How Electron Spin Makes Matter Possible

[@Morilore]

Matt: "don't worry, it's just addition and subtraction" Also Matt: *literally derives Slater determinants on-screen*

[@EduardoLauandeTeixeiradeSouza]

You are damn right. I suffered to study this at Chemistry course. And you put this very interestingly

[@kennarajora6532]

ironically, did it in a way that I actually understood it this time.

[@juandavidgilwiedman3490]

@@kennarajora6532 Well, Matt is a great storyteller, this is in part what makes a great teacher.

[@Mp57navy]

@@juandavidgilwiedman3490 If my physics or math teachers would have been 1% as enthusiastic about their job as Matt is...

[@Mastakilla91]

This just goes to prove that it's not math being to complicated to learn but our applied learning methods not being compatible with our brains method of learning.

[@nickpiovesan4361]

"Of course before you want to watch this you should familiarize yourself with the subjects we touched upon in the previous 30 episodes of Space Time..." Love this channel.

[@ManyHeavens42]

Excuse me what did you say I was eating Hahaha

[@robertahrens5906]

I'd be getting smarter if I just had any notion of wtf he just said

[@Kawalajin]

PBS hustle game is wild.

[@flirtwithdanger_les]

I didn't understand this at all - maybe I should watch those 30 vids

[@bardsamok9221]

​@@flirtwithdanger_lesDo it, Ming!

[@Elzilcho87]

This makes me feel like I've accidentally sat in on the wrong lecture, but I'm now too interested to leave. Thanks for the mental stimulation.

[@ScumfuckMcDoucheface]

right? that's a really great description man... way over my head but incredibly interesting and stimulating. =)

[@dialect64]

That was a hobby of mine for a while actually, lol! I would go to my GF's college (which had a more in depth psychology and social science curriculum than mine) and go to all the open access lectures on the topic (was my minor, top of my class, but was focused on audio engineering)! Haha, even ended up in discussions with the speakers more than the students, since half them took it as an elective!😂

[@nathanpeterson1783]

We've all wandered in and then just kept coming back!

[@spracketskooch]

I'm tired, and I read "mental stimulation" as "menstrual stimulation". I'll be on my way now.

[@thetalantonx]

@@ScumfuckMcDoucheface @Jetpack Rorschach... I can't get over your amazing names. :D Thanks for the minstrel simulation.

[@shashikantrivankar3551]

Most textbooks or online lectures gloss over the deep meaning of the spin leaving one unsatisfied with the description. This is the first time i have seen someone explain the concept in a way makes it more satisfying an explanation. Kudos to Dr Matt O'Dowd for possessing such an ability!

[@ManyHeavens42]

Indubitably hahaha

[@ManyHeavens42]

Like I Like Smart people or Something Hahaha

[@SolidSiren]

Well lecturers dont typically have computer graphics. that is where at least half of the understanding on YT physics channels comes from, Id argue

[@ManyHeavens42]

@@SolidSiren yes they do what planet are you living on

[@SolidSiren]

@@ManyHeavens42 no, lecturers do not typically use the graphics used in a channel like this.

[@w6wdh]

Great explanation! Richard Feynman said that if he really understood some aspect of physics, he could explain it to a freshman. But the Spin Statistics Theorem stumped him. He was unable to come up with a simple explanation, which you have done. Bravo!

[@erawanpencil]

This stuff really only makes sense if you throw out any conception whatsoever that 'electrons' 'photons' 'fermions, bosons, etc' are entities doing stuff lol. They're not really particles, they're apparently mathematical square roots temporarily hidden in the complex plane, sometimes not, and everything and some things are connected by 720 degrees or whatever. If you square them, you're rewarded with the knowledge of the probability that they 'might' have a physical property haha. It's cool that something so mathematical turns into semi-coherent physical observations, but it all feels a little disingenuous to represent all this as physics and not a Frankenstein math-physics demon child.

[@psychopompous489]

@@erawanpencil I might be dumb, but isn't that all of physics? You make a series of mathematical models that attempt to describe reality, derive implications, and then use experiments to see which implications are most aligned with reality. It just so happens that in this case the experiment is "can electrons of low spin energy dogpile an atom" to which the answer is no. Also they're not really particles; they're waves most of the time (described by mathematical square roots temporarily hidden in the [...]), and only really become particles for collisions. The idea that their wave functions cancel each other out is a real threat, and seeing as how that would constitute a loss of energy in the universe, violating conservation of energy, the aversion is fairly understandable.

[@williamlavallee8916]

No that's what theoretic physics has hoisted onto real deterministic-observational-philosophical Physics. No theory should be publishable without an experimental test along with it (ala String Theory, etc, etc, etc). @@psychopompous489

[@Christopher._M]

I wouldn't go that far. Im pretty sure most people who understood have a baseline knowledge that goes beyond that of a freshman.

[@Baconlessness]

I've been confused for years about what "half integer spin" meant, and here Matt clarifies it in a few words.

[@Robert_McGarry_Poems]

The Mobius belt, to the rescue!

[@camerondale6529]

Why educators are invaluable to society.

[@voidisyinyangvoidisyinyang885]

Has he done a vid on the Stern-Gerlach experiment? that's an even better explanation but this vid compliements that experiment also. The point being that the 1/2 spin is also nonlocal as noncommutative phase (i.e. asymmetric)

[@LetoJaxa]

Some people will just regurgitate what they've learned. A particle has half integer spin because it is what it is. While those that truly understand it, will be able to logically step through the reasoning and come up with analogies for regular people to understand. In other words, it's not magic and here's why.

[@nickhowatson4745]

@@LetoJaxa it is what is is due to an observer bias. life will always find itself in a universe whose properties and values can support it which gives the illusion of Fine Tuning.

[@Erik-pu4mj]

It took some years to get on my feet, but I started learning about wavefunctions formally this week. Thank you, PBS Space Time, for being my informal learning--up until now and inevitably moving forward. The heuristic understanding of a broad range of physics topics you've given me has done more than aid my education; you've fostered and kept alive an interest I hope to take to graduate school research and beyond. PBS Space Time is science communication at its finest.

[@renderproductions1032]

You should try Issac Arthur as well!

[@max-fj7np]

Best of luck to you! Not exactly the easiest field of study to get into but Im sure you got some rock solid foundations built from this channel!

[@paulmichaelfreedman8334]

@@renderproductions1032 Smart as he may be, I would strongly suggest to him to hire a narrator. No offense to him, but his speech impediment makes it fairly difficult for me to understand. And thus I don't watch his videos.

[@paulmichaelfreedman8334]

@@hyperduality2838 + - , yin yang, positive negative, and so on, and so forth...

[@paulmichaelfreedman8334]

@@hyperduality2838 How about this one: Our universe is dual to the other one in which all antimatter went...solves multiple problems with current theories. Oh and a moebius strip cut in half gives two rings that are interlocked.

[@TimRrstrm]

Does any of this explain why USB plugs need to be turned 540° to return to the correct orientation?

[@mrsmiastef]

Hahahaha!!

[@samsungtelevision695]

If you don’t write this paper I will. It’s precisely the phenomenon

[@pbsspacetime]

Yes. It's well known in physics that USB plugs have 3/4ths Spin.

[@renerpho]

This has to be the final comment in the next comment response video.

[@eloniusz]

Does this mean USB type C is made of gravitons?

[@timwatz2330]

I find it fascinating, how you can break extremely complicated topics down so far, that most highschool grads can understand them. Thank you so much, because nobody taught me this, even in college.

[@everythingisalllies2141]

except that all the fancy talk about electrons, fermions quarks, anything smaller than an atom, is pure guesswork, speculation, as none of those things can be demonstrated to exist in any experiment. They are all imaginary, based on assumptions. We can't even fully explain how electricity or light works without diving into the land of pure speculation. The real process may be totally different.

[@timwatz2330]

@@everythingisalllies2141 What kind of answer is that, so anyway I like Thorium too.

[@everythingisalllies2141]

It wasn't an answer, it was a statement of fact. Modern Physics is full of wild goose chases, deceptions and false assumptions and crap theories.

[@fruity4820]

​@@everythingisalllies2141 "no model in physics is accurate, some of them are useful"

[@everythingisalllies2141]

@@fruity4820 its the ones that are downright purposefully deceptive and wrong that I have issue with.

[@johnedwards2119]

Notice that around the ten minute mark Matt begins to pronounce "square" like an American, that is, with an R at the end, and, only moments later, he pronounces the same word as a Brit, so we are seeing a superposition of pronunciation states transitioning from the ground state, Brit, to the excited state, 'Mercan and yet in this case both states are clearly distinguishable.

[@magisimon4873]

Hahaha

[@ichigo_nyanko]

where is he from?

[@-_James_-]

@@ichigo_nyanko He's Australian.

[@SolidSiren]

Thats called rhotic vs nonrhotic.

[@raleighwalter4250]

Yes, he’s definitely Antipodean and most certainly not British

[@SolaceEasy]

In this video series there is a direct relationship between the incomprehensibility of a topic and the amount of gesticulation that Matt does.

[@Robert_McGarry_Poems]

Abstract concepts deserve a proportional amount of gesticulating for the level of abstractness that they portray. Incomprehensibly is relative to the amount of gesticulating that seems misplaced. It's a function.

[@ScumfuckMcDoucheface]

gesticulation - easily one of the best words ever created, of all time, in any language. =)

[@SolaceEasy]

@@ScumfuckMcDoucheface Luv me 'dem words

[@SolaceEasy]

@@Robert_McGarry_Poems I posit relationship; you state direct function. Who has overstated?

[@SolaceEasy]

🤞 I can safely say 👍 Matt's presentation style is 👏 hands down 👊 effective. 👌

[@karozans]

"If you don't spin, you don't matter." --Aggressive Electron

[@arthurharris9428]

Hahahahaha all spins matter 😛

[@mugwump7049]

Boson Lives Matter

[@Arashmickey]

We can spin if we want to We can leave your friends behind 'Cause your friends don't spin And if they don't spin Well, they're no fermions of mine

[@TheMixxon2]

xdddddddddDDDDDDDDD alfons por favor xdddddddddd

[@justsomedude7800]

😂

[@Jadder88z]

I've never studied quantum physics, and only briefly covered the standard model for A-levels in 2007. I understood almost everything in this video on first pass; that's the sign of a really great teacher. Your ability to explain these principles so simply is testament to your understanding. Thank you for sharing your knowledge and making understanding the quantum world so accessible.

[@bhaskararaogondela3805]

Does electron really spins like this 🤔 can you explain that

[@jojausa4399]

@@bhaskararaogondela3805 no they dont, the cake is a lie

[@StefSubZero270]

Wait you never studied introductive quantum mechanics but covered an introduction to the Stanard Model? How is this even possible wtf

[@crowlsyong]

It's inspiring and beautiful, the universe and your descriptions of it. Thank you so much Matt, the animators, and the PBS team that brings this to us for free. Thank you.

[@parthbartakke7988]

So true❤

[@pdelong42]

Thanks for the belt analogy, I never knew about that! I've long tried to find a good way to explain SU(2) symmetry to people (where "people" includes myself) in an intuitive way. This example is a good one to add to my bag of tricks.

[@soasertsus]

Wait this actually makes sense, I think I finally get now why they have half spins and why the Pauli exclusion principle is even a thing. This is the only channel that helps me understand the why of all the weird quantum phenomena without dumbing it down so much that it ends up just being "they just can't have the same quantum state, it's a fundamental law trust me."

[@ExpensiveGun]

@@hyperduality2838 Damn bro, skip your meds?

[@AboveEmAllProduction]

Haha yes the pauli exception. Indeed. Mathematics.

[@ManyHeavens42]

That's not the half of it the smaller you get you get to unravel everything, and Rebuild Don't tell them .

[@itsiwhatitsi]

@@hyperduality2838 matter and energy, body and soul

[@tetronym4549]

@@hyperduality2838 Disregarding most of the actual content of your comment, I wouldn't use the word "duality" like that, in a video about quantum physics. In physics, the word "duality" has a specific meaning -- Particles are not "dual" to antiparticles, because that implies opposites. In physics, "duality" means that they are ways of describing the SAME thing, with particles being "dual" to waves. There is only one thing between the two of them, particles and waves being the same thing. Some of your dualities you listed, however, are correct using the physics term, such as "Space is dual to time". Albert Einstein's theory of relativity is all about space and time being the same thing, "spacetime".

[@EternalBooda]

Matt almost showed us the mystery of his intrinsic mass.

[@_redmenace1917]

LMAO

[@GearForTheYear]

wtf?

[@scottief8616]

Jail!

[@Garresh1]

*bonk*

[@user-wo5dm8ci1g]

PBS Space Time doing humor about privates was a fun new thing for me too.

[@runonwards9290]

Love this, the Pauli exclusion principle is assumed to be fundamental. I'd love to see more vids about the most fundamental principles

[@HermanVonPetri]

I'd like more explanation as to why the assumption is made that two electrons would resist entering the same state rather than simply annihilating each other as the math would seem to suggest. I know that that this is demonstrated experimentally, but how does the math indicate a preference for one outcome rather than the other?

[@nickhowatson4745]

@@HermanVonPetri particles with 1/2 integer spin cannot occupy the same state. its the Pauli Exclusion Principle.

[@ScumfuckMcDoucheface]

@@nickhowatson4745 YOU'RE the pauli exclusion principle!!! =|

[@spudmcdougal369]

I asked the same thing over on science asylum.

[@nickhowatson4745]

@@ScumfuckMcDoucheface its just the way it is. we just happen to be in a universe where these values and property's allow for life. so of course the values are what they are its an observer bias.

[@kaiezon5655]

“…and there would be no such thing as chemistry..” Go on. I’m listening

[@MargoMB19]

I love the intros on Space Time videos, they are always perfecting intriguing and kind of quirky.

[@dominikbeitat4450]

Next episode: Matt explains electron spin again, but this time with jumper cables, because you didn't pay attention.

[@Fres-no]

JUMPER CABLES...... BWAAAAAAAA!

[@nickllama5296]

I did pay attention, but the entry fee was attention x 1.5

[@arthurharris9428]

Hahahahaha

[@SoleaGalilei]

I understood that reference!

[@valjean76]

this channel is getting weird now.

[@pecan4434]

This one's really well written even for the already high quality level of this show. It could've easily been incomprehensible but it was somehow really clear.

[@mikotagayuna8494]

This man just risked getting his pants down for us to understand all these complicated concepts.That is commitment, folks.

[@magisimon4873]

LoL

[@AboveEmAllProduction]

My pant are down do you want ip adress for webcam

[@burpie3258]

Reminds me of that one Nathan For You bit...

[@jamesdyer5335]

In my head this Dude was already, "The Hot Physicist," this joke almost sent me to horny jail.

[@antoniomaglione4101]

Compliments for the clarity and precision of your explanation of Fermions and Boson, and the Pauli principle. Thank youi...

[@benr3799]

2:55 I was gonna guess boomerang tbh, I was so prepared for Matt to just surreptitiously slide one out of the front of his zipper, I know you lads stay strapped at all times over in Australia 🙌

[@johntavarez6605]

I honestly can't express how happy I am that I found this channel who knows how long ago Thank y'all for all the great educational content!

[@jamescollins4500]

"nonoverlapability", I'm never going to forget that word.

[@3hallaman]

i feel like where I live, unoverlapableness would be more linguistically productive

[@0xf7c8]

@@3hallaman 'Unoverlapableness'. Now, that's a nice word.

[@alistairlacaille]

I'm gonna need some hyphens in here please. The amount of extra brain power needed to parse these 'words' without them is asking too much.

[@alistairlacaille]

@Ranjit Tyagi ?

[@alistairlacaille]

@@innerfield5481 Waves interfere and overlap, not particles. Part of the weirdness of particle/wave duality.

[@EebstertheGreat]

I still remember a math lesson in middle school covering the precise mathematical meanings of common words like sum, product, factor, by, term, less, more, at least, at most, etc. In one of the problems assigned for homework, it asked us what was wrong with a store advertising a sale as "all items up to 20% off or more!"

[@Robert_McGarry_Poems]

No commas. Shame... Could have saved grandma too. Let's eat grandma!

[@alwaysdisputin9930]

Such a store should speak with better error bars in the future.

[@pierreabbat6157]

Another phrase that irks me is "one of the only" followed by a plural noun and no number. If you don't know the number, say "one of the few".

[@doctorkropotkin6710]

I remember an advert for a chocolate bar that claimed it was "up to 80% fat free". Sounds good 'til you think it through.

[@kashu7691]

@@doctorkropotkin6710 a chocolate bar of 80% pure fat is a terrifying thought

[@MegaBrokenstar]

It takes someone like you, equally obsessed with astrophysics (and therefore GR) and quantum mechanics to become the sort of master-of-all physicist and communicator that you are. I consider you to be one of the leading overall scientists of our time.

[@LMProduction]

I love that you guys always happen to make content that relates directly to the courses I’m doing. Good timing

[@terryboyer1342]

Matt: There's a chance this episode may get a little weird. Me: I couldn't possibly get any more confused than I already am.

[@greenshadow622]

Matt: Hold my beer.

[@LKRaider]

Me: I was worng D:

[@Haannibal777]

I agree. I did not expect him to take off his belt! I would advise not to get even weirder. Certain things are better left to the imagination.

[@DolphinSMG]

Right? 😂 It was as if I was listening to someone speak a foreign language and they stopped for a moment to tell me, in english, that I wouldn't understand the next part

[@AlephOneHalf]

Matt: Hold my spinor.

[@4fmagnet]

Woah, there! You have said/depicted something at 13:04 that could be very misleading without proper explanation! You have depicted the states as 'ground' and 'excited', implying these are energy states. Good so far. You have depicted the electrons as blobs with no assigned spin, and I understand this was done to get your point across. BUT, the electrons do have some intrinsic spin (+1/2 or -1/2; alpha or beta, however you want to call it--in the lab frame with respect to some axis that would align or anti-align with a magnetic field). What you have described (or implied) is the triplet state (both electrons are "spin up"--parallel), in which the "spin" portion is the wave function is symmetric and the "spatial" portion of the wavefunction is antisymmetric (for a total antisymmetric wavefunction). In this case, everything you said is correct. However, especially important in chemistry, is the single state (one electron spin up, the other spin down--antiparallel), in which the spin component of the wavefunction is antisymmetric and the spatial component symmetric. In this case, two electrons CAN both be in the ground energy state, as long as they have opposite spins. Of course this is a distinct quantum state, as you said, but not a distinct energy state. I just don't want anyone to be confused or walk away with the wrong impression.

[@davidhand9721]

You're right; that raised an eyebrow for me, too. Without that context, his explanation doesn't really have a link between spin and the exclusion principle at all. It sort of describes spin in the usual Copenhagen way, then separately describes anti-symmetric wavefunctions, but with some really weird simplifications. _f_ and _g_ are normally two wavefunctions, psi1 and psi2, not usually two different energy levels. Then there's _A_ and _B_ which are usually two positions, and that's even more confusing because it makes it look like we are talking about swapping particle identities or energy levels, not positions. The important bit, of course, is to show that the two wavefunctions can't be the same if they have the same state, and Matt gets there, but the extra bits about multiple energy levels and ambiguity about what kind of parameters are going into the combined wavefunction are just distracting from the point that opposite spin is what makes the particles pair up in the same state. And then he doesn't really explain how the effect is related to contact forces at all, he just states that they are one and the same. Overall, not the best episode of... SpaceTime. Unrelated note: go read the first two papers you find when you Google "Ohanian Dirac field". I can't recommend them enough for understanding spin without all the belts and ribbons and teacups and general insanity surrounding spin. They really are spinning after all, just on the outside, with charge density flowing twice as fast as mass/energy/probability density, no superluminal flow required. Much, much easier to wrap your head around, though I don't know how exactly that fits in the spin statistics theorem.

[@michaelcollier5219]

@@davidhand9721 I agree that Matt should have done better at explaining how the Pauli exclusion principle connects to solids and molecules and chemistry, but he still explained the details of the principle better than did all the quantum professors and textbooks I ever had. Had he spent just 1 minute more on that part of the explanation, he would have nailed the topic 100% perfectly. And I strongly disagree with you that "all the belts and ribbons and teacups" were unnecessary for understanding spin; those visual analogies were immensely helpful for my understanding, and I'm grateful that he used them.

[@CATinBOOTS81]

Well... you're right.

[@tantamounted]

Thank you. This, combined with the video above, just explained a bit more about electron shells around atoms, and why they layer the way they do.

[@davidhand9721]

@@michaelcollier5219 The reason you needed those visual analogies is that you have not yet read that paper by Ohanian, titled "What is spin?". The Dirac field really is spinning, or more accurately flowing circularly. Spin is spin. The visual analogy you need is... a thing spinning.

[@bomb_and_gouge]

The best thing I know is when I open my laptop and see PBS Space Time posted a video 5min ago! Thank you!

[@curiodyssey3867]

Phrasing

[@benr3799]

14:40 man it was just yesterday I was watching Cyberchase on PBS on my cathode ray tube tv. Now I have Matt dropping trou’ while explaining spinnors. Thank you PBS. And to viewers like you, thank you.

[@stringjazz2937]

Never before have I ever heard a most clear and beautiful Electron Spin before. Thank you very much.

[@mandelbraught2728]

This one totally rocked my world. I freaking love this channel! Thank you. I'm so appreciative that you don't treat us normal schlumps out here like idiots. You really make an effort to explain the principles. It's great. Please don't stop. Dr. Matt, does that mean your belt has integer spin? Are those cg pants?

[@renerpho]

What gives Matt mass is the same thing as what holds up his pants. Now that's some hypothesis there.

[@theopantamis9184]

The missing piece I was searching for so long was an intuition of why spin rotation properties imply particules swaping introduces a minus sign. I have it now, I can die in peace x)

[@Tinker1950]

Try again - that word salad was meaningless

[@Robert_McGarry_Poems]

Right... Mobius strips are even cooler now!

[@Robert_McGarry_Poems]

@@Tinker1950 Except the part where he used spin 1/2 meaning. It totally works out.

[@theopantamis9184]

@@Tinker1950 You know what you could do ? Asking question if you don't understand or helping instead of being mean :) You should try it, it makes you look less ugly actually !

[@Tinker1950]

@@theopantamis9184 It's still meaningless. Even after pointing it out, all you do is whinge like a 10 year old instead of looking at your comment and re-writing it.

[@lordofchaosinc.261]

The moment I read the title I knew that's an episode I wouldn't fully comprehend.

[@beepboop204]

for me, it is retaining it after i understand what he is saying. maybe that has to do with this potent cannabis im smoking.....

[@TheoEvian]

The Parth guy does this same explanation and also Eugene Khutoryansky and his explanation I like the most, since it has pictures. The idea is always the same - if electrons are indistinguishable it means they can't be in the same place because their wave functions would interfere in a bad way.

[@wleizero]

I wish this video had been available when I was at Uni. Spin was the stumbling block and made me stop trying to understand, and just "shut up and calculate". Really awesome video!!!

[@1.4142]

Wow, you've really got this stuff under your belt!

[@ryansears4387]

This makes more sense than my quantum mechanics lectures in college lol I still did well in the class, but didn't really understand where the math came from.

[@TheGanamaster]

I guess this is where the "meth" jokes had started.

[@DrWhom]

you still don't

[@Joso997]

Honestly I love this show and this guy.

[@samsungtelevision695]

Amen. Gives me good memories of college back in the 00s

[@MasonDixonLine1]

And just like that, after a year of trying to figure out what spin 1/2 actually means, he explains it so clearly.

[@rainmanj9978]

Right but since they don't spin it still doesn't make sense physically. The waves make sense but how do they create waves? 360 degrees is back to zero but the wave is traveling up stroke 720 degrees is back to where you started started on a wave but yeah still not sure.

[@tnb178]

This guy never stops looking into the camera while doing the whole belt trick. Real pro KZbinr.

[@samiaario8291]

This channel is excellent at bridging the gap between pop science and a deeper understanding of physics, and this particular episode is a shining example of that.

[@tzaidi2349]

I think I speak for my fellow Spacetimers when I say that I love that I have to watch it a few times to get it. Always pushing the limit of my understanding. I also think were all looking forward to future explainations where Matt takes off his shirt to explain entanglement. #physicsbod

[@ChrisWalshZX]

"... for you, here, on spacetime" - that's a bit of a cop out! It's a reference to the channel, not to spacetime itself! Excellent video. Absolutely amazing explanation of half-spin fermions and why the obey Pauli. Thanks.

[@hellboy1488]

Teacher: Tell me you're into physics without telling me you're into physics. Me: *Takes off belt*

[@AshenZu]

There just aren't the correct words for how much I love these episodes. Particularly in one like this where I have a eureka moment. As opposed to the point running away like a child on sugar playing hide and seek.

[@СергейБыков-ж1в]

Thank you for going deeper and explaining the Pauli exclusion principle. Was very interesting to watch.

[@ChrisBrown-pw2lb]

I've never watched one of the vids without hitting the like icon. I don't understand all the math but I still know enough to enjoy these vids. Thank You Guys.

[@Roystonsmum101]

Does…… does Matt call his dong ‘Mysteries’? Another great episode that I think I understood a tiny bit more than half of, keep them coming!

[@ChemEDan]

The mystery machine

[@dionh70]

"Mystery", singular

[@umber6937]

Hmm, the implications of that may be worrying

[@paulmichaelfreedman8334]

Well i surprised myself by predicting the superposition as soon as Matt was talking about psi and psi squared, and that psi itself cannot be directly measured - it has to be squared first to remove any negatives (distribution probability cannot be negative). By taking the square root of psi squared there are two possible answers - a positive and a negative one, but which is which? -> superposition.

[@inkasaraswati7625]

@@paulmichaelfreedman8334 Oooh I didn't get the connection to superposition. I was too busy thinking that even though math was never intended to describe these things (it was probably first invented to count apples or something), millenias and a multitude of complexities later, it still is able to describe our physical world perfectly.

[@AlienScientist]

This gives me great hopes for our upcoming Alzofon experiments...

[@cowlinator]

What is this?

[@MrRoguetech]

@@cowlinator Anti-gravity idea that Alzofon's own experiments proved wrong 30 years ago.

[@MrRoguetech]

@Science Revolution You seriously don't understand how tides work??

[@sleeplessforawhile]

That 720 "rotation" makes me think on additional dimensions... Seems like the electrons and fermions in general, has to complete a "trip" on those additional dimensions to reach what we see as a complete simetric "trip" before it returns to original state. Thanks Matt. Your videos are a beautiful gift for me.

[@cantubloodaxe768]

I kind of forgot what we were trying to prove till you reminded me at the end. It all makes sense now!

[@Sam_on_YouTube]

I used the Pauli Exclusion Principle in my metaphysics papers back in college. I used it to disprove the concept of "identical but numerically distinct." If two things are truly completely identical, then they cannot be well described with any distinction, they are inherently too entangled to make such a distinction. That causes many confusing problems in the philosophy of material composition (also called "mereology") to simply resolve themselves.

[@jrobinson1215]

Chairs, chairs everywhere!

[@anywallsocket]

it's really pretty obvious in retrospect: if two things are identical, who's to say they aren't actually one thing? i believe the pauli exclusion principle falls out of the conservation of information, not the other way around.

[@Sam_on_YouTube]

@@jrobinson1215 A typical setup for a philosophy thought experiment here would be "suppose you are cloned so there is an identical copy of yourself, but in a different place." To which I reply "that violates the laws of physics." Now that isn't ALWAYS a problem, but in many of these cases, the way it violates the laws of physics simply destroys the whole motivation for the question and leads to an obvious answer.

[@Sam_on_YouTube]

@@anywallsocket If I remember correctly (which I might not) that's how I learned it in Quantum I.

[@Jason-ip6li]

I feel like "literally just addition and subtraction" means something different to Matt than it does to me...

[@originalph00tbag]

Exponentiation is just a *lot* of adding.

[@Jason-ip6li]

@@originalph00tbag This information is as technically true as it is unhelpful.

[@princeofcupspoc9073]

Algebra would have been more accurate.

[@SolidSiren]

Oh come on. The symbols dont matter, dont let them intimidate you. Im sure you understand that 1 plus negative 1 is zero and so forth. and algebra.

[@debyton]

The trouble with reverse engineering from a fixed perspective in nature, as we are often forced to do, even with accurate data, is we are forced to draw conclusions that fit the data, and yet, those conclusions are not guaranteed nor even likely to land anywhere near the true description of reality. For example, the earth-centric universe. The correctly observed, and measured motions of the planets didn't reveal in an obvious manner the underlying flawed perspective. Flawed descriptions and supporting mathematics and postulates can provide frequently accurate results even to 10 decimal places because they describe the symptoms and not the cause. One can measure and describe everything about a cool breeze as it passes over you and yet reveal nothing about whether it is the last gasp of a distant dying hurricane, or from a nearby wind turbine, or is a direct well-traveled atmospheric perturbation of our parent sun's energy. Absent the correct description of the underlying structure of any natural implementation, refinements to observed phenomena and their representative mathematics and symbology will continue to be flawed. Upon the realization of the actual defining structure, all of the previous notions are often deprecated for a new description.

[@TheRealInscrutable]

I'm looking forward to when we can make stellar observations "simultaneously" from many tens of light years apart. The debate over the non-privileged position from which we now view the universe can be settled. Sadly it'd be much more fun if it turned out we had a privileged position. Oh well.

[@harbingerdawn]

"The correctly observed, and measured motions of the planets didn't reveal in an obvious manner the underlying flawed perspective." On the contrary, it was precise and accurate measurements of the motions of the planets that allowed Kepler to discover the elliptical shape of planetary orbits, and thus construct a simple and elegant heliocentric description of the solar system that matched observed reality far more closely than the more complex geocentric model accepted at the time. The point you're making is a valid one though.

[@chewyjello1]

Considering that the literal only thing we can ever have direct access to is just patterns caused by the electrical impulses of neurons...I'd say we are doing pretty well. A direct, intuitive understanding of reality is probably too big an ask. But we can continue to refine the tools that allow us to play with reality (if there is such a thing as a single objective reality) even while trapped within our dark, windowless skulls.

[@MylesKillis]

@@chewyjello1 perception eats rationality for breakfast

[@SolidSiren]

I used to say things like this. Then i learned enough to strt really learning physics and chemistry and now i have an inkling of an understanding as to just how impressive our theories really are, internal bias and all...

[@toughenupfluffy7294]

Well at least now I know all about the Pauli Exclusion Principle, and all that jazz. I can go to that physics department meet and greet now, with full confidence. Thanks, PBS Spacetime.

[@davidcarroll2911]

All of these space times are great, but this one was a cut above. Very nice job!

[@camerondale6529]

I think a lot of confusion around spin is the fact that people think it has to do with the physical property itself, when in reality spin describes a mathematical property which relates to the behavior of particles within a particular frame. Think of it as spin = math of particle, not movement of particle.

[@tim40gabby25]

Spot on.

[@davidhand9721]

Read Ohanian's paper titled "What is spin?". You're welcome.

[@davidhand9721]

@@hyperduality2838 define "dual to" before you copy-pasta this again.

[@davidhand9721]

@@hyperduality2838 can you explain how duality makes any testable predictions?

[@davidhand9721]

@@hyperduality2838 sorry man, this sounds like a lot of confetti and no tool to me.

[@googoogjoobgoogoogjoob]

It's weird, but not as weird as his trousers not falling down.

[@Sam_on_YouTube]

I studied philosophy of physics because once I got past sophmore year, the math required for a physics major just got hopelessly out of reach for me. But I still really wanted to learn the concepts in Quantum II to apply to my philosophy. I convinced the professor to let me audit the class, pass/fail and instead of the final, to write a philosophy paper about the subject matter. I explored whether a helium nucleus was one boson or four fermions. Ultimately, I concluded that the correct answer depends on the perspective set based on the context of the question. If you are exploring the macroscopic behavior of liquid helium, it is a boson. Explaining it as 4 fermions is simply not a useful answer to the question being asked. It is an answer to a different, more fundamental question and therefore, simply the incorrect response.

[@tomf3150]

Congrats, you have reached metaphysic. Litterally.

[@jimgraham6722]

Good

[@kenlogsdon7095]

@Sam Sorry but you've lost me. How does the quantum status of the helium nucleus affect the behavior of helium atoms in their liquid form?

[@shazide5358]

The helium nucleus is a boson formed by 4 fermions. I don't see whats the problem with this answer.

[@kenlogsdon7095]

@@shazide5358 The problem is that the nucleus of an atom doesn't directly interact with the nuclei of all the other atoms around it, it's the electron shells that do. Or am I somehow mistaken on that point?

[@sheepwshotguns42]

pretty sure ive seen about 80% of all of pbs space times videos, and this remains the best one to this day!

[@KellersTechCorner]

@Steve Bogucki, I agree, PBS SpaceTime has been my godsend. It has opened my eyes so far beyond what I thought was a love for astrophysics.

[@wayneyadams]

This is why the periodic table looks like it does. Each electron in an atom is assigned a set of four quantum numbers. One is the energy level, two are moments (angular and magnetic), and the third is spin. The spin can either be +1/2 or -1/2. The levels, or shells as they are called, are numbered much like the floors in a building. The levels can be divided into sublevels. The number of sublevels correspond to the number of the shell. The first shell has one, or effectively no sublevels. The second has two, the third has three and so on. These sublevels are further divided by a magnetic component into what we call orbitals. This was probably a bad choice of words because it misleads people into thinking that the electrons orbit like planets around the Sun. Each of the orbitals is formed by a maximum of two electrons, one with +1/2 spin and the other with -1/2 spin. Notice I said formed and not filled. Orbitals are not little empty containers waiting to be filled, they are formed by the electron, i.e., no electron, no orbital. More accurately, they are the volumes of space where the probability of finding the electrons are very high. The first energy level has one orbital and thus holds two electrons of opposite spin. It is a spherical orbital which we call s. The second energy level has two sublevels, with an s orbital in the lower energy sublevel, and three orbitals, each holding two electrons in the higher energy sublevel. We call these orbitals p. So this level can have 8 electrons, 2 in the s orbital, and 6 in the p orbitals. The third level gets more complicated. It has the two s orbitals, three p orbitals and an additional five orbitals, each holding two electrons, we call it d. So this energy level can hold 2 + 6 + 10 = 18 electrons The next energy level has an additional 7 orbitals called f, holding two electrons each for a total of 14. Find a picture of the Periodic Table and notice how it is arranged. The first row is the first energy level, the second is the second and so on. On the left are two columns corresponding to elements that have their outermost electrons in the s orbitals. The first column has one, the second has two. Over to the right you will see six columns, for elements with their outermost electrons in the p orbitals. Tucked in between a little lower in the table you will see a section with ten columns corresponding to the d orbitals. Finally at the bottom there are two rows of elements of 14 columns corresponding to the f orbitals. The critical point is that each electron is assigned a set of four quantum numbers, and no two electrons can have identical quantum numbers. The result is that each orbital can be occupied (formed) by two electrons of opposite spin, +1/2 and -1/2. -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- This section is for serious chemistry students. The first quantum number is n and it corresponds to the energy level. The second quantum number, the angular moment, is l. It has values from 0 to one less than n. For instance: n = 1, l = 0 n = 2, l = 0, 1 n = 3, l = 0, 1, 2 The third quantum number, the magnetic moment has values from -l to +l, including zero. n = 1, l = 0, m = 0 (the s orbital) n = 2, l = 0, m = 0 (the s orbital) l = +1, m = +1, 0, -1 (the three p orbitals) n = 3, l = 0, m = 0 (the s orbital) l =+1, m = +1, 0, -1 (the three p orbitals) l = +2, m = +2, +1, 0, -1, -2 (the five d orbitals) The fourth quantum number, is s, the electron spin (remember electrons do not actually spin) has values of +1/2 and -1/2. So each of those orbitals could have two electrons of opposite spin. For example two electrons occupying a p orbital in the second energy level might have numbers: n = 2, l = +1, m = 0, s = +1/2 n = 2, l = +1, m = 0, s = -1/2 -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- As Dr. Don Lincoln says at the end of his FermiLab videos, "Physics is everything," to which I am going to add, "we would not be here without Chemistry." Wayne Y. Adams B.S. Chemistry M.S. Physics

[@SolidSiren]

That's not for serious chem students. I took chemistry 1 and it included all of that. Plenty of kids in there were NOT chemistry students, or even science degrees actually for some reason. Im doing biophysics, so I have taken bio, chemistry AND physics every year so far.

[@SolidSiren]

I see you did chemistry and physics. Thats great, Im sure the chemistry helped!

[@wayneyadams]

@@SolidSiren It actually worked the other way. I had planned to do a double major as an undergraduate, but because of some red tape, I had to use all my physics credits to satisfy the university's silly 3rd science requirement. Even so, the physics made the chemistry much more understandable.

[@wayneyadams]

@@SolidSiren I'm talking about the people who watch KZbin videos, not chemistry students.

[@janneaalto3956]

I remember when I realized, as a little kid, how little there is to solid matter. Soon after the realization, I got sick and a high fever. A couple times during that fever I imagined the world as it really is, with solid matter less concrete than mist, and then I'd get horrible vertigo with cold sweats as I grabbed the sides of my bed and imagined the twelve thousand kilometer abyss of super hot intangibility beneath me.

[@DFPercush]

On the bright side, at least you don't have to worry about the sun not rising in the morning like some ancient peoples...

[@Kumquat_Lord]

Any plans to cover the new black hole pressure discovery?

[@ScumfuckMcDoucheface]

kumquat seems like it should be censored with little stars or something in front of children haha what a great, fantastic fruit, as well as great and fantastically dirty sounding name.

[@jonmyles4531]

Nice explaination, we I read Physics BSc at Uni we had lecturers, of which very few had any skills in teaching or communicating with us students; and a library to research plus purchase of set books; no such thing as the internet or KZbin in late 70's. We wrote software on paper and got the punch cards days later - Halcyon days!

[@markdanielpatureau2925]

After watching this episode for the 3rd time, each viewing more interesting than the previous, I am beginning to grasp spinor theory. Thank you for enlightening me Matt!

[@firefly618]

Oh, I see! If their wavefunctions are anti-symmetric, any configurations where two fermions occupy the same state have zero amplitude and therefore zero probability of measurement. Nice.

[@Brandon_Tyr]

Well they would have zero wave function. But instead the Pauli Exclusion Principle swoops in like some magic voodoo and prevents it from happening.

[@alwaysdisputin9930]

@@Brandon_Tyr Why is voodoo necessary? Doesn't the zero probability of measurement mean you can't get ever find 2 electrons crammed on top of each other (i.e. with the same 4 quantum numbers)? I didn't understand the video & I don't know why whatfireflies said if their wavefunction are anti-symmetric then 2 fermions occupying the same state have 0 amplitude

[@alwaysdisputin9930]

@whatfireflies Why do you say: 2 anti-symmetric wavefunctions = 2 fermions occupying the same state have 0 amplitude?

[@enterprisesoftwarearchitect]

BETTER EXPLANATION than the whole video! I hate when they say Pauli Exclusion Principle and then don’t explain it.

[@enterprisesoftwarearchitect]

@@hyperduality2838 watch Alex Flournoy- he’ll set you right about dual vector representations in particle physics my friend. Get it straight- you are almost there.

[@navinsingh1730]

I love how Matt simplified math to feel like a child's play. He can teach a horse to drink water in a glass!

[@richp6716]

Why is the horse in a glass?

[@cam4636]

@@richp6716 He didn't use the anti-symmetric wave function

[@navinsingh1730]

@@richp6716 Due to quantum uncertainty!

[@hektor6766]

@@richp6716 Ba-dam-tsss!

[@Factnomenal]

Another great video from the legend himself! 👏

[@SoulDelSol]

I didnt know he was a legend. He is pretty smart so I'm not surprised

[@vajrapromise8967]

This actually makes sense and doesn't seem too complicated, I wonder why it has been presented before as such a mystery. Must be that many others don't really know what they are describing, this is the best description I've ever come across though and look forward to learning more-Thanks!

[@pretzelboi64]

Some people just like to impress and appear intelligent when explaining things instead of focusing on actually getting the person to understand. It's the biggest driver in the failure to learn things for most people imo

[@klauskervin2586]

This is one of the best episodes of Space Time yet. Thank you for the great content!

[@christopherdurham1999]

Episode might get "quantum-weird"... I mean, isn't that what we're here for?

[@renato360a]

For a laymen like me, the whole argument seems to be based on the fact that "you can't just vanish electrons" (12:55). But I don't know about that.

[@Jerom_]

If both electrons are in the same state, the wave function would be zero. That means that the squared wavefunction, which represents the probability of finding the two particle system in that state, becomes zero. In other words: the chance of both electrons being in the same quantum state is zero. Another way to make that same statement is to say that two electrons cant occupy the same quantum state. Hope that clears things up.

[@ZetaFuzzMachine]

You're right, that phrasing was unfortunate. The thing is that, if two electrons share the same state, then the wavefunction (psi) of the swapped pair would be the same as minus the wavefunction (-psi). And when you have the equation x = - x the answer is x = 0 When psi = 0, it means that there are no electrons there. (Because the wavefunction is a statistical tool that represents probability. When the wavefunction is null, then probability of existence is null)

[@scotthammond3230]

Exactly.. psi = -psi, 0=0.. ok thats bad, you cant disappear electrons! The math works, but it doesnt explain why electrons dont overlap and disintegrate each other.

[@seanathans103]

@@scotthammond3230 lepton number and charge would not be conserved

[@twistedtachyon5877]

@@seanathans103 now we're getting somewhere! Next step on this rabbit hole: particles annihilate each other all the time. Do all such annihilations have balanced charges? All the cases I know of do, now that I think about it. Does that mean that, in a sense, "we can have nice things" because, while electrons would all like to vanish into oblivion, they can't manage it because they all have something about themselves they can't let go of? I guess the overly simplistic explanation about charge holding things apart is better than I thought. (It's optimistic nihilism ark the way down...)

[@FormlessBody]

Bold of you to assume I'm not falling through my chair right now.

[@cwojomusic556]

Will need to listen to this more than once. Ill be back.

[@deeponjitbose8188]

Best explanation of spinors and Spin-statistics Theorem

[@nikanj]

7:55 Matt is tired of being told by the producers that engagement drops when he does maths. "If they don't like it they can go and watch SciShow. This channel is about getting into the weeds."

[@nikanj]

This isn't a dig at SciShow, they make great content and make science more accessible. As does Space Time, they're just catering to different levels of assumed knowledge/accessibility.

[@hektor6766]

@@nikanj I like being assumed as big enough to take it.

[@InfinityOrNone]

Bit late, but "up to 10%, or more" doesn't mean "every possible number." "Up to 10%, or more" can be expressed as being formed from the two sets of, "up to 10%" (a set of all values below 10%, relative to the speed of light in this case), expressed as x(0.1c). If we take this as the sum of both sets, it includes every possible value *except* for that 10% of c. If we take this as a set that contains only the elements present in both sets, then it contains 0 possible values. Either way, we know that 0.1c is off the table.

[@pepe6666]

oop, hes got ya there!

[@chrisfrolik4014]

"We can't observe Psy" *Gangnam Style plays somewhere off in the distance*

[@Epistemonto]

Here I was thinking Hikaru No Go's Sai, but yeah...

[@LuisSierra42]

They are in a state of superposition

[@martinl6133]

No idea if you'll see this, Matt. But something good for you. I'm 67. I was a scientist, but not a physicist. So, I often have no idea what you're talking about, unless I have a "hook". At school (yep - 50 years ago!) I learned, in Chemistry, about the exclusion principle, using the simple "rings around around a proton " diagram. Put energy into an electrons jumps it to a higher state (further out), so the electron there has to move out of that ring. I know this is really, really, simple. I imagine they don't teach it this way now. But it's nice that, from chemistry lessons, 50 years ago, gives me that "hook". Still don't understand half that you say, but I can kind of get it. That's why I subscribe. So, thanks 👍

[@InternetRando42]

His *utterly* deadpan humor, on top of the thoroughly informative summary of much harder math (I took quantum in college and only sorta got it) has made me fall in love. With quantum, thought maybe with the presenter a little bit.

[@Danledz]

"You spin me right round baby right round"- Electrons, maybe

[@vblaas246]

"Molecular Shape of you" - Ed Sheeran parody

[@hektor6766]

"... right round, round--and stop!"

[@baremetaltechtv]

"All electrons are exactly the same. You can swap any two electrons etc..." I think the guy who thought it was turtles all the way down must have made a mistake.

[@Cronos804]

Physics is all that matters but math is all that counts.

[@ConstanceAllard-mw1xs]

LOL!!! Too shay!!

[@SinisterBlackShadow]

Absolutely awesome and clear explanation of the Pauli Exclusion Principle. I took a fair bit of time out of my younger days trying to get a grasp on this, whilst this video would've helped me in minutes. Years later, I have lost some of that knowledge but with the help of this video, I can now also remember in minutes. This video reminds me of another interesting point...I believe particles (bosons or fermions) tend to decay to lower energy (mass)...so it seems we have proof that nothing is less massive than an electron, with the same properties. In other words, it is stable because nothing else exists. Now I could be wrong here so don't take my word for it.

[@SteveFitzpatrick1]

I'm glad that I'm not falling through my chair... Excellent presentation and explanation, distinguishable from other KZbin science shows!

[@LyonsTheMad]

If two fermions occupying the same level is equivalent to cancelling each other out, or vanishing them, as you put it, what exactly is happening when the outward "pressure" of the exclusion principle is overcome, as in a collapsing black-hole-to-be? We know they don't just lose a ton of their mass and charge upon collapsing (or at least this seems absurd to be), so what is going on here?

[@Benus00]

In the case of black holes: we probably don't know, since our current models break down and we need a theory of quantum gravity. Are there any other examples, where the pressure us overcome?

[@TlalocTemporal]

I think if you added enough energy to squish two electrons together, then you'd get that much energy out of the resulting annihilation event, plus the energy of the electrons. Charge and a few other things need to be conserved between the electrons and the new particles, so that limits what can pop out. The most common result is probably two very fast electrons, but muons or taus might happen too. Beyond that, I don't know.

[@srujanbhagwat1293]

This is an incredible question! I hope this gets addressed, maybe in an episode about the source/breakdown/overcoming of degeneracy pressure.

[@gregorykhvatsky7668]

@@Benus00 Neutron stars

[@Benus00]

@@TlalocTemporal The creation of new particles would be described by interactions with other quantum fields. I don't think, that has anything to do with the degeneracy pressure. How would you squeeze the electrons together? In particle colliders, the electrons are moving in different directions, so they are not in the same quantum state. Do any other events of electrons squeezing come to your mind?

[@KoningFelix1]

I remember reading about the bistromathics in Douglas Adams' works and how the mathematicians all started to have conferences in restaurants and observe the weird behaviour of numbers there. It's a typically Adams concept and I liked how he based an entire math concept on mathematicians overeating and getting downright obese figuring all this stuff out. It's just very funny and silly. And then today I learned a famed, real life physicist base his theories of quantum spin on belt trics. Maybe this Adams guy was on to something.

[@tim40gabby25]

Group bills obey the Pauli bistro principle in that no 2 individuals finish up paying the same amount, even if they ate and drank exactly the same.. :)

[@EvenTheDogAgrees]

Man, anyone remember when this channel required nothing but a keen intellect to be able to follow along?

[@Aurinkohirvi]

Nope. I must have found the channel later.

[@BU_IDo]

What fascinates me even more is that a small but significant portion of the human species completely understands the non simplified version of this explanation on matter. Why is it so foreign to the majority of us but so easy to digest for these few.

[@johnclark8359]

I think that just may be the best episode yet. Thanks a lot

[@Rhekon]

I thought I wasn't falling through my chair because I'm fly. That theory is out the window.

[@itsafluke6574]

Fun fact, if you have the power to rearrange electrons, nuetrons and protons at will, you can change a sea into blood...

[@itsafluke6574]

fine tuned Gravity control could achieve this...

[@Kumquat_Lord]

Also a fun fact, protons are sour

[@dissonanceparadiddle]

@@Kumquat_Lord how do they know that? 🤔

[@bowenheinrich]

@@dissonanceparadiddle we detect sourness by the presence of H+ ions in acids (which are just protons)

[@ryanturner6920]

@@dissonanceparadiddle He's a Pro... and eaten Tons.

[@ResandOuies]

Ok, what am I missing here? We can't shove two electrons in the same quantum state because they then would be out of phase, destructively interfere and cancel out and we can't "just vanish electrons". But why can't we just "vanish electrons"? Isn't that pretty much the same that happens when two photons are out of phase and adds up to zero and thus no photon?

[@katzda]

I was going to ask the same question

[@K-A5]

Matt, answer this one please!

[@LaSDetta]

I have the same question. Maybe the answer lies in the dirac equation the he mentioned at the end?

[@frede1905]

I think Matt was a little unclear there. The problem is that a wave functon that's zero everywhere is not normalizable, ie. the probabilities don't add up to one. Essentially you get that the probability to find the two electrons in the same state is zero. Also, note that we're not describing annihilation processes here. We're simply writing down the antisymmetric wave function of the two electrons, and asking what that wave function will be if the two electrons are in the same state. Had we tried to describe some kind of annihilation, then the wave function would undoubtedly have looked very different, and we'd probably need quantum field theory as well. Though in reality, two electrons won't annihilate just because they get close to each other.

[@LaSDetta]

@@frede1905 How does the symmetric wave function look for photons out of phase with each/other and how is that different from electrons in the same state?

[@GerinoMorn]

I like how the famous "single electron traveling back and forth in time" makes perfect sense for the exclusion principle, as it is undistinguishable, then you get a time loop instead of constant travel.

[@Feyser1970]

@@hyperduality2838 shut up

[@Ebruskaya]

Thank you very much for these videos on spin. I am finally enlightened. It was quite hard to visualize.