Quantum Wavefunction | Quantum physics | Physics | Khan Academy
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- Опубліковано 24 чер 2018
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In this video David gives an introductory explanation of what the quantum wavefunction is, how to use it, and where it comes from.
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So far, the clearest explanation I've seen.
Yes yes yes. I totally agree. I don't have any words to describe the quality of his explanation
Amazing explanation
Best explanation
Thank you so much sir
how many words did you speak, before you learned how to speak? Cous, you def. no how 2 speak. Tu 4 ^^^
So true
I agree
It was hard to listen while Schrodinger was staring at us
that means you are thinking!
*Schrödinger
Schrodinger : Ayy, you learning my equation
Lol
💀
My favorite is how he automatically knew what common questions people would have about this. Like, guys this is just the way it is, don't worry about the equation, just accept that psi squared is density probability. period.
'Nah'
- Max Born
😂😂👍
😂😂👍
😂😂👍
😂😂👍
😂😂👍
Me understanding it: oh that’s cool I’m pretty satisfied
Kahn: if I were you I wouldn’t be satisfied
Me: yea Fr I ain’t satisfied at all yet
so I wasn't all alone after all
My exact thought process haha
I've been looking for this explanation for months. Makes much more sense now
He is a legend
So the lecture started with the very question which kept me depressed and from really trying to understand the quantum mechanics...so thank you so much for clearing my doubts.
Schrodinger couldn't interpret the equation, then Max was born.*wave intensifies*
Max was born
Nothing happened actually ehem
*Schrödinger
@@Gavin-cu7ti no one minds being it without the two dots, you don't need to reply that to every comment
@@vers82781) I do mind 2) it's how his name is actually written 3) if it doesn't disturb you, why did you reply to my comment
I find great joy in these physics videos. They help my interests in quantum mechanics grow.
At least he made it clear that we're not the only ones who don't get it
Thanks man!
This is like one of the best videos I've ever seen. Better than my university lecturers. Thank you so much
Schrodinger: so uhhh... yes... I will tell you how I interpenetrate this equatio- do you wanna explain your own way of interpenetrating this?
Max Born: is this a test?
Schrodinger: ............. yep...
*Schrödinger
*interpret
Addressing questions that an amateur like me want to ask and explaining it clearly. Well done!
Thank you soooo much for making it much easier to understand...
Fun fact :- a single electron is present in every possible points within the probability amplitude until it is observed ...
See double slit experiment ...
It’s not actually present, it’s got a single location, we just don’t know where it’s location is so we have a probability of the space the electron could occupy. When it’s observed it then shows it’s single position, but we had no way of calculating where it was until we saw it
man we need this to e linked in a playlist to study it please!!!!
Thank you David!!! This is what I needed ✨💖🙏
I’ve just begun reading a book on quantum physics! Your demonstration about the wave function is clear and sensible ! My take away is that the thing that is waving is the amplitude of probability wave!
Yes. Either the amplitude of the probability wave/magnetic field or of the conversion of matter to energy or energy to matter. Or both. OR, of the motion of the particle/wave moving forward or backward in space/time.
Could it be the motion of the "particle" in the electron field? We know that particles are disturbances in each fundemental particles field, so does this wave mean the motion of this disturbance? The particle can't have a definite position but it can have a definite path/trajectory right? Or have I gotten it wrong? I'd love some insight
@@mozorellastick2583 Definitely it is not about the motion of quantum, but truly on the whereabouts of them, scientists are crazy on matters location and speed! So far we humans failed to pin down quantum , instead, we could only tell how probably them can be, which is their probability. And the value of the probabilities are sort of waving along ! Interesting!
Very Clear & nicely explained, Thank U Sir.
Thanks ! what a neat and understandable explaination.
I feel this is an iconic explaination
Best explanation I've ever had!
Wow that is amazing proffesor Dave... it's true you understand concepts in minutes of which have been taught for a couple of hours in lectures in vain of understanding
He's the same guy in "prof. Dave explains" vids?
I liked the bad news you said in the last two minutes... It made more interested to know more about the quantum mechanics
Thank you so much this help a lot
Very good minutes of quantum wave function.
Jesus what a well made, well explained video. I am truly fascinated by this topic.
Thanks .. indeed the best video I have got to watch
A greattttttttt teacher, No words... Speechless .....thank you veryyyyyyy much.... 😘
Very elegant explanation.
😎
I really understand this now. Thanks sir. I'm ahead of the class now.
Thank you from the bottom of my heart
Good explanation, thanks!
Thank you 👍
In the Expanding Graviton model, gravitons are (1) the carriers of the physics constants AND (2) gravitons are what wave functions are describing. Therefore, what is waving is/are the carriers of the physics constants.
Thank you!
That was a great explanation.
Woa, very well explained 😁🌱
This was and excellent explanation of Schrodinger's equation. Very good speaker and a clear explanation. Wished he could have addressed what are the dimensions or units of "x".
In the 1-dimensional case, x is distance, with dimension m (meter); in the 3-dim. m^3. For psi it is m^(-1) and m^(-3), since probability itself is a pure number with no unit.
Very well explained sir
Hey Khan academy. I had a thought. Maybe you can say yay or nay to it. If the wave function can happen with particles and atoms (with mass), could this account for all the extra mass they calculated needs to be in the universe? If electrons and atoms are reacting (interfering) with all their other possible realities, then is it possible that their mass is duplicated, if only temporarily? It's hard to imagine that a probability of something would be real enough to have mass, but on the other hand, it's definitely real enough to interfere with itself and all its probable twin buddies, so why not? Thanks
To bring you up to speed on dark matter (The universe's missing mass) it is not that we don't know what causes it, the problem is only that we can't get a good look at it, as it seems that it doesn't interact with the electromagnetic spectrum (Our most versatile and common source of information in astronomy). We know that it is a different thing than matter because you have effects such as gravitational lensing (Google it if you are unaware) which can occur regardless of dark matter's proximity to other matter. Besides all this, probability density is not equal to real density. Wavefunctions do not increase the mass of a particle, a great proof being how accurate Einstein's General Relativity is without his knowledge of quantum physics. In fact, Einstein famously hated wave functions and the unknowability inherent to quantum mechanics. To conclude, nay.
Thank you! Quantum mechanics are beautiful.
Jesus Christ it's Max Born
Lol
you have been so helpfull
Best description of the present state of the “understanding” about wave-particle duality, or non-understanding depending on your position on the interpretation question.
There is no such thing as wave-particle duality. There are only people who don't understand physics. In this case it's high school physics. :-)
Very well explained.
This is the best explanation of wave function in UA-cam. But we don't find such clear explanation on every topic that we come across, so can you refer a book on QM which we should follow to be conceptually clear?
That's cool. especially since this explanation is wrong. ;-)
Nice video! I do have a question though. Assuming a complex wavefunction, how are we graphing the wavefunction on a linear axis (rather than the complex plane)?
Thank u😍🤗🤗🤗🤗
you.....are.......awesome.
tysm
This is actual proof for why you should learn the subject before memorizing the formulas
What application are you using for
making your videos
I lapsed for a moment at 9:22, when I looked back that x! really confused me :D
😇 Say thanks to you for the interesting video, it certainly is greatly appreciated and I really value your hard work !👍
Connect to Soul the glory for hard work should be given to G-d that gave physicists like Schrödinger ideas
The same thing comes up with a deck of cards. When a deck is being shuffled everything is a probability but once a card is pulled the probabilities collapse to be 100% chance of that card being the one pulled.
Because the past is set in stone. The future is undetermined.
I think the electron is shrinking and expanding at the same time giving the wave and particle probability and once measured because of the size we see a sliver of the wave or ie particle. Which gives it’s a superposition moving through the curve of space
It is easy to understand psi. I fully understand it like when I learned how to eat an orange.
Finally someone tells it like it is
Very helpful
Excellent👍👍
Does the quantum wave function give you energy levels (amplitudes) and how often (frequency) of energy level in the future?
I understand what you are saying about the probability of psi squared. I thought the act of measuring an electron changed the momentum? Won't that change the electron? Are you talking about numerous electrons with the same wave function? Is this like firing photons at a double slit?
Great video, thankyou.
Thanx
Psi (Ψ) - in the light of quantum behavior.
The Problem with Quantum Measurements - Psi (Ψ)
The '' measurement problem'' / ''wave-particle collapse''
About one wave measurement of one quantum particle.
#
There isn't electric wave without quantum particle.
The wave-function is result of a real work of quantum particle (h)
The wave-function Psi (Ψ) is derivate form of quantum particle.
The wave-particle collapse problem could be contemplated as
boundary changes of wave and particle simultaneously.
#
When the wave collapses, the pure electric particle (E=h*f)
changes its parameters into negative potential state - Dirac's
virtual / antiparticles (-E=Mc^2) and "disappears " in Zero Vacuum T=0K.
=====
Great video! The Everettian Multiverse explanation of the wave function seems to be the *only* explanation that is actually an explanation - and its an explanation with deep and testable implications for understanding our universe and information theory. The instrumental philosophy of 'shut up and calculate' is simply bad philosophy - it blocks progress.
Cool, except that when you read Everett's thesis (which you clearly didn't), then you will find that he made a major mistake in his second sentence from which he never recovered. ;-)
What do we mean by "finding the electron"? We detect something that looks like a dot but what is it? We've grown accustomed by analogies (bad analogies) to think of particles as tiny balls or even dots ("point particle") but particle itself only means "small part" (Lat. particula) what can be actually anything: a "ball" or a "string" or a "spring" or whatever else. My (probably shallow) take is that it is some sort of vibration of spacetime itself and what we experience as "dot" is an effect of it, not it, that the particle is a vibration of spacetime itself or maybe a "pressure density" but something of spacetime as "substance".
The election isn’t a point particle. It’s an electron field. We don’t think of the magnetic field as point particles.
@@timrodriguez9532 - The "election"? That's a funny Freudian slip! ;p
@@timrodriguez9532 - A lot of people, including physicists present it as point particle. Famously Feyman claimed that in one of his much referenced lectures.
I agree with you but there is this contradiction of concepts that physics, notably quantum mechanics, has been dragging on since the "particle-wave" duality was established (by Einstein in 1905 if I'm correct). My point was (I believe because seven months have passed since then) just to emphasize that "particle" only means "small part" (literally) and that the nature of such "small part" is sometimes confusing.
Beautiful mathematics
When the quantum wave function is measured, the energy level at the present moment in time is given?
Through superpositioning correct?
Thank you
thank you need expansive review had it 40 years ago at 4.o atrified
there is a mistake in the schrodingers equation u wrote...on left side it should be reduced plancks constant s square but its not in there
Wave functions are shown as that trident or is otnshown as something else
So, to my understanding, wave function in QM is used analogous to x or position in classical mechanics? Due to uncertainty principle small particles cannot have the exact known position (some discrete value x) as opposed to large, everyday object. Therefore, we have to use the whole function in the QM equations that involve position, as it has no discrete value. Can anyone tell me if my understanding of the wave function in terms of Schrodinger equation is right?
the way he explains, even secondary school students can understand it, compared to my physics lecturer at university.
That's the problem... he tells you a bunch of baloney. Yes, you can understand it, but you are walking away with the wrong mental model. This is not how it works.
I always thought that what was "waving" was a magnetic field. As the particle collapses its mass becomes a magnetic field. Then as the field collapses its energy becomes matter. So on and so forth. Each time this happens the electron "moves" backward or forward through space-time. Each time "searching" for the path of least resistance. That path being affected by the other fields around it. I thought Feynman wrote about that in one of his books.
I will do it
And in which playlist is this video???
Beautiful
Tysm 😭
Devide by" space "is the thing that is moving.
Nice explanation! Many thanks! First I found I could understand! Regarding probability of finding a particle: - exactly WHERE? In the atom? In the LHC? In a specific point in time and space? Or any of these alternatives? Weird.....seems more a way to circumvent lack of more specific math or even worse - lack of deeper understanding of particle physycs - for the subatomic world. Could it be that all these Nobel Prizes fooled us for so many decades? I suppose it is necessary to work this out or Science will resemble more a religion.
In fact I heard Sean Carroll talking about this fundamental problem without having a minimal rational of the wave function, but now, after this video, I suppose I am starting to understand the message he was trying to pass through.
Hey the wave function gives you the probability of finding an electron at a particular time and point in your QUantum state.
What exactly is a quantum state?
basically the tiny particle system you're studying
The wave function probably helps in giving you the probability of finding an electron in a p sub shell or an s-shell.
Hope this helps! :)
You have a mistake!!!
In the schrödinger equation, at the left side you wrote, it is supposed to be ĥ² (h-bar squared )...
I guess we can forgive him for what hes doing for all of us
Knurdddd
God bless Khan Academy
Wow😲😲😲
so cool
@08:00 you will never answer these questions UNTIL you analyse where dBroglie wave equation comes from (lambda = h cross/p)
This opens up one electron universe theory lol
Wasnt this explained by Quantum Field Theory? That basically electrons are projections of many layers of quantum fields, so I would assume the Shrodinger Equation gives you the wave function of a particular wave in space, which at the quantum level is waving like the ocean.
I thought the wave function is complex and you have to square it before getting the probability function which is like a Bell curve?
What exactly is the X- axis in this concept? you said its the region But is it measured in a unit like cm, mm etc? And in the double slit experiment you shoot electrons at a wall or a screen and then look where they land. if you just do this with no split would you get the wave funktion?
So if the charge density is the wrong interpretation then the magnitude of the wave is not correlated to the charge when you measure it? That would be the case if it's only correlated to probability of position. In other words for that to be correct it tells us nothing about the charge extent when we measure it? I'm asking cos ive not personally seen experiments like this.
Lets say we have found the x value where an electron is most likely to be. What does this help us with? Where could you go from there?
Dudes be like: "wave check"
*Shrödingers equation intensifies*
what can make up probability(s)? is there greater probability of a particle because there is more energy at location, or something else? does a particle form when there is enough energy?
Nice
isnt the schrodinger's equation h cut squared over 2m ?
Hello everyone, I would like to ask a question.
How do you proceed, in a typical experiment, to confirm whether the wave function has collapsed or not?
Let me explain. Let's take an overlapping electron of states and let it pass through a "channel"; I want to know if it has remained consistent up to a certain point.
But doesn't the act of checking coherence cause us to lose it?
In a nutshell, how do we verify collapse if the act of measurement itself causes it?
Thank you
@Ensrick thanks
have a doubt sir. In wave propagation water or sound , how individual particle vibrations are transmitted from particle to particle in the direction of wave propagation? There are gaps between particles in solids, liquids and gases. Is this not against principle of locality?