It would have been very difficult to jump start my my self learning QM using Griffith's book if had not found your videos. Thanks for making these videos.This was just what I needed.
A lot of physics books have an irritating tendency to go on forever about a million different things at the same time, so that it takes a very long time to read them. Video tutorials tend to be much more straightforward and to the point.
You are excellent at explaining your mathematical reasoning. Your mini visual proof of e ^-ix multiplied with it's complex conjugate was very helpful. thanks
No real magic there... 1/i is equal to -i. You can see that starting with i^2 = -1. Dividing both sides by i should give you i = -1/i, so multiplying both sides by -1 gives you -i = 1/i. It's handy sometimes to move i to the numerator, so I've made that 1/i --> -i conversion.
It's worse than that, actually -- Psi(x) can be positive or negative, and can even by complex. The missing piece is that Psi (the wavefunction) is not itself the probability density. Instead, we treat |Psi(x)|^2, the squared absolute magnitude of Psi(x), as the probability density, and |Psi(x)|^2 is always a positive real number.
I took QMI last semester and aced it. I had no idea what any of the math meant, but thanks to you know I understand what this means!! only took me 2 weeks into QMII to realize I didn't know what I was doing
If the wave function satisfies the conditions for normalisation does it suffice to differentiate the integral of psi squared dx = 1 wrt time? And then the RHS goes to 0?
At around 13:30 You divide the Schrödinger equation by ih, and the way I would have computed that, the i would have stayed next to (2m), however you have placed it as if you were multiplying the equation by i. I also am unsure of what happened to the negative symbol in that step. Could you please explain the reasoning behind these steps?
This is my mom’s account but I think he multiplied by i on both side. On the left side of the shrodinger eqn you would have i^2 = -1 and hence the signs are flipped.
I can't get the part when you bring up functions in 02:37 how can probability be negative? sigh represents probability of finding a particle in some point of x right? well how can it be negative?
at 19:08 the reason it is true that because differentiation is a linear transformation hence superposition and homogeneity is preserved, for people who wonders as to why he was able to rewrite the expression
dear,i m confused here,once you said that infinite square amplitudes are not normalizablet,right,as in dirac delta function,/////then you fit this idea to integral(summation) of infinite basis. as we know that square integrable functions converges in hilbert space in h2 space,i.e in infinite basis. so normalizable.
Hi I am having trouble understanding what you said at 5:35 that it is not posible to have a function that stays non zero or goes to infinity as x goes to infinity and still have to be integrable. If you could explain that will be great thanks.
I think i understand: The wave function has to be zeros at both ends -infinity and pos infinity because if its not the the integral from -infinity to infinity will not be 1 thefore the wave function is non-normalizable.
I was asking myself the same question - mathematically yes, but would it make sense for a wave function having a negative sign? I think so, yes, but I could be wrong...
The wave function has a real and an imaginary part. Both of those parts are a wave which oscillate between positive and negative. If you multiply the wave function by -1 you just change the phase of the wave by 180 degrees (pi radians). @@niemandwirklich
If the constant is (for example) -3.5, then positive 3.5 would work just as well. The sign of the constant doesn't make a difference, because we're interested only in the square of the absolute value.
It would have been very difficult to jump start my my self learning QM using Griffith's book if had not found your videos. Thanks for making these videos.This was just what I needed.
What a coincidence, I also came here because of Griffith
and same here
A lot of physics books have an irritating tendency to go on forever about a million different things at the same time, so that it takes a very long time to read them.
Video tutorials tend to be much more straightforward and to the point.
Best explanation of wave function normalization on RUclips.
An Excellent exposition of Griffth's much abbreviated proof in chapter 1 of the 2nd ed.
You are excellent at explaining your mathematical reasoning. Your mini visual proof of e
^-ix multiplied with it's complex conjugate was very helpful. thanks
No real magic there... 1/i is equal to -i. You can see that starting with i^2 = -1. Dividing both sides by i should give you i = -1/i, so multiplying both sides by -1 gives you -i = 1/i. It's handy sometimes to move i to the numerator, so I've made that 1/i --> -i conversion.
It's worse than that, actually -- Psi(x) can be positive or negative, and can even by complex. The missing piece is that Psi (the wavefunction) is not itself the probability density. Instead, we treat |Psi(x)|^2, the squared absolute magnitude of Psi(x), as the probability density, and |Psi(x)|^2 is always a positive real number.
hey, could you explain why we can factorize with a derivative ? I am about the question left unanswered in the video
soo much thanks mahn, been searching for this for years
at 14:34 it should be PSI* (psi star) :)
I took QMI last semester and aced it. I had no idea what any of the math meant, but thanks to you know I understand what this means!! only took me 2 weeks into QMII to realize I didn't know what I was doing
@Brant Carlson Could you please expand on the @18:48
great explanation of probabilistic interpretation! I finally understood the relationship thanks.!
would love a video on expectation values and spherical polar coordinates
Great explanation! Much appreciated before my exam!
this will greatly help in my today's exam.... superb!!!!
What software are you using?
Great lecture. Thank you!
thanks, clear and concise!
Fantastic series! Thanks a lot for sharing
dear sir there is a slight mistake in the 1st term of schrodinger equation on the RHS at 6:24
Great video sir.. thank you :D
Thank billion time for this amazing video , go ahead for such amazing explanations👍🏻😩😩😩
Didn't know Eric Foreman taught quantum mechanics.
Haha
14:48 There is a star missing on the last blue psi
for those who are confused :)
Excellent lecture...thank you.
This is golden. Thanks alot!
Brilliant!
sounds like main guy from that 70s show
At 23:08 why did you not integrate from negative infinity to positive one but negative one to positive one?
the epsi is zero at any intervak except this
If the wave function satisfies the conditions for normalisation does it suffice to differentiate the integral of psi squared dx = 1 wrt time? And then the RHS goes to 0?
great video.
At around 13:30 You divide the Schrödinger equation by ih, and the way I would have computed that, the i would have stayed next to (2m), however you have placed it as if you were multiplying the equation by i. I also am unsure of what happened to the negative symbol in that step. Could you please explain the reasoning behind these steps?
This is my mom’s account but I think he multiplied by i on both side. On the left side of the shrodinger eqn you would have i^2 = -1 and hence the signs are flipped.
What calculus you talked when you solved the integral?
I'm pretty sure that the normalization constant at the end could also have been MINUS the square root of 15/16.
I can't get the part when you bring up functions in 02:37 how can probability be negative? sigh represents probability of finding a particle in some point of x right? well how can it be negative?
That's probability density psi(x)
Not probability psi(x)2
thank u sir...
at 19:08 the reason it is true that because differentiation is a linear transformation hence superposition and homogeneity is preserved, for people who wonders as to why he was able to rewrite the expression
explain more is this not simple common
The reason isn't this complex
thank you so much prof. carlson. i learned a lot from your lecture videos. do you have lec videos on many particle physics or quantum field? thanks :)
dear,i m confused here,once you said that infinite square amplitudes are not normalizablet,right,as in dirac delta function,/////then you fit this idea to integral(summation) of infinite basis.
as we know that square integrable functions converges in hilbert space in h2 space,i.e in infinite basis. so normalizable.
Hi I am having trouble understanding what you said at 5:35 that it is not posible to have a function that stays non zero or goes to infinity as x goes to infinity and still have to be integrable. If you could explain that will be great thanks.
I think i understand: The wave function has to be zeros at both ends -infinity and pos infinity because if its not the the integral from -infinity to infinity will not be 1 thefore the wave function is non-normalizable.
Position density
I dont know who the first person was to put arrows on graphs but that person deserves some sort of punishment
hi, can the constant be a negative value
I was asking myself the same question - mathematically yes, but would it make sense for a wave function having a negative sign? I think so, yes, but I could be wrong...
The wave function has a real and an imaginary part. Both of those parts are a wave which oscillate between positive and negative. If you multiply the wave function by -1 you just change the phase of the wave by 180 degrees (pi radians).
@@niemandwirklich
If the constant is (for example) -3.5, then positive 3.5 would work just as well. The sign of the constant doesn't make a difference, because we're interested only in the square of the absolute value.
explain ???//
Brant Carlson,
May I know why 18:48 is true?
late but just take the derivative using product rule, some of the terms cancel out leaving you with the equation Brant left
@@RaveSlave2DaGrave Can you be more specific please?
@@RaveSlave2DaGrave thanks!!
can anyone show the step for 22:00?
That is the most simple way of expressing it. u cant get anything more simpler. Its just like x^2=x(x) or u can say x^2+x^2=x(x+x)
@@cellerism pls help is it just that he took partial dx common or something big i missed
3:44 am and 6 hours till ny final
wrt the derivative of the partial derivative of psi*, why isnt +(iV/h-bar)psi not psi star?
1st derivative****
Yeah he forgot
d'fuck??