What is Quantum Mechanical Spin?

This video extends How Do Quantum Computers Work: • How Does a Quantum Com...
Prof. Morello explains why spin does not mean the particle is actually spinning. Subatomic particles like the electron, neutron, and proton have spin, which means they act like tiny bar magnets. This can be used in quantum computing applications.
We thank the UNSW School of Physics Demonstration Unit for providing the double pendulum.

[@wimamohammad5285]

we need more metal musician teaching science

[@divyanshugupta2422]

better

[@lineakristensen1821]

Quite fitting. This man is clearly a rockstar.

[@DSAK55]

Brain May

[@BrunoVasco]

I wanted to like this comment, but the number of likes on it was too apropriate for the theme _|m|

[@nyrdybyrd1702]

Angular momentum may be understood, but we may never know why Prof. Morello isn’t this video’s thumbnail. 🤷‍♂️

[@retepaskab]

thanks for the heart attack at 8:27

[@unknwn_usr3077]

retepaskab hahah

[@gokusan9967]

i felt it too

[@MSinAerospace]

yes can confirm... thank you for that terrible ending. I looked around my room wondering WTF was that!

[@omerufuk]

Same! 🤣

[@seedogreed]

exactly !!!

[@winkletter]

One step closer to understanding quantum mechanics. Seven billion more steps to go. :-)

[@rdmman9962]

Look at what he is stating is in the simplest form equalizing with math is where you loose the ideal .

[@vsiegel]

But you already know it's steps, not a continuum! Knowledge is quantized!

[@Fulikia]

"One step closer" reminds me of linkin park

[@atila8623]

😂😂😂😂👍👍👍👍

[@vishal2352]

One step closer to the edge I'm about to break

[@sparrowhawk81]

Uhm, yeah. Could you repeat the part where you said the things about the stuff?

[@seandafny]

Lol

[@victorflores502]

Homer Simpson

[@BigBez]

Super position is two energies cancelling out each other while “up up” is two energy’s harmonizing to create a charge

[@sadsalidhalskdjhsald]

This is great, brilliant in fact. I just have one question... what?

[@najla3370]

I have the same question XD

[@najla3370]

توني اشوفه XDXDXD

[@SF-li9kh]

I could never visualize quantum computing UNTIL he showed the double pendulum. Never seen that thing before. But NOW the picture is clearer

[@ishworshrestha3559]

@@najla3370 wgat

[@alanmcdonald7145]

lol

[@veritasium]

the 1/sqrt2 is a 'normalization' meaning that the probability of finding the electron in any state at all must be one. So that factor is there because otherwise you'd have a 200% chance of finding an electron in any state at all. The +/- signs he discusses are associated with having electrons in the same phase or opposite phase - the best analogy is the double pendulum.

[@Stargazer54321]

WOAH I didnt know you would be here

[@TheLethalDomain]

Holy shit this is the best explanation of normalization I have ever seen.

[@chinanwang8646]

Is it possible for spin to not be a probability and only a product of the nearest price acting upon it? The hidden variable would then be the spin of the surrounding particles? I understand that there would then be no link between two pairs since it is not based off of the others spin but can’t it be because two pairs can only travel in a quantises space where the spin of the surrounding particle would effect the spin on the other side of the surrounding and so forth until it reaches the the particle in the pair and coincidentally the length between them is always in such a way so that they are two opposite spins? This is for two particle pairs and I think you could predict spins of electrons in an atom judges by their angle from a line co-linear to the radius of the nucleus and perpendicular to the net magnetic field of the nucleus

[@aurelienyonrac]

What if it is space that is bending and what we call a particle is a point?😅

[@QuantumMechanicOne]

I trust your thought process

[@lupinearsenalALT]

This guy is sooooooo good but that doesn't keep my brains from blowing up into pieces and splattering everywhere in my dorm after the pendulum energy model.

[@omerufuk]

😁

[@michalkiwanuka938]

Fuck Turkey

[@maxmaxmaxcoolmaxmaxm]

Well, it's better than Africa...

[@lineakristensen1821]

Haha nice burn.

[@justinspitz2609]

I thought it was a terrible and confusing explanation I’m just gonna be honest. Which pendulum configuration corresponded to which state written on the board?????

[@blowmeliberal]

Unfortunately, the act of talking about or lecturing on quantum mechanics changes the description of quantum mechanics. Which is why it's so hard to understand.

[@diegoalves8043]

you sir just made my day

[@a64738]

Thanks for making me laugh :)

[@nikkitytom]

Thanks for a moment of much needed humor. I guess I really am learning something about quantum mechanics when I recognize that double slit conundrum.

[@benjaminparker8139]

My default response to this was to take everything you said literally and be insanely mind-blown at the possibility that quantum mechanics was inexplicable through a spoken language in 1-dimensional time. I have since come to understand that it is a joke. Lol.

[@sanjayg6842]

@@benjaminparker8139 🤯

[@NicklausSIR2]

The pendulum thing blew my mind. I guess it's clearer to me when you transpose it to the more intuitive newtonian mechanics.

[@poorlittlesheep4098]

+9000, that's exactly what i was gonna say then i scrolled down and saw your comment.

[@TLJGames]

NicklausSIR2 It was a nice classical depiction of the difference, but to really understand how incredible the singlet state is you need to have a look at the maths.

[@saamspam6127]

NicklausSIR2 the word transpose just made me cringe hard

[@aceman0000099]

@@saamspam6127 you're cringing at the use of overcomplicated terminology on a video by nerds for nerds?

[@krzykris]

The most clear, concise, and understandable explanation of spin I've heard. I wish I had this guy as my quantum mechanics professor 25 years ago.

[@stanimirborov3765]

yeah

[@takedonick101]

You understanding this concept now could be the culmination of all the different types of explanations of the concept you were exposed to. This video could be the last piece of the puzzle your brain needed to grasp.

[@justinspitz2609]

This just raised more questions than it answered. How did the double pendulum thing explain anything?

[@dorinori8189]

This blew my mind. And at the end it blew my eardrums

[@brandonbayangos6261]

thanks for the laugh

[@doodelay]

I will subscribe to see more of this guy, he was amazingly precise and interesting

[@stanimirborov3765]

yeah

[@lancetschirhart7676]

4:30 I love his face here, like "Pretty badass, right?"

[@fletcherwilson8499]

yes, please get rid of loud sound at 8:27 Veritasium for future videos. Great video, but people listen with headphones...

[@jonathanhart8730]

I literally jumped. I was so deeply entrenched in all this information I was processing and that sudden burst of sound was a slap to the face xD

[@josephcoon5809]

At least pin a comment warning people...

[@Homersonic]

The best teachers don't make their students feel like they're being talked down to, regardless of how basic or advanced their subject matter might be, and Professor Morello's definitely that kind of teacher.

[@derek]

haha, ok, point taken. I think the trouble may be the rest of the interview is too quiet but I'll try to get the balance right.

[@truthisthenewhatespeech9572]

🤣🤣🤣

[@ThomasJr]

what?

[@77mcgiver]

perhaps

[@bjarnivalur6330]

4:30 - 4:38 I love that little "k?" at the end of the explanation, as if what he said wasn't super counter-intuitive.

[@KFGChris333]

0:59 When I hear "purely quantum mechanical" I associate "Noone knows what it is, but that's just the way it is... accept it"

[@caseydavis6689]

He means that standard Newtonian physics (what we think of as common sense) will not describe the position of the two entangled electrons. They can be in two states simultaneously. This is one of the basic properties of quantum mechanics.

[@caseydavis6689]

In his words, this property is "purely quantum mechanical." It cannot be described by common sense. (Newtonian physics.)

[@KFGChris333]

I already knew that. What I meant is that quantum mechanics is based on axioms, and so it is, that there happens stuff that noone knows "how" or "why". Okay, someone could argue that we don't see vectors coming out from objects when we talk about Newton's axioms. (If he dares to ask the question, why is Newston's law as it is). But in Physics they are not taught as axioms rather they talk about "Newton's laws". Noone questions them really...If Newton's laws were thaugth as axioms and Physicist would admit even highlight that they are models of the reality, it would be much easier to understand QM. But often they surround QM with some vague scientific mumbojumbo e.g. "the explanation is purely quantummechanical" - That means that if QM axioms are accepted as true (they are because they tend to describe reality almost properly), there exist some mathematical equation, which spin comes out of. ps.Sorry for the length

[@AlericResident]

KFGChris333 I think he just means that there is not a classical explanation possible: no model that you'd recognize from every day life will suffice and give you an "intuitive" understanding. QM itself however is not synonym for "nobody knows what it is", QM is the most perfectly matching theory ever, very well defined and making accurate and precise predictions.

[@TurriPi]

KFGChris333 Trust me if you found the answer to quantum mechanics you'd be the biggest scientist genius since newton, perhaps even more than that.

[@joec.9833]

we need more of this person. the accent, the articulation in layman, its on point.

[@AlbertaClimber]

I could listen to this Prof. Morello all day. His clear and concise explanations are almost mesmerizing. Thankfully the pause button allows ample time to process everything he says. Really is an incredible video. Thank You for this!

[@aryesegal1988]

Can't say it enough: Absolutely amazing.. So clear.. Prof. Morello's ability to take a subject so non-intuitive and making everyone somewhat understand the laying foundations of it, is a true gift IMO... Great presentation, more of him, PLEASE! :)

[@stanimirborov3765]

yea

[@eucherenkov]

This guy is AMAZING to listen listen to. The way he explains things is just delicious.

[@sirlordford]

Andrea Morello is one of the best lecturers I've ever heard. His desire to communicate and ability to articulate complex concepts really create the perfect instructor.

[@TheVersionController]

This is the best laymans explanation of quantum spin I've heard, and I've heard many. I finally can grasp it. Thanks!

[@Woppieish]

Got confused pretty quickly.... But he explains this things better than anyone else I've heard. Post more videos with him please !

[@ChiaraCaratelli]

A really good explaination for a really controintuitive subject! Excellent work!!

[@daroay]

Veritasium... Never ever cut/edit the videos when interviewing this Doctor. Thanks for your Videos. Best channel ever.

[@NicknamedSin]

Professor Morello injected this knowledge into my brain in such a smooth way, I hardly realized I was actually understanding. Seriously awesome!

[@davep8221]

Wow. What a great teacher. This is the first time I understand spin. For some definition of understand ;-) He clearly loves what he does and loves sharing the knowledge. Thanks Professor.

[@liamchandler8860]

I'm amazed and inspired that you managed to explain spin so clearly in 8mins

[@stanimirborov3765]

!!

[@flowerlandofjohn]

What an extraordinary teacher Professor Morello is, every clip you posted with this guy just compels me to keep looking. Brilliant!

[@seblingtonw]

Fantastic work on your videos Derek, and Prof. Morello is really fascinating ! I love that you (among others like sixty simbols) keep delivering us videos on these kind of topics, keep it up !

[@mrmojorison2012]

I love that pendulum experiment! That's so cool!

[@yolanankaine6063]

The explanation with the pendulum was excellent

[@AlexBlate]

This is the best intuitive description of spin I've ever heard. Thank you! Please produce more videos on this subject and quantum computing :)

[@plainmainaccount5554]

I still have barely any idea what he’s saying...but I could listen to him all day. Actually entertaining as a teacher

[@usfghost]

That heavy thick accent, awesome

[@mihailazar2487]

yea...but what's up with that moustcache?

[@aceman0000099]

@@mihailazar2487 you mean beard

[@user-se7gt5yf8b]

What is Spin ? I think the answer is phase shift (= shift in coordinate). 1. I think the de Broglie waves of multiple particles in one quantum state are connected in series, and the each wave shift msλ at the connecting point. (ms:spin quantum number, λ:wave length)Let us consider a case in which two electrons are in one quantum state [n,l,ml,ms=+1/2]. The de Broglie wave of 1st electron shifts +λ/2 in coordinate. And the de Broglie wave of 2nd electron shifts +λ/2+λ/2 in coordinate. Accordingly the two waves destructively interfere. [the Pauli exclusion principle] 2. Suppose that two electrons are moving in a single orbit, and suppose that the de Broglie wave of one electron shifts +λ/2 in coordinate and the de Broglie wave of another electron shifts -λ/2 in coordinate. The two waves have the shift of exactly one wavelength, which leads to a constructive interference of the wave, making it possible for the two particles to move in the same orbit. [the 4th quantum number] 3. The variable of wave function Φ{φez･(r ×p)} in φ direction has angular momentum r ×p. Accordingly, the shift in coordinate msλ change the angular momentum as follows: ml(h/2π)→ ml(h/2π)+ms(h/2π). I'm sorry that I'm not good at English.

[@davidwuhrer6704]

Thank you. I find your explanation easier to understand than the one in the video.

[@boyisun]

That's rocket science to me.

[@Xxshadowman11xX]

I very much enjoy professor morello. His explanations are fantastic, and being interested in mechanical engineering and quantum mechanical processes, I enjoy his discussions. I'd love to hear more from him. Thanks!

[@jamieg2427]

Professor Andrea Morello gives the best intuitive explanations of phenomena that I've seen. His video for Veritasium on quantum computing is equally unrivaled; in but a few minutes, he makes understanding why quantum computing is so powerful---in a way that hours worth of other documentaries fail to do.

[@tubedude709]

Quantum computers gives you the answer to life, universe and everything, but only when your not observing it :D

[@Fulikia]

well said

[@karthik197]

@Red Dunkey you have multiple personality disorder

[@albond]

tubedude709 *you're

[@MeesterG]

We already know the answer to that. It's 42.

[@Cinnamon112]

So we're jus going to ignore that perfect circle he drew...yea sure

[@NorthernDG]

@0:23 for those wondering when.

[@djsaloboy]

What a great explanation! The dual pendulum analogy was magnificent

[@IsYitzach]

Thanks for the double pendulum demonstration. I really wanted to show that my PHYS 201 class when I discussed sound beats and the general usefulness of the harmonic oscillator. Now I have a video version I can show without having to ask for equipment.

[@rileyb1799]

My left ear enjoyed that scientists accent

[@Krish-jm6ve]

Normal Person : What is a quantum spin? Physicist : Slaps him hard on the face Normal Person : What ?! why !? My head is now spinning Physicist : Can you now explain what you mean by your head spinning ? Normal person : I now understood completely. Thank you !

[@Familia_nepal_nepal_do_mal12]

As a physics student I wish it was that easy.

[@yoseyoda]

A typical answer from a Zen master.

[@4ltrz555]

Sooooo, physicists aren't normal people. True tho.

[@AlericResident]

Andrea Morello is from now on my hero! I could listen hours and hours to him. He's so precise, correct and insight giving. Here is a man who understands these topics so well and can explain it so good, that he is clearly above the material. Please more of him!!!

[@emilrahbek1688]

I have been trying to make sense of the superposition for sooo long, and that pendulum explanation just made it all clear, thank you so much!

[@MR-nl8xr]

It's easy to understand with 2 objects, but try that with 1.

[@jBeastThink2ice]

This video is great, really appreciate your work!

[@timl2k11]

I can tell he knows quantum mechanics very well because I still have no idea what the hell QM spin is. (inside joke between me and Mr. Feynman)

[@whateverrandomnumber]

You talking about Richie?! Why, send him my regards!

[@iDEaXANA]

Or maybe he didn't explain it well

[@BenjaminSorvel]

I've seriously struggled with understanding quantum superposition before now. That double pendulum analogy really made me get it. Thumbs up!

[@RCStudiosca]

Good job. Some of the stuff you guys go over is way over my head, but I love it. Thank you.

[@DeanoDotson]

I liked how you use Newtonian to show quantum works. Thanks

[@joebidendidnotwintheelecti370]

So then if the particles where spinning in opposing directions and constantly changed directions, what sorts of things could come of such an unnatural state could it be a type of perpetual motion that produces energy?

[@nihilisticpotato3367]

whoa! That pendulum analogy was very enlightening, a great way to visualize superposition.

[@johnb4314]

Excellent analogies and explanations for general public. Wish I had had a physics prof like him in college. I hope we see more lectures for the general public from Prof. Morello.

[@origamigek]

I'm going to have to make a double pendulum.

[@apburner1]

Dracula does physics.

[@Kevin-sy8uf]

One, two, three electrons ha ha ha

[@SimonBuggeSiggaard]

I really think that this video is a good one! Especially because it tries to give a way to understand (or interpret) the spins. Also, this channel is becoming my favourite over Ve1, just because the acedemic level is higher. More quantum mechanics!

[@MrMagic1163]

Would love to see more vids with him, he explains things in a very good way!

[@iTracti0n]

I just keep rewinding 2:03 - 2:05 because he's like a cat, and something just caught his eye and he lost his attention. Or maybe he heard someone talking shit either one lol

[@earlspencer7863]

Lol he started talking about his lab which wasn't really pertinent.

[@magnetonerd4553]

Spin is not the magnetic field of the electron or other particles. Spin is an intrinsic property of elementary particles. The magnetic spin moment is determined by the spin of the particle and it tells us how the particle will behave when introduced to a magnetic field... A neutron has spin because it is a hadron. Hadrons are composite particles made up of elementary particles. Neutrons are made of quarks which in turn have their own spins. This is where the neutron, and analogously the proton, gets its spin from.

[@ruchi9917]

Can someone clear my doubt, If |a> and |b> are two basis states and the prob of both the states is 50% then we denote the total state of the e- as either 1/√2(|a> + |b>) and 1/√2(|a> - |b>). My doubt is, that the e- can also be in 1/√2( - |a> + |b>) and 1/√2(- |a> - |b>). Then why do we ignore these two states.

[@donfede75]

Prof Morello for president ! This is the best channel ever ! Thank you

[@MadaxeMunkeee]

I really enjoy listening to Professor Morello. The double pendulum was a really useful analogy!

[@erwindee7384]

Holy shit! 6:49! Yin & Yang! Ancient Aliens confirmed!

[@rajeas]

he has a charm...😍

[@hughholt121]

And other quarks.

[@Jake23897]

I think he is rather... strange.

[@SpaceCadet4Jesus]

He shows the beauty and the truth.

[@Wheau]

I love Professor Morello, he explains topics so well.

[@jaymyn88]

I love the pendulum demo. It's such a cleaver way to present this abstract quantum mechanical concepts to visual learners. Super! :)

[@paulgorowitz4007]

Tommy Wiseau?! Is that you?!

[@alexanderstrau4135]

But why are the two spins coupled two each other? I mean they are electrons from different phosphor atoms, right? Could somebody please explain me that.

[@razortongue9000]

I assumed he meant that they are coupled simply by comparing them.

[@robertofontiglia4148]

As a simple way to put it, you have to remember that they have magnetic dipoles. So they generate a tiny magnetic field, and the other spin tends to line up with it, just as they want to line up with the other spin... They end up oscillating forever, just like the two pendulums...

[@handris99]

I think they are coupled by each other because they are entangled. They entangle them before they put them in I think.

[@robertofontiglia4148]

Deep Space Angel It does not have much to do with entanglement. If you look at the math, that's just how it works out : when you look at, say, two electrons, there is an interaction between their dipoles - they tend to line up. (That's a classical explanation, but then, the development for this is semi-classical : we derive the Hamiltonian from the classical formulas for the interaction between two magnetic dipoles...)

[@Nilguiri]

Fantastic. I loved the double pendulum superposition analogy.

[@FlorianFahrenberger]

This is actually very nicely explained. I'd love to hear a lecture of his some time.

[@Hyporama]

i find his explanations pretty easy to get

[@SigSelect]

you must have missed something

[@Hyporama]

Yup, that's what they say..

[@zach2302]

Scared me at the end

[@MogaTange]

The prof. Morello videos are some of the best I’ve seen, does he have his own channel?

[@Martsigras]

I love this dude. He is so good at making analogies and helping you understand

[@DamianBehymer]

Does he have a Hungarian accent?

[@geneellis3158]

a tad bit

[@location4898]

Damian Dootdoot italian

[@marcalbertmusic]

I had to comment because the video was at 666 comments

[@TomOConnorBassGuitar]

Thanks for these videos, they're great! Most other videos on this give you a very basic answer, not really answering anything. It's nice to be explained it more in terms of the actual maths, as even though you don't understand every single bit of it straight away, the big picture makes a lot more sense.

[@TheRelain]

Love these videos Derek, good job!

[@shirafingerer9437]

Can I take quantum mechanics with him instead of with my professor? xD

[@seafreitas1040]

I see said the blind man

[@TheChzoronzon]

I'm obtuse, said the edgy kid

[@1nsiderr]

Double-pendulum = entangled state. Great analogy. Prof. Morello explains stuff better than any teacher I've ever had. I love this!

[@Defeshh]

Awesome! I love these videos getting deep into what's more interesting. Sometimes it feels like the videos (in general, scientific divulgation videos) should get more information about the topics exposed. Thank you for this video.

[@unknwn_usr3077]

I like listening to Russian accent 😂 xD; D

[@Rugbystu14]

He is Italian...

[@almanduku9043]

@@Rugbystu14 😂😂

[@incendiablo]

Professor Morello is so awesome!! More videos with him, please

[@KeiVal666]

He is such an incredibly good teacher. Wish we had more people like him.

[@anastasiaoverton720]

Morello is an excellent teacher. I'd like to see his lectures unedited.

[@jb8517]

Great explanation, Mr. Nugent.

[@JustinAlexanderBell]

We need more of these videos!

[@engineer15426378]

Thank you so much for this video. Professor Morello is an inspiration. I would love to study under him.

[@NedTheDread]

I'm always wanted to know what exactly the spin was really about... now I know, and actually understand! This guy is sooooo great at explaining things, it's unbelievable!

[@SandWraith123]

The only thing better than listening to Professor Morello? Listening to two Professor Morellos at the same time.

[@doneche1]

This gentleman does a fantastic job explaining these concepts. :)

[@seanattikus]

This guy is awesome. I love watching videos with him in them

[@Vork81]

Cool stuff, it shows some real skill to make something so hard to graps easier to understand.

[@svran1234]

Wow the pendulum example helped me a lot with intuition! Thanks so much!

[@JoeBribiesca]

Very much appreciated! IMO, the audio during the interview was fine, and I'm not saying I don't like the sound effect, but it's just that they were both a little far from each other in dB. Awesome recent topics, btw, and I freakin' LOVE 2veritasium since you tend to dig a little more into the topics. Great idea! =)

[@Jinx313]

I subscribed to Ve2 only because of the videos with Prof. Morello. I hope this wasn't the last one with him; he does a great job in explaining this pretty complicated subject.

[@yusufshaik]

I had to watch this at 5 second intervals about 5 times (while taking notes) just to understand this well. Great video, Very Informative if you can actually understand whats going on