What Schrödinger’s cat REALLY means

[@ScienceAsylum]

Yeah, the "shut up and calculate" crowd is a huge chunk of the physics community. Quantum mechanics makes perfect sense if you just focus on the math (which is what my last video was about). It only gets weird when you start asking what it means about reality, so a lot of physicists just choose not to 🤷‍♂️. Personally, I think/hope there's a happy compromise in the middle. Maybe we can ask deeper questions _without_ imposing our classical notions onto quantum mechanics? I don't pretend to know exactly where that compromise is though. P.S. Nice self-promotion with the plushies 😉👌

[@jagadishk4513]

Did you see alpha phoenix's recent video

[@christopherknight4908]

The only way I've been able to make sense of this is accepting that I am also in a superposition of having seen the cat dead and having seen the cat alive.

[@ScienceAsylum]

@@jagadishk4513 Oh! I knew this one was coming, but didn't know Brian finally released it today. I'll have to go check it out.

[@ScienceAsylum]

@Abraham Brandon Purnama I get where you're coming from. Asking "why?" is the most exciting part of physics. It's just that quantum mechanics is so weird and so new that we don't have the answers to the question we want to ask. Without those answers, your questions will just lead you in circles.

[@ScienceAsylum]

@@christopherknight4908 That is certainly one interpretation, but not the only valid one.

[@osaka_phong]

I have a Schrodinger's dog. When he wants to get outside, he stands in front of the door. But if I open the door, there is a 50% chance he will be still standing there, never moving out, and I cannot know what his actual decision will be until i open the door.

[@jonathancamp7190]

Schrodinger really had a dog, named Bruchie. I don't know if he ever had a cat.

[@robj1328]

What you're describing there is a cat.....most definitely a cat.

[@davesutherland1864]

I have a similar dog. Maybe they are entangled and what you dog does, mine does the opposite.

[@Klostergeist007]

That’s absolutely THE best comment I have read in a long time. Also I have a dog. Physics Girls draws the right kind of crowd ! I will go now into Sunday superposition: a) wanting to do something and b) totally inert at the same time. Happy Phyicsing -|-|-

[@jamesdriscoll_tmp1515]

My cat goes to the back door and if the weather isn't what he wants he goes to the front door, looking for the door into summer.

[@Axe_Edge]

I asked a librarian if she had a book about Pavlov's Dog and Schrodinger's cat. She said it rang a bell but wasn't sure if it was there or not.

[@tayleanruatha]

😂😂😂😂😂😂

[@NewtonMD]

It was in a superposition of there and not there

[@jadespider7526]

check the return's cart, if you can't find it, it's usually still on the cart.

[@rustycherkas8229]

Sounds like your librarian's name is Heisenberg... 😂

[@ohasis8331]

@@jadespider7526 check the return's cart, if you can't find it, it's usually still on the cat.

[@stevenemert837]

Awww. The cat plushie and the dead or alive pin are both sold out already! Please make more! They are so cute!

[@kigufox]

I haven't checked the store yet, for all I know they might still be available.

[@psymoozoo]

I second this

[@MrDonkrypton]

It's sold out on the first day! On the first day! We'll need more of them!

[@JaceFuse]

The video wasn't even finished before I googled the plushie, found the store, and was disappointed to discover they were sold out.

[@seriousthree6071]

I umpteenth it. WE NEED MOAR PLUSHIES! What do we want? More plushies! When do we want them? NOW!

[@CM-yz3ze]

One thing I enjoy about this channel, is you're comfortable saying that there isn't an answer. It seems really hard for some specialists to just say "I don't know" sometimes.

[@wild_lee_coyote]

I like the fact that you chose yellow and blue because those colors also can be in a superposition. They don’t mix in the human mind (for most people) and so it is either yellow or blue, but never a yellowish blue or a bluish yellow. Give your eye one yellow and the other eye one blue and you can’t mix those colors. It’s a weird optical superposition were you can see both colors at the same time but they are still separate colors

[@herculydia]

Tell that to UCLA Bruins

[@hinatamasaki9991]

It’s important to note that the electrons doesn’t “know” if they’re seen by someone. By measuring something (like electrons or protons reflecting off it), there's a physical interaction with the object. That interaction is what causes the electron to “ pick a side.” A human isn’t necessary for the wave function to collapse. Edit: really recommend watching ‘Science Asylum’, specifically about superposition

[@Bodhi1satva]

How is “seeing” physical or physically interacting with anything?

[@rmsgrey]

@@Bodhi1satva The point is that your quantum state is affected by the electron's (or the cat's) through an interaction, meaning that your quantum state shares the same superposition as the cat (or electron). Before opening the box, there are two separate quantum systems in the room - there's the contents of the box (cat, radioactive source, poison, etc) and there's everything outside the box. When you open the box, the two systems mix pretty quickly, and within a fraction of a second, your quantum state is matched up with that of the cat (just like the cat's was matched with the poison's - the cat's alive or dead and the poison is sealed or released, but you can't have a dead cat and sealed poison). All the talk of observations and collapsing wave functions comes from a mental model that ignores the fact that people are quantum systems too, and when a photon enters someone's eye and creates an electrochemical chain reaction that propagates into their brain, that just brings them into the same wider quantum system. Depending on how you interpret the maths, either there are other versions of that person out there, seeing different photons, in a superposition with them, or there is just the one actual quantum state that acts as though there was a superposition. Either way, the observer and whatever they're looking at are in a shared quantum state, which is why you never see an actual superposition in daily life.

[@Bodhi1satva]

@@rmsgrey THANK YOU! That’s the first and best explanation I have ever heard or read actually!

[@BassandoForte]

@@rmsgrey - So that would suggest realty is like a rainbow - People see their own from their own perspective... 😱 So how would anyone know what realty is..?? This opens up a huge can of worms in philosophy more than physics you understand lol... 🤣

[@rmsgrey]

@@BassandoForte Get back to me when you find a philosopher that can establish that reality is in the first place. Last I heard, no-one had got beyond "my subjective experience of questioning my own existence implies I exist to have a subjective experience (and to question)" though it's more commonly phrased rather more briefly.

[@themanhimself3]

Don't cut out the long winded parts. They are absolutely the best part. You should extend them.

[@arthurhamlin6594]

Maybe what we really need is either the "outakes reel" or a second video that is the "extended version" just like they do with BluRays

[@calholli]

Yes.. Show your flaws in contradictions in the ramblings.. We need to see it.

[@UnanimousDelivers]

She all but did. This whole video was "what's 2+2. And the truth is it's really really complicated. So ...what is 2+2? Now .....2+2 ....look at this 2 plushie, isn't it cute? It's so cute. OK so ....numbers have been complicated for years. Lots of people have been thinking about numbers. So to answer what 2+2 is we have to look at addition. When you add things together, you get new things, and when you put things together in ways that create new things in new ways that make numbers, it's 4. So there's lots of numbers and addition is amazing. So now you know."

[@calholli]

@@UnanimousDelivers But 2+2=5 .. everyone knows that

[@pvic6959]

im not lying when i say: "I can and will happily listen to her happily and enthusiastically explain literally anything". just listening to her is so fun and nice

[@digitheadRex]

Thank you, thank you, thank you Dianna. For years I have been telling people that Schrödinger was making fun of Heisenberg and the ideas of quantum physics. My physics prof debated me for a few hours on how Schrödinger was serious and not at the same time. You made a great discussion a lot easier to digest. Thank you.

[@FriedRice3519]

lol, what you said is true. And some ppl i've come across, especially chidren with too much internet access use Schrödinger theory as a way to say they can shift realities 😭😂 honey no, ur just too imaginative. I remember was talking to someone abt this and this random kid popped up and said she can reality shift bc according to Schrödinger theory, she can interpret reality, blah blah, idrc to remember. Then the brat started cursing everyone out and said "ok but i'm 11 and I can reality shift" 😂

[@TheJimSkipper]

Schrödinger literally called the idea absurd and the the Copenhagen interpretation was ridiculous. Like Galileo, he was forced to recant, but didn’t change his mind. Evidence continues to grow that physics really doesn’t understand what is going on.

[@michaelb1761]

​@@TheJimSkipper Are you questioning the deity of physicists? Now, now, don't question the new orthodoxy. And, don't expect them to explain themselves. That's something that I really appreciated about Einstein, he wrote a book that anyone could understand, rather than telling people that he was smarter than them and to stop asking questions.

[@SahilGhosh]

​@@TheJimSkipperfalse

[@patcheckert295]

I hope you heal quickly and well! I love your videos

[@lynnettetorres7338]

The passion that she talks about this is mesmerizing 🥰

[@rmknfklh5324]

That is the main reason I subsribed to her channel. Her passion and drive is absolutely addictive, in a good way.

[@Teddy_Miljard_of_Finland]

I agree ❣️

[@StefanSteinerWA]

We all love her.

[@celam1244]

Truly!

[@hallonsylt6729]

No it isn't!

[@ferdievanschalkwyk1669]

The modern version of this is the USB port. You can try it one way round and it won't fit, flip it over and it still won't fit, then you look at it and insert it the right way. Until you look at it, it's in its superposition where both the top and bottom halves are blocked off.

[@Arthera0]

Honestly that would explain this issue

[@scarletspidernz]

Universal Schrödinger's Baffle ;)

[@bierrollerful]

Schrödinger's USB sticks doesn't quite have the ring to it, though.

[@maxine_q]

Or you know the orientation of the port on your computer (this would be easier if they followed a standard), and the orientation of your device (this would be easier if they followed a standard), and it fits first try, always.

[@ferdievanschalkwyk1669]

@@maxine_q ah, but you see, that means you have forward knowledge, which changes the outcome.

[@MaryAnnNytowl]

LOL, the Shroedinger's Cat "choice" on the order of the pins is just hilarious! It's probably way beyond my fixed income budget, but I'm gonna dream! Even a poor gal's gotta have dreams!

[@benc8386]

Yes but does she really use a quantum random number generator to decide which one to ship out? This is important.

[@ChrisBigBad]

no worries. it's sold out anyway..

[@Wolf-ln1ml]

It would have been nice to mention that "observing" an electron during the Double Slit experiment isn't a passive process, it involves interacting with the electron in ways that can easily change it's behaviour. Other than that, wonderful explanations and just contagious enthusiasm as usual 🥰

[@maltflesh]

so in other words is easy for anyone to manipulate electrons by pure observation alone.

[@Wolf-ln1ml]

@@maltflesh If you consider it "easy" to acquire and set up the necessary equipment, then yeah... But in that case, it's also easy for anyone to experience weightlessness, all you have to do is go in a very specific parabolic flight path with exactly the right acceleration. "Easy"...

[@maltflesh]

@@Wolf-ln1ml but were just talking about electrons and observing them, not a comparison

[@Wolf-ln1ml]

@@maltflesh So what? I addressed your comment, then _added_ a comparison to get my point across in another way.

[@maltflesh]

@@Wolf-ln1ml the point is we may be more capable than 'your' "equipment". the underlying chuckle on my behalf was for the reader to read between the lines and come to the conclusion that we manipulate matter based on our simply and "easily" observing it alone. i commented to see where it would go discussion wise.....nowhere apparently.

[@tim-tim-timmy6571]

Not really easy to understand but the work of Serge Haroche on decoherence (transition from superimposed states of particles to the state we measure) is really interesting. He got the nobel prize in 2012 for his work.

[@michaelroy1631]

Thank you!! As a chemist who deals with quantum mechanics all the time, the distinction between the *mathematical model* and the *philosophical interpretation* is so important, and the context for Schrodinger's Cat is necessary to understanding how bizarre everything is with QM.

[@madisondampier3389]

The state of the cat's aliveness or deadness still must follow the natural laws according to how a cat would biologically become poisoned and die. What the thought experiment suggests is that, *merely in the context of our awareness of the cat's state*, there is a 50/50 probability of it being alive or dead upon observing it at the half-life of that radioactive atom's element. Now that's not entirely true, given you can open the box to find a state that the cat is *dying*, or even see the hammer drop onto the poison. However, on the level of the radioactive atom itself, without fine enough instruments to measure the state of the atom in its period of decay or knowledge of how this process goes about, the best guess we have at coming to any sort of explanation as to its state is to say that it is probabilistic, and we have previously measured the rate of decay in terms of the half-life of elements through observation of large masses of said elements and their radioactivity in a closed system, giving us a time-frame as to when we might expect, at the half-life interval, the 50/50 probability of that atom's decay, upon observation. Does that make sense?

[@charliedesperado8262]

Hi I'm really interested in knowing about quantum mechanics, do you have a lay persons example of something that you can prove superpositioning is real? Not a mathmatical model but a real world example of it happening that I could research please?

[@JonVlogs123]

Yup 😎👍

[@brucecrane9605]

I'm glad I live in the larger physical world and not the confusing Quantum world. Physic Girl, did help me understand the issue better. I have nothing smart to add. Thanks.

[@PloverTechOfficial]

Quantum mechanics gives even the people who understand it existential crises

[@lukasmiller8531]

Oh please this has been explained by every single science channel on youtube before , probably by her as well

[@EdwardChan.999]

You could check out Veritasium's video on the Pilot Wave Theory, and PBS Space Time's video on the Many Worlds Theory! Again, nobody knows what is actually going on, but it is still very interesting to hear about all those different interpretations :)

[@bierrollerful]

But...in quantum world, you could tunnel through walls. And if you didn't want to do household chores, you could _literally_ be dead until mom/your SO looks away again.

[@jensphiliphohmann1876]

You live in a quantum world - just on the scale of large quantum numbers where some odd behaviour is erased by decoherence. In a classical world, not even matter would exist and the laws chemistry would never had occurred.

[@johnchessant3012]

5:45 This relates to the Heisenberg uncertainty principle. By putting the detector there you get more precision on the electron's position, which means you have less precision on its momentum. Physically, what's happening is your detector is using photons to detect the electron and those photons are affecting its momentum, thus changing the experiment.

[@danielclv97]

I don't think this is related to Heisenberg uncertainty principle. By measuring the exact position, you loose information about the momentum, thus you don't know anymore in which direction the electron goes, so if it was only that at play, by not measuring you should get two lines, and by measuring the position you should get two fuzzier lines. I think veritasium did a good example where he had a laser beam passing through a small gap, and as he was reducing the gap's size after a certain amount, the light on the screen started to widen, making a thicker line. Thus, the most popular theory is that, by observing the electron you collapse the wave-function

[@danilooliveira6580]

not exactly, the detector collapses the wave function. though I'm not sure if its in all interpretations, it makes the wave decoherent, so it can't interfere with itself anymore.

[@Vector_Ze]

@@angelina-ng6xw I'm with KZbin on that, BE GONE spammer. Reported, for what little that's worth.

[@Sivah_Akash]

To our brain used to our "macro" world, that explanation does make the most intuitive sense I guess.

[@NealMiskinMusic]

I am a total layperson with respect to quantum mechanics, but my own interpretation of the Observer Paradox that our instrumentation for observing quantum particles is inadequate. It's like trying to measure the path of a baseball by throwing it at a net and measuring the vibrations in the net. We can gain a certain amount of information about the ball from how the net vibrates, but the baseball changes its trajectory when it hits the net which screws up any subsequent measurement we want to make of the ball's original trajectory.

[@arunbupathy]

To me, the more fascinating example of superposition is concerning the polarization of light. If you put two polarizers perpendicular to each other you don't see any light output, but when you put a third polarizer in between, at an angle to the other two, you see light. The math works out, but it's totally not intuitive! Love your videos!

[@GSBarlev]

I realize this is an old video and an old comment, but the interpretation I was taught for the polarization phenomenon wasn't that hard to understand: It's not that polarizers "let through" a certain number of photons, it's that they absorb--for all intents and purposes, _destroy_--all incoming photons, and then *re-transmit new photons* at a certain efficiency across its own polarization axis. It's kind of like if you're trying to output video from your phone to a 1950s era TV. Not too many USB-C to RF adapters out there, but if you get a DP-Alt to HDMI converter, an HDMI to RCA box and an RCA to RF transformer, you can get the signal through.

[@thesjkexperience]

Thank you. That slit experiment finally makes sense! Your water model made me think of how sound/frequency/guitar can be modified/combed…. and now I get it.

[@billyiswaiting]

These are my favorite videos from you! I love this explaining style :)

[@我主也]

5:52 - an important point that you did not mention is that the "detected" results all sum together to create an interference pattern as if there was no detection happening, and this removes a lot of the mystery of why two different patterns can be produced: they are the same pattern analysed differently.

[@markcoffey9437]

🤓!!!🤯

[@paulkubin]

You may have answered a question I had: what if you "look at" or measure only EVERY OTHER electron in the double slit experiement? Would you get just the two slits for the obvserved ones and the bands distribution for all the others? And would those two slits coincide with the middle two slits in the distribution?

[@justscratchingrocks1947]

@@paulkubin It's not even the slits or the electron that is important in my comments...it's the effect it has and how probable it is to happen to us in our confined spherical box we cats are all in...you are speaking at a quantum level of this point in time from where we observe...I am speaking of us in regards to the Quantum Planetary Level and life that lives in it on at the Atomic Scale

[@s2g234]

Water came out of my nose when I saw the typo of "Wave Function". Always love your candid explanations!

[@jasondashney]

That was the second typo of the video. The other one was the misspelling of because at 2:19. You don't often see 2 in the same video by a smartypants. The word I is missing from the audio at 5:11 as well.

[@tvtitlechampion3238]

"Fuction"

[@theophrastus3.056]

Through one nostril, the other, or both? We need to know.

[@winstonsmith11]

@@theophrastus3.056 I suppose it depends on whether it was observed or not.

[@mhagnew]

@@theophrastus3.056 And did the water form two streams or four?

[@fresetu]

Well, I remembered more about this topic than I thought I would! Makes me proud to have such a good memory (and enough interest) after all of those decades. To whoever picked the joke at the end: You did good! 😂

[@bobpeters61]

Yeah, that Schrodinger's Cat plushie is absolutely adorable. Thanks for the link to buy one.

[@stevotheoneandonly]

Love these short films, but you need to correct a really bad spelling mistake --- Wave Function ( 4:29 ) and not what is displayed. Keep up the good work.

[@CraigGood]

It's just a typo.

[@danielroder830]

The thing with the cat in the box is, that opening the box and looking inside is not the moment it is "measured" or "observed". The state of the system is already determined when the decay happened and interacted with something else. The moment the wavefunction interacts with something it breaks down and is determined. So the cat is either dead or alive but not both.

[@juzoli]

Underrated comment. Macroscopic object, with a structure of many particles, can NOT be in superposition. The cat is only a metaphor for elementary particles.

[@wtpollard]

Yes! I was in the middle of adding a comment to make this point, when I saw your response. The other point, though, is that quantum mechanics tells you that the state of any physical system is described by a wavefunction, until that wavefunction is "collapsed" by a measurement. It's describing an isolated system with external observers, but there's no natural boundary between those two. So, is there a wavefunction that describes the entire universe? If not, why not? If so, what could cause it to collapse? In physics, when you're working at the boundary between quantum-mechanical and classical systems, you use density matrices to describe your statistical collection of quantum-mechanical objects, but that requires you to define a arbitrary boundary on the size of the subsystems you're going to describe quantum mechanically.

[@juzoli]

@@wtpollard “Is there a wave function that describe the entire universe?” The wave function doesn’t go away when it “collapses”. It evolves. After your measurement, it is still a wave function, which you can measure again. Measurement is an interaction between 2 particles. One is what you are measuring, and the other is your measurement device. When 2 particles interact, their wave function is combined, information is exchanged, and they have new wave function as an outcome. The universe is the sum of ALL wave functions which are continuously evolving. But how do you take a snapshot, when you can’t define a universal moment?

[@wtpollard]

@@juzoli The theory I was exposed to (as a theoretical chemist) only talked about the evolution of a system from "coherence" (a pure wavefunction) to a statistical state (probabilities of being in different quantum states). Is there a paper, or book somewhere that describes that process in terms of an overall, evolving wavefunction?

[@juzoli]

@@wtpollard PBS SpaceTime has a video about it somewhere in the last 1 year. I will post if I find it Anyway, it is nothing new in it, it is just a consequence of how basic quantum physics works. If you measure the state of the electron, it will not “stay” there permanently. You will find it at a different position at each measurement. So it is ALWAYS a wave function of the probability cloud, and you cannot change that. Your measurement reveals a specific position, but it stays as a wave function regardless. A different wave function though. You don’t need anything else than basic quantum physics for that. But basic quantum physics is complicated to begin with:D

[@Roberto-REME]

Dianna, I love your videos for their knowledge value, clarity of thought as well as entertaining.

[@Teddy_Miljard_of_Finland]

Same thoughts! ❣️

[@Corn0nTheCobb]

Same thoughts! ❣️

[@AJ5]

I don't normally watch sponsor bits, but you did a good job catching my attention!!

[@IROC400]

Diana could give a presentation about all the bad decisions I've made, and I would still watch it.

[@Gabriel-um9hm]

I would love to see Physics Girl doing an episode on the delayed eraser experiment! I also recommend looking at "The Delayed Choice Quantum Eraser, Debunked" by Sabine Hossenfelder.

[@wings2585]

peraonally I think Sabine is a materialist who has a strong bias towards materialism, which generally is inclined in the belief that Consciousness is just an emergent property of particles moving. As such, viewed from the lense of materialists, thw delayed choice will seem to be debunked. But I think that's the problem. Materialists are unwilling to detach from their perspective and instead, interpret newer types of experimental reaulta from the same old fixed perspective

[@Belgarathe]

I have always had an infinity for physics. This is probably the best video explaining the whole thought experiment. It also shows how the study of physics isn’t a dead end but a continuous back and forth debate. Thank you

[@Nilguiri]

An affinity, perhaps?

[@jmodified]

@@Nilguiri I've heard it both ways.

[@ctakitimu]

@@jmodified Then you've heard it used correctly half the time

[@jmodified]

@@ctakitimu It's a standard joke.

[@techommar7468]

I've been researching about Quantum Mechanics for a few days... trying to wrap my mind around Schrödinger’s Cat, this is exactly what I needed... Thanks Physics Girl!!!

[@NikiCanotas]

I so want the pins , keep making them... Team, order more of her stuff and we can support her by buying stuff like these cats. Prayers of healing.

[@tubamacmac]

The idea of buying the Cat Pin and not knowing what it is, and then keeping it in that state of superposition is BRILLIANT. I want to get one just to add to the entropy of the universe!

[@mygirldarby]

Many things, movements, religions, theories, etc., were named by their detractors. The Quakers were called that because people would say they would "quake" when influenced by the Holy Spirit. The Big Bang was named by astronomer Fred Hoyle who hated the idea and labeled it the "big bang" to disparage the concept. Even the art movement "impressionism" was initially a criticism of the style.

[@liamclarke64]

I wholeheartedly love your output; I just wish I could wholebrainedly keep up with half of what you so beautifully explain.

[@TheLowstef]

As a professional physics educator (with a PhD in physics education no less) I've been explaining this for years to different people (including a general audience for an event at a science festival). My approach is usually along the lines of "Here's what we know for sure, because we've run the experiments. Here's the math that explains it PERFECTLY (up to the levels of precision we've achieved, which are insane). Here are some interpretations of this math and why they are weird. It's weird y'all!"

[@madisondampier3389]

The more you know, the more things you realize happen purely by chance. Thank you for taking the time to learn and share your understanding of the world.

[@tracyalan7201]

Old as I am, I enjoy watching Physics Girl explaining scientific things, which I find interesting. This video is one of those while I love watching, gives me a headache thinking about physics and why I stopped taking science classes as soon as I could in high school and never in college. Good video. Nice cool cats too. Mahalo.

[@piccalillipit9211]

*MY LOVE OF THE DOUBLESLIT EXPERIMENT* is off the charts - I think it is the most wonderful glimpse into how truly strange the world really is...

[@clintgordon6898]

Thank you for all your work. I enjoy your videos, and most of them make sense to me. Thank you especially for what I am describing as my own new superposition. I now understand the cat in the box thought experiment and at the same time I still do not understand it at all. Keep up the good work.

[@Teddy_Miljard_of_Finland]

My cat didn't get the idea 🤔 ❣️

[@brandonbuckles826]

I really like your channel! I've always been so fascinated by a lot of the topics you cover, but don't know how to process what I read about it sometimes, so that it makes sense to me. Having someone who knows this stuff and knows how to deliver it to Joe Schmoe's like me is pretty cool 😎

[@techondrugs8388]

Schrodinger killed his cat when he was just 9. Seventeen years later the cat returned from the dead stood up on 2 of its legs and proceeded to tell him the secrets of quantum physics whith an Irish accent got down on all fours and died again. Thanks.

[@bajajoes1]

Schrodinger's cat experiment only works as it does because you left 1 dimension out. If the dimension of TIME is added it is solvable. Easily.

[@CallMeChato]

Technically you don’t have to put anything into your shipped box. As long as we don’t open it, it might have the cat in it or not.

[@kluangh1tam]

What I understand from this video is there are two separate reaction among the physicists when it comes to theoretical problems. One took the principal of believing in the math from other theories that have been proven, and not questioning it. Others would simply need to conduct the experiment themselves to get definite answers and wont accept the just the theoretical calculations. And Schrödinger’s cat plushy was so cute, it was so wrong to be that cute for a cat in a superposition.

[@arnie1020]

Amazing and well explained. Thank you! The part about electrons shocked me 🤯

[@Teddy_Miljard_of_Finland]

I was shocked by the box! ❣️

[@TehJumpingJawa]

@10:40 "If you never open the box, then you'll never know whether it's dead or alive." Not true; the state of the box contents is entangled with the rest of the universe in many many places. Most obviously with the person who packed the box, but also more fundamentally with the energy states of the photons that bounced off it before it entered the box. That's the flaw with Schroedinger's Cat thought experiment; it's impossible for a macroscopic object such as a Cat to enter a box without becoming entangled with some aspect of the surrounding universe. Moreover it's impossible for the box itself to create perfect isolation between the exterior & interior of the box; we as observers are already entangled with the state of the Cat.

[@crashman2062]

Quantum entanglement has absolutely nothing to do with a person not knowing what is in a closed box. Entanglement does nothing to inform us of the status of an unseen object.

[@psilver063]

I think the last part about some type of measurement on the electron is the most amazing part of that experiment.

[@wmstuckey]

Fun introduction to superposition via Schrodinger's Cat. Let me add something interesting using quantum information theory. What people fail to mention when talking about quantum superposition using Schrodinger's Cat is the difference between a classical bit of information (like a computer bit being on or off) and a quantum bit of information (a qubit). Both bits produce one of two outcomes when queried (measured), but a classical bit has only one measurement possible while a qubit can be measured in many different ways (infinitely many, actually), each with two possible outcomes. For example, the double-slit experiment you used in the video is a qubit. When you put the detector screen right up against the slits the electron’s location is being measured, i.e., slit 1 or slit 2. As you move the screen away from the slits, the likelihood that a detection event is associated with slit 1 on the right, say, is higher if the detection event is on the right side of the detector screen. However, once the detector screen is very very far away from the slits (infinitely far, if you want to be exact), a detection event on the right side or left side of the detector screen is equally likely to be associated with slit 1 (50%) as it is to be associated with slit 2 (50%). The two outcomes in that measurement are the constructive interference fringes and the destructive interference fringes. This is actually a momentum measurement, which is the complement to a position measurement. That means its outcomes are a 50-50 superposition of the two possible position outcomes, e.g., |constructive> = |slit 1> + |slit 2>. This is exactly what you hear people say about Schrodinger's Cat, i.e., you open the box and find the cat is dead with 50% probability or find the cat is alive with 50% probability. With that information alone, Schrodinger's Cat could be a classical bit or a qubit. If Schrodinger's Cat is a qubit, then there must be a measurement of the cat-box system like the momentum measurement producing the state |constructive> = |slit 1> + |slit 2>. We know the measurement "open the box" producing "Live Cat"-"Dead Cat" results in 50-50 fashion is analogous to the position measurement in the double-slit experiment, so what is the measurement of the cat-box system with an outcome corresponding to |Live Cat> + |Dead Cat> corresponding to the momentum measurement in the double-slit experiment? And what does its outcome mean physically? If you can't articulate that measurement and outcome of the cat-box system, and every possible measurement between that measurement and the "open the box" measurement (like moving the detector screen continuously away from the slits), then the cat-box system is just a classical bit ... like opening a box to find a ball or no ball. No quantum superposition there 🙂 To read more about the quantum information approach to entanglement for the "general reader," see "Einstein's Entanglement: Bell Inequalities, Relativity, and the Qubit" due out in June 2024 with Oxford UP.

[@kelton5020]

Get well soon

[@e.dbogan6266]

I love quantum physucs! Don't understand it (who does?!), but love it nonetheless! Thanks for bringing up the double-slit experiment; I have spent way too much time on this crazy thing (I'm not getting any younger). Love your channel. Keep bringing your videos.

[@maxine_q]

Anyone that claims to understand quantum physics, doesn't.

[@frede1905]

If you wanna learn QM, you need to buy a textbook on it. Understanding the concepts of QM without any mathematics is virtually impossible, I'm afraid.

[@e.dbogan6266]

@@frede1905 Thanks.

[@con-f-use]

The thing is, in none of the interpretations is the cat actually in a superposition. Dianna mentioned, that the act of measuring causes the wave function to collapse. It's why the electrons form a discrete pattern when measured directly at one of the slits. But what is measurement? In this context a measurement is any coupling of your quantum system (the decay product in Schrödingers experiment) with a macroscopic system. That macroscopic system is the Geiger-Muller counter. So even in the thought experiment, the quantum system is measured, the wave function collapses and the get is either dead or alive, never a superposition of both. The question which interpretation is correct, however, still remains. Fun fact: There was even a debate at one time if this "magical concept" on measurement requires consciousness, i.e. if and observing mind might make a measurement. It doesn't, it's just coupling to a large enough system so that quantum effects have a very discrete, deterministic (one might say sharp) average with almost no deviation.

[@madisondampier3389]

Essentially, you can't make a measurement with non-interacting particles. Why light itself doesn't disrupt the wave pattern, is just that it exists in a state that doesn't change the electron's wavefunction. The two can pass through each other without engaging in entanglement in the case of the electron absorbing and re-emitting the photon that just entered its probabilistic waveform. To imply detection would mean that the electron emitted a force/particle at a precise location in space, thus determining that it has definitely entered one slit or the other, and centering its waveform on that location, where otherwise the waveform would be spread across both slits probabilistically and able to interfere with itself in the wavelike pattern. The detection "glues" the waveform to a definite location, and because the detector always detects an electron that passes through a slit, it always interferes. The wavelike pattern now exists at the level of the length of intervals that electrons enter either the left slit or the right slit, instead of in the wave pattern itself. It tends stronger towards the middle of 50/50 odds, with rare strings of 2+ left or right, getting rarer the more extreme the length of the string.

[@gordonstull1962]

I like your observation of superposition, at first I thought that the non-physical cat, was the superposition, but now I know that superposition is the inbetween factor that exists between the two cats. Like at the center of an orbiting-particle system where instead of two cats there is an infinite number of this duality of cats that obey the half spin-up & half spin-down rule, (180,360,720-degrees) of an electron or any orbiting-particle. This would mean that in an orbiting-particle system that has an electron orbiting around the center node there is going to be an electron that is not physical at our size & time level but physical at the size & time level that exceeds the speed of light barrier... how crazy it that!

[@sharonminsuk]

OMG, just stumbled across this video - I was not aware of your channel before. I'm sure I'll be back. This was great! Also: I *_never_* buy merch, but if you had Schroedinger's Cat _earrings,_ I probably could not resist.

[@WDWDad]

Aww this is the first time I have seen this video and the cat is no longer available 😭 I hope you bring it back

[@SolstaLynn]

I am here today to tell you that after more than 50 years of beings dead and not dead, that Schrodinger's cat is officially dead. Cat's, as we all know, have a relatively short lifespan, and given that it was repeatedly either exposed to a poisonous gas or not, it still is older than any cat in history. As for Schodinger's human, there is no data on that specific thought experiment.

[@liamclarke64]

Thank goodness for that!!! And, thank you for your comment :-)

[@LenVrijhof]

Not to mention the 8 lives his cat potentially has left after this one.

[@ornessarhithfaeron3576]

Quantum immortality: h e l o 👁️👄👁️

[@CannondaleXC]

Oh wow that was one of the best explanations I've ever heard of quantum mechanics! Fantastic job! I really appreciate the work you guys do.

[@toddhensley880]

Why does the “detector” change the double split result, when the “wall” does not, even though the wall is in effect acting as a form of detector?

[@sogerc1]

Well, if I understand it correctly, it's because the wall interacts with both sides of the wave function but the detector only with the one it measures.

[@arnaldo8681]

because the wall is a different kind of detector. It gives you information about the final position of the electron, but not which slit it passed through, so its effect on the experiment is different it also affects the result. If there was no wall there the electron position would keep going instead of being detected by the wall, it just affects differently

[@armante4u]

The way I understood it is that it has to do with how interaction with the system takes place. A wall is agnostic in its interaction with either a wave or a particle. Whereas a particle detector can only interact with the particle state and therefore forces the system into that state.

[@scabbynack]

Sabine Hossenfelder has an amazing video about Schrödinger's cat. She breaks down more specifics about the interpretation Schrödinger didn't like, and what other interpretations makes the experiment look like.

[@tf9956]

Technically it does. If you check the delayed choice quantum eraser, effectively the board can also be a detector as well.

[@TheMariusDarkwolf]

I actually really love both the concepts of superposition and multiple worlds. At least what I can grasp of them without the math. I've actually read some fiction where they were used as plot points, or background. I've even read a couple series where that was how magic worked in that the "magic users" influenced reality to either pick a universe where a fireball was chucked at someone's face, or they collapsed a wave function so that really rare thing happened instead of the most likely thing.

[@Chris-xo2rq]

The double-slit experiment illustrates two simple things: You can't measure something without changing it and fundamental "particles" is a misnomer, they are not like little contiguous objects. They are wave peaks of the underlying quantum-mechanical field (which also explains the Casimir Effect and virtual particle pair production).

[@PaulSinnema]

You are getting better at this all the time. And damn you are soo smart period. Very well prepared. well thought out, nice animations and very well executed. I really like the way you challenge your team and stimulate them to think out of the box (and me too). Aah, the Cat is sold out. I’ll be checking back. Love to give these to my family. Good choice. Thank you very much Diana.

[@TheTerminator-2]

Schrodinger's Cat is one of the best examples showing why it is a mistake to try to extend math beyond what it has been designed to do.

[@nicholaspescinski7818]

One of my favorite things I learned about was probability. The Boston Museum of Science had an exhibit. Thank you for another great video and lesson!

[@AlisonWondaLand]

Will there be more Schrodinger’s cats added to your merch??? I want one! 😺🙀

[@HuckFinnFantasy]

Bought your shrodingers cat for my daughter and she loved it. It is so adorable.

[@ryandean5941]

This is the best explanation I have ever seen of the concept of superposition and the double slit experiment. Well done!

[@brucecrane9605]

I learned, I was entertained, and I'm a big big fan of Physics Girl. Or Physics Princess. Please get well we miss you.

[@jeffPeck99]

So if I have a shoebox with a dice in it, and I shake the box, and then put it on the ground. If I open it , the wave function collapses and I can see the number it landed on. But if I choose not to open it, the dice stays in superposition at a probability of being any number from 1 to 6. Or the many worlds theory says we split off into 6 different universe's, one where the dice is one, another whete the dice is 2 and so on. Is this correct?

[@slayer8actual]

9:39 "What is really going on here? What is the reality here? What are we actually...what's actually happening? What's physically happening, and the honest truth right now is that we don't know. They physicists have no idea." Nine minutes and thirty-nine seconds ago that is how I felt. And now nothing's changed.

[@billythekid1158]

Good looking, smart and excellent at explaining things. Wow!!! Hope you are feeling good about yourself. People like you make this world a better place.

[@DarthLink1986]

the power of our observation is fascinating and how we interpret those perceptions is even more so to me. I have always loved this experiment.

[@ConversationsWithColby]

I love seeing how truly jazzed up you get exploring and explaining all these complicated wonders of the natural universe! :) :) :)

[@smitisan4984]

What it means is that there's either a dead cat in there with cyanide residue or a very angry cat with a cyanide capsule that could pop any moment. I ain't looking.

[@3DJapan]

I was literally thinking "that cat plush is really cute, I kind of want one".

[@Warm_Summer_Rain]

I like that you brought this up. The cat experiment is always misunderstood.

[@mosienko1983]

00:40 The first time I've seen, in a presentation for the layman, what the point of the whole thing was. Great!

[@jonnym4670]

brings the whole cup half full or empty depending on your perspective to a new level

[@rickjensen2717]

Electrons are not particles or waves - they simply exhibit properties of both. They are just a way of thinking about something we can observe and measure but don't really understand. We also still don't understand what energy actually is.

[@Sturben-qn7ph]

Love the youtube channel name put a lot of creative effort into that one

[@Muuip]

If we consider an electron as a particle surrounded by a wave it explains the wave-interference pattern, and when we detect the electron entering the slit, the detection troubles the wave and only the particle goes through, and we get a particle-interference pattern. Therefore no superposition. Just disturbance of the wave, by the measuring tool, surrounding the electron particle.

[@ZendikarMage42750]

And then there's my inner philosopher going, "But what if we're really all brains in jars?"

[@Hin_Håle]

I LOVE the Schrödinger option! You just never open the box! Kudos to the person who came up with that!

[@Flea_ip]

I love the idea of not knowing which pin you get, and if you never open the box, you don't know. That's just fantastic.

[@JDX123]

Interesting about measuring the electrons,but, ever look at a radio tube under load? The electrons going thru the grids do not exhibit any unusual behavior, they are scattered even though measured.

[@dennise4163]

Put 2 slits next to the tube and please get back to us as soon as possible. My cat's life is literally depending on you.

[@richardcumingsjr3336]

This chick is so cool. I love all the way she explains things in such a happy, enthusiastic way.

[@Insurgent_AF]

Your excitement is contagious. You make me want to return the favor and teach you a few things.

[@NebulaM57]

I have been enjoying a lot of your video recently. I think you do a great job of trying to explain some really tough subjects. But I also wanted to say that I've been getting a big kick out of your little jokes at the end of your videos!! Keep them coming!!

[@StevenYeh]

I recently caught on your channel. Love it! But for now, i just wanted to point out the funny "wave fuction" at 4:27. All the best to you!

[@jebjim9391]

btw, the "Schrödinger’s cat" as merch is the greatest idea of all time -- I'm a man and not really into "stuff animals" and I want one Love your channel btw !!

[@Tjtellsthetruth]

I hope you get better because you are a Force of Nature, your inquisitive authentic charm and thirst for knowledge and ability to explain science in a very easy and relateable way.

[@HalSchirmer]

Late comment, but, great explanation. You should add that " all plushies are autographed* " (*-autographs are on the side that is not being observed)

[@krumplethemal8831]

Schrödinger’s cat means physicists love killing cats but they bypass their guilt by not observing the act, thus the cat can potentially still be alive.

[@Leoric.]

I think the thing that fascinates me the absolute most and something I would love to learn more about, is the collapse of the quantum functions or whatever it’s called itself that suddenly makes a fundamental law of the universe magically just behave differently because we *looked at it.*

[@malk6277]

I love the Pavlov dog/Schrödinger's cat joke at the end!

[@SuperMadman41]

Wow!! Been a long time since i have THIS explanation for the quantum cat. Love it. Thanks for the vid!!!

[@leprifacioncustard4921]

The double-slit experiment gets stranger: if you observe through which slit it goes and then *destroy* that information, the same wave pattern still appears!

[@catrandy7957]

Schrödinger’s cat was named Princess. Princess both loved and hated salmon cat food at the same time, so you never know which it is until after you open the can.

[@ThunderChasers]

Why was I not subscribed lol. Liked and subbed. Been watching for a few months from suggested content.

[@_Woo]

So suspiciously like a video game, there's no need to render unless someone is actually looking at it.

[@christophermahon1851]

Ah, now I understand that I don't understand quantum stuff at all. Thank you. I would really like to see a video on 'wave fuctions', though.They sound interesting.