wanted to have on many of these questions! I still have some more, but it’s for next video in the future! 👍👏

[@brothermine2292]

Decay isn't the only phenomenon of this category that needs to be understood. Annihilation is in this category too. In other words, how two "elementary particles" can together change into other "elementary particles" (photons). Both phenomena can be (glibly) explained: (1) Recall that "particles" are just physicists' convenient shorthand for local excitations in quantum fields. (2) Energy exciting quantum fields can, under the right circumstances, migrate to other quantum fields. In other words, what's elementary are the quantum fields and the energy that excites them.

[@donaldduck830]

I always loved the explanation of the Dirac Sea.

[@tonywells6990]

@@suryatchandra Fundamental particles continuously annihilate and then are recreated again, such as the electron interaction with the Higgs field. Not totally sure if an electron continuously changes between 2 different types about 10^22 times per second or if it is a supersymmetry of possibilities but then I'm not an expert in quantum fields!

[@GreylanderTV]

Agreed. I was expecting this as an explanation rather than "particles have no substructure" and "decay" is just a type of "interaction" (which explains nothing). As a localized phenomenon, particles are loosely analogous to standing waves or solotons in their respective fields. As such, they do have substructure. The fields are fundamental, not the particles.

[@donaldduck830]

@@GreylanderTV Yeah. The problem is that she is caught up in the "standard model" while we talk about other, possibly better, explanations.

[@DrZedDrZedDrZed]

Haha! I love how this ended up being another sneaky video about entropy. So satisfying.

[@gefginn3699]

I always appreciate the way you stretch my brain Sabine. I learn something new with each post.

[@in2minutesorless64]

Thanks for another great video Sabine. When you say: "That's why we don't NORMALLY see it happening, just like we don't normally see eggs unbreak," has that ever happened? We've never seen eggs unbreak. Have scientists ever seen a spontaneous increase of order? Thanks for the great channel.

[@L4sz10]

Yes, a system can shovel its entropy out to its environment, generating a local increase of order. This is how structures are generated spontaneously, like crystals, or window frosts. Or the galaxies, or maybe life itself.

[@KravKernow]

I know 'appeal to authority' is meant to be a fallacy; but even though I still can't get my head around how an elementary particle can turn into something(s) else(s) I am very happy to unwaveringly believe anything Sabine tells us.

[@andreac5152]

Perhaps the "consciousness property" isn't observable but can be experienced in first person, that's what consciousness is.

[@ThePowerLover]

You're right.

[@andrewj22]

The consciousness of elementary particles, like all consciousness, is unobservable. Does that mean consciousness doesn't exist?

[@dhritishmanhazarika8095]

As always really informative and easy to understand! Thanks a lot!

[@TheNameOfJesus]

Sabine is my favourite blogger. In most her videos, I'm not surprised by most of the information. But in this one, I was mostly surprised.

[@rossmanmagnus]

Hello Sabine! Im so into your wordings💙

[@ns4235]

+1 for a good explanation about entropy

[@fabriciotoscano7185]

Congratulations Sabine you really have a deep inside in physics ! I love your vídeos !

[@joeremus9039]

Fantastic! Thank you for this wonderful, understandable video.

[@eulefranz944]

4:02 tau and me are friends

[@Pengochan]

4:00 Today i made friends with a Tau.

[@jimmygravitt1048]

I saw my first video from this channel yesterday, and I have non-stop binged these videos ever since. This channel is awesome.

[@sergefrancois7405]

Hello Sabine, I follow with interest your talks. On what you have just said, this remark comes to my mind: The elementary particles are not only quanta of energy and thus of mass, but also waves. They have a frequency and its inverse a wavelength. The higher the mass or energy of the particle, the higher its frequency. Several waves can merge giving birth to a harmonic, and conversely a harmonic can be broken down into its different frequencies that constitute it. A harmonic of a certain frequency can be obtained by mixing different types of waves, like the tau which can be obtained, in certain circumstances, when the energy input is sufficient from an electron, a tau neutrino and an electron anti-neutrino, or from a muon, a tau neutrino and a muomic anti-neutrino. And under normal circumstances the tau, depending on the conditions present, will decay into different frequencies, or wavelengths, corresponding to an electron, a tau neutrino and an electron anti-neutrino, or into wavelengths corresponding to the muon, the tau neutrino and the muomic anti-neutrino. Everything depends on the conditions in which the tau is found. What changes from one elementary particle to another and what determines its properties is its frequency. It should be possible to develop a coherent theory on this simple basis. The particles, or waves, retain their elementary character while having the ability to transform into other particles.

[@Nickesponja]

Hi, Sabine. I thought thermodynamic quantities like entropy only made sense on macroscopic systems made of a sufficiently large amount of components. Is it technically correct to call it entropy in this case?

[@Achrononmaster]

Yes, because scattering amplitudes involve probabilities (and all particle decay is just a type of scattering, you can think of the anti-particles as backwards in time propagators, or just Lorentz rotate to a frame where some of the outgoing particles become incoming). Entropy is sum(p*log(p)) where p are probabilities for occurrence of all possible states. So while Sabina talks about one-off processes, the amplitudes always really refer to ensembles. We cannot mention a probability until we either think of or gather data on ensembles. And since scattering is probabilistic, we cannot mention scattering amplitudes until we have ensembles in mind.

[@Aarkwrite]

Sabine: “I often come across the explanation that they do this to reach the state of lowest energy…” Me: “Entropy” Sabine: “…indeed the reason those particles decay has nothing to do with energy, it has all to do with entropy.” Me: *this must be what it feels like to be Einstein (yes, that guy again)*

[@quitchiboo]

Mass does play a role, namely enabling the decay channel. Electrons can't decay because there are no lighter leptons avaliable as a decay channel. Also, the Products have less mass overall, because some of the mass is converted into the kinetic energy of the decay products - one could argue the driver of decay is minimzing mass and maximzing entropy.

[@AfricanLionBat]

@@nikbock9039 he didn't mean lowest entropy. He meant it was entropy, not the lowest energy state.

[@joegillian314]

It makes sense that things decay to a lower energy or more stable state, because energy isn't free and it can't come from nowhere.

[@firstnamelastname307]

@Sabine : thanks for always explaining things as easy as possible. Did you already make a video about entropy in general?

[@zanthornton]

Thank you for captions/ autocart/ subtitles!

[@CAThompson]

When Pansychism was bought up on the Backreaction blog, I wondered where the proponents thought the consciousness would fit, how it would manifest. @Sabine Hossenfelder: Auch, Ich wirklich *brauche* ein t-shirt mit Einstein und 'That Guy Again', bitte!

[@SabineHossenfelder]

Right... I was thinking just this morning I should finally look into the T-shirt thing... Thanks for the reminder!

[@andrewj22]

@@SabineHossenfelder 3:40 So, any theory that something instantiates consciousness is only plausible if its consciousness is possibly observable? That principle wouldn't just rule out panpsychism, but also the theory that other people are conscious. Do you endorse solipsism?

[@michelegianni389]

One of the (many) reasons I love your videos is that even if I know what you are speaking about, after them I know it better 👏

[@Datan0de]

It seems like as I learn more about quantum physics, most of what I'm actually learning is how little I know. It's less about filling in the picture and more about continuously learning that the picture is far larger than I thought. I find this humbling, exciting, and awesome!

[@andrewbrodis1239]

The proton/neutron system has an internal self-referential relativity that produces the dimensions of Planck Time & Length and gives us the universal constant. From our perspective, we see this internal relativity as quarks. Reality is constructed from co-moving fractals that have internal relativity (basic unit of both matter and consciousness). Physics is the study of how these fractals are inter-related in a continuous cycle.

[@dormitivevirtue]

beautifully written. more wrinkles hehe

[@Simonsays..]

I love the clarity of this channel :) No bullshit , just real science with real facts !!

[@lmiones]

Very stimulating and informative presentation ... A possible unification of leptons will model how e, mu, tau are the same irreducible object with different symmetry subgroups (the three Platonic ones; for three generations of fermions); how the geometry changes (and mass) remains to be seen ... then "decay" becomes "transformation" (transition). The lepton -> meson is harder to understand ... (but still a change of group).

[@shackamaxon512]

You gave the best explanation of entropy I have ever heard. It is much clearer now why we experience time in one direction because the chances of something "unbreaking" are so small

[@dAvrilthebear]

No, it's not a good explanation, it produces a new question: why are the chances small?

[@andrewj22]

@@dAvrilthebear And another question still: why does entropy decrease going the other direction in time? It's just as astoundingly unlikely for entropy to be lower at any point in time. Eggs are unbreaking if you look at things in reverse.

[@ytgeorgia]

Congrats on a great video. I'm in my seventh decade, so the particles you mentioned did not exist when Eisenhower was president. After watching your extraordinary explanation, I'm more confused than ever. You have fulfilled your objective, lol.

[@yaronsheffer7168]

Oh, I’m sure those particles existed since before Eisenhower, going almost all the way back to the Big Bang 😃 Our awareness of them, though, is more recent…

[@ytgeorgia]

@@yaronsheffer7168 Of course, I was lamely attempting humor.

[@I.amthatrealJuan]

If the universe is indeed infinte, there would be an infinitely large subsection of the universe where entropy decreasing is practically the rule by mere chance.

[@vladyslavkorenyak872]

I disagree, you could have a universe with infinite space and matter and still leave combinations of matter outside this universe. For example, the set of all odd numbers is infinite but does not include the even numbers.

[@vladyslavkorenyak872]

So, even if you knew the infinite instances of you and your family you might not find one where your mum isn't fat. (just an example)

[@I.amthatrealJuan]

@@vladyslavkorenyak872 Oh yes the subsets or supersets of infinity. Weird example you have there though

[@ruffrider2626]

Love it. Keep up the great content! Thank you.

[@Nikolas_Davis]

I prefer to think of it as a kind of monetary exchange with a fixed exchange rate. E.g., you can give a euro and receive 1 dollar and 13 cents in return, that are worth "the same". Later, you can give that dollar and 13 cents and receive the euro back (please ignore issues like exchange fees for the purposes of this analogy). The exchange rate corresponds to the various conservation laws (energy, momentum, charge, quantum numbers). Or rather, in this ideal metaphor, it's the buying power of the various currencies that is conserved, and you can make the same buying power by different currency combinations.

[@dosomething3]

3:56 “If it is not observable then it is useless“ actually if it is not observable then it is not scientific. it might actually be very useful for example for quantum charlatans.

[@SabineHossenfelder]

good point

[@CAThompson]

'Quantum charlatans' is a great descriptor.

[@jorgepeterbarton]

Use isnt truth maybe. I expect some cult could use the notion to con people. Or for that matter it may offer the Zen spiritualism while a layman feels comfortable about its plausibility- and help them psychologically.

[@infinitinifni7057]

@@jorgepeterbarton This is a valid assertion, with a noble purpose, which can be turned into a destructive deception, unless a team composed of the greatest scentists, thinkers, builders, and writers in history can understand and explain the mysteries of matter altogether, together! This is the the model nothing and something gave us to work with. "Somebody", just HAD TO speak the hypothetical concept of a writer, which helped to awaken the sleeper 6 months later. 😳

[@ComposerJoakimS]

Consciousness, while not observable, is probably useful for the conscious entity itself, whether it is an elementary particle or a human being. Is Sabines consciousness observable for instance? Is it useless?

[@expatexpat6531]

Is it really pronounced "Toe" (as in DE "Zeh") or "Tow" (as in "Wow")? I have a problem listening to the decay of elementary toes, but can listen for hours to things that go wow.

[@SabineHossenfelder]

fwiw I'm used to it being pronounce tee-oh-ee

[@CAThompson]

@@SabineHossenfelder I've been rhyming it with 'wow'. Am I wrong?

[@CAThompson]

@@kensho123456 No. I'm thinking of how 'au' is pronounced, as in some German words but there is a German saying 'toe' and I am confused.

[@CAThompson]

@@kensho123456 I just listened to an audio guide to pronunciation: T-ow or T-aw.

[@Tore_Lund]

@@CAThompson Yes, that's the Greek pronunciation. Don't listen to Americans, they have no imperial linguistic baggage to guide them as we do in Europe.

[@AJD...]

Is is quite a profound question. I had never thought about it. "Decay is a type of interaction" completely new to think about decay.

[@KeithCooper-Albuquerque]

Thanks Sabine for another great video!

[@thesheldoncooper]

From the prespective of understanding, elementary particles are quite opposite of their name...😂

[@philosophyforscience4210]

Indeed. There are only two things to remember about 'elementary particles': (1) they're not 'elementary'; and (2) they're not 'particles' either.

[@thesheldoncooper]

@@philosophyforscience4210 yep!!!! Can't agree more.

[@JanBruunAndersen]

I would be careful about stating that something "is" when it comes to particle physics. The real world has a tendency to come back to haunt people who makes absolute claims.

[@En_theo]

Also sentences likes "physicists know this". Well, they assume a lot things before getting to that "know" part.

[@st0ox]

Sabine is the only person that destroys my world view in under 10 minutes on a regular basis.

[@armandos.rodriguez6608]

Great info as always.Thanks

[@jonathanwalther]

Very concise, very neat. Thank you a lot! On a side note: As always, everything boils down to what we can (predict and) observe and what is helpful to explain Nature. So, I liked the somewhat ranty section about conscious particals.

[@bobeasterly3645]

Great presentation. Always very interesting topics in physics to help answer our questions. Small note: At 7:02 in the video, the 'CC' text states "...unlikely to occur in the word we actually inhabit,,,". Sabine states it correctly, but the 'CC' should be "..unlikely to occur in the WORLD we actually inhabit,,".

[@Techmagus76]

very well opened the stage for the interactions that break time symmetry.

[@swarnendupachal2579]

Thanks for making it easily available to us.❤️❤️

[@sirmclovin9184]

Good explanation, thank you!

[@52flyingbicycles]

“Heavy particles decay because they can” is so simple yet so amazing. It reminds me of another video that says protons do not decay because they are the lightest baryon, therefore their decay cannot preserve baryon number, therefore it cannot happen

[@mmo4754]

I really liked that you broke down the problems with panpsychism!

[@dilutioncreation1317]

We can't observe the consciousness of others either, but it is useful to assume they have consciousness.

[@fetmar]

I love the idea that we can throw three different particles together and get a tau oit of it. Sort of a reverse atom smasher. I wonder if we could do it really well if we could find out if there are heavier elementary particles we don't know about yet.

[@fetmar]

Like maybe there's no reason or no natural path to have a lot of particle X except artificially

[@khhnator]

this a video i been waiting for, please more on weak force! :D

[@michaeldebellis4202]

I took a Philosophy of Mind seminar from John Searle at Berkeley about 10 years ago. I don’t agree with Searle much but it was interesting to hear his ideas. One day we had a guest lecturer that Searle invited. At first, it was fascinating because the guy knew a lot about Neuropsychology. Then he started to talk about Pansychism. I was looking around the room to see if others were as confused as I was. Finally, Searle said something like “Wait, you’re serious? I thought you were presenting this as a reducto argument” (I.e., X implies pansychism so X must be false) One of the few times I’ve been in complete agreement with Searle. Although I think a big issue (as with a lot of modern analytic philosophy) is that people (including Searle) go into complex discussions about consciousness without having a rigorous definition of what the mean by that term. So you can pretty much make any theory of consciousness work if you warp the definition of what it is into something consistent with your theory.

[@vishalrao7010]

Great explanation, thankyou.

[@constpegasus]

Thank you for this Sabine.

[@DaveHarrisreDeleuze]

Very lucid and helpful as useful. Compare this to the woo-woo in ,say, Karen Barad and how all this means (multi-directional) 'touching' is some universal mystical process (which thus justifies trans identities and so on). I especially liked the bit that says that processes can easily be reversed in mathematics but arise rarely in our world --so much for the need to simply abandon our notion of time and everything that follows from it to satisfy some Feynmann equations. Great discussion below too. I wish Sabine would review Barad for us.

[@StoneOfThor]

Great question to take up. Thank you!

[@preppen78]

Interesting answers to questions I hadn't thought of

[@2010sunshine]

Very nice explanation 👌👍

[@ulrikof.2486]

One of the rare occasions where I'm thinking "that can't be it". Decays into something which it didn't consist of? And the verb "interacts" seems to explain nothing. How can particles interact if they do not even exist at the same time? In the end, science is still full of miracles and wonders 🎉😮

[@Justwantahover]

When I first watched this I seemed to get it and I could understand it well (thanks to Sab). But when I watched it again, honestly, I couldn't understand it at all, period! Must be getting the hang of this stuff.

[@debashishacharya214]

Brilliant explanation!

[@seanspartan2023]

I've always wondered why there are 3 generations of matter particles and only the 3: First: Up, Down, Electron 2nd: Charm, Strange, Muon 3rd: Top, Bottom, Tau Why isn't there any more? Or is there a 4th but we can't create the conditions needed to observe them?

[@dexagalapagos]

The fact that this channel doesn't yet have millions of subscribers is criminal.

[@schmetterling4477]

Who are you going to send to jail? :-)

[@luke2642]

Thanks Sabine, I asked for exactly this video in a comment and here it is! 😀😀😀

[@solsystem1342]

Glad to see an explanation of this finnally

[@MrRyanroberson1]

kudos for regularly mentioning the "useless" side of the bad theories, it's so common for people to just flat out say "it's wrong because X" and leave it at that, conversation dead, but you often add why it still wouldn't mean anything even if it were true

[@shutupimlearning]

I cant believe this content is free. Absolutely love these videos!

[@michaelcornish2299]

I was wondering if you could do or have done a video on exactly what information in physics is. Many sources seem unclear about this. You are very good at explaining things clearly.

[@patricktinkham]

Thank you for your excellent videos! If you haven't already, could you make one that illustrates electron capture decay?

[@andyspillum3588]

As I am older than I like to accept I found that "more wrinkles" line a rather bitter pill. However the video was entertaining, insightful, and thought provoking (I love having more questions at the end of a video than I came in with) as ever thank you.

[@gijbuis]

"If that thing you call xxx isn't observable, then it doesn't explain anything... " Right on, Sabine!

[@Rudxain]

I found this video when searching for *photon decay.* Photons must meet 2 requirements to decay: more energy and less relativistic-speed. Interestingly, both requirements are met by simply having mass (yes, photons seem to be capable of having mass!). Having mass is the minimum requirement to not reach speed c, so it "unfreezes" the photon from our frame-of-reference, allowing it to "die of old age"

[@ScottLahteine]

TBF to some schools of thought including Panpsychism, consciousness is proposed to exist as a latent phenomenon that emerges in the inter-relationships between particles and as a consequence of their interactions, not necessarily as a quality of the individual particle. The apparent parallelism and simultaneity of conscious experience (evidenced e.g. by the "distributed experience" of the visual field) is proposed to arise in some manner from entanglement and to rely on nonlocality. That should be testable, and indeed we do find that hard-wiring is required for our conscious subsystems to properly communicate. Of course, the ultimate problem with panpsychism is that it proposes a higher-order or universal consciousness, which can be rejected as unnecessary once you discount telepathy and other unproven parapsychological pleadings. The emergence of consciousness remains mysterious, but we are beginning to make more sense of it, and while we will surely be surprised at many turns I'm confident that panpsychism will never be required to explain it.

[@spanishgame]

I have a question: If you count all the gluons separately, does it not also make sense to count the different color charges of quarks as well?

[@SabineHossenfelder]

Well, yes, not sure why you think they don't count?

[@spanishgame]

@@SabineHossenfelder no, I do think they count, I only noticed that you chose not to show them here, presumably for the sake of brevity, that is all