Particle in a Box Part 2: Interpreting the Results

[@noise_]

I started quantum mechanics on a masters with no real background. These videos gave me so much insight, a week ago i literally barely understood what a couple of symbols meant. Now i can see all the documentation and understand everything on them. For this i can’t thank professor dave enough. Now i need all the exercises to know how to tackle them!

[@zeyadahmed731]

May I know in which field is your Master?

[@Andy_M.S.c]

@@zeyadahmed731 i guess you may not

[@stringbean02]

I hope maybe you'll see this at some point. I'm currently in my last semester of my chemistry degree and have a research presentation coming up that will determine whether I graduate or not. My research involves synthesizing quantum dots and I was struggling to connect how the particle in a box model determines the wavelength the QDs absorb at. I could understand the model and I know that particle size determines the wavelength, but for the life of me I couldn't make them connect with the proper equations. These two videos have finally put it all together for me and I couldn't be more grateful as I have a meeting with my professor in 10 hours. Now I won't look stupid for not being able to connect the fundamental concepts the entirety of my research is based on. An absolute blessing at 2:00 in the morning.

[@casperryde9602]

Very impressive how you can explain such difficult matter in such an easy way and using this ability to reach many people. Respect !👏👏👏

[@RengodStablord]

This saved my butt today! Thank you so much for putting together such thorough content. I hope you are happy and healthy during these hard times.

[@guillermogini6879]

3:37 in the morning here...I have a quantum mechanics test today and I wish I'd found professor Dave's videos before. Thank you professor Dave! greetings from Moscow

[@glennpearson9348]

Quantum mathematics made easy to understand. Also, recalling all those trigonometric identities was a fun trip down memory lane for me. Good stuff, Professor Dave! Oh, and it was nice to see a slightly different side of you on Catz's channel the other day. Take care and be safe.

[@che-maticschemistrymathema7044]

I'm so happy to have a teacher like you who knows everything 😍😍😍😍😍😍😍😍😍😍😍😍😍😍, Physics, Chemistry, Biology, Astronomy................💞💞😍😍

[@cguy96]

Oh, he doesn't know _everything._ But he darn well makes sure he knows what he is talking about before he posts!

[@che-maticschemistrymathema7044]

@@cguy96 😍😍But I see he knows almost everything.

[@vikasyadav495]

Great Video. Awaiting other complex situations - Finite well, Harmonic oscillator, etc.

[@bigbrothersinnerparty297]

I think it would be better to upload hard concepts like these in a row as I have to rewatch most of these videos every time since I usually forget some of what I had learned before lol. Thanks for the great videos!

[@0cgw]

Great video. Another way to see that =0 is to use the symmetry x maps to a-x which preserves the system. This would send to -. But since it is the same system, we get = - so that =0. Also, =E since =0 as V is either zero or the wavefunction is.

[@criskity]

Imagine flat earthers trying to understand this. They'd just balk and say "Math isn't real!!"

[@northernskies86]

@@EdwardHowton If you're interested in learning this high-level physics and you don't have the mathematical toolbox to understand it, I highly recommend you check out Professor dave's series on math, starting from basic, elementary school math all the way up to vector calculus and linear algebra, and everything in between. But flat earthers are allergic to learning and deny everything their puny minds can't comprehend, like calculus or physics.

[@frede1905]

@@EdwardHowton This is nothing compared to modern physics today. It takes a lot of time and dedication to just scratch the surface of the mathematics of modern physical theories, because it's just so insanely complicated. Even general relativity is practically nothing compared to that, and it is famous for being hard to understand. It takes years and years of hard work to reach the level of mathematical literacy that these physicists have. That is why I have huge respect for those who are able to participate in developing these theories.

[@frede1905]

@@EdwardHowton Yes, I agree. I am more of a physics guy, and I know that I am gonna study physics after high school. Because I am so interested in it, I learn as much as possible that my brain can understand, and just this summer I tried to learn as much QM as possible. Now, something I've learned from this experience and just learning physics/mathematics in general is that everything is much easier to understand and much less intimidating once you get used to it. I mean, when you look at something, especially mathematics, for the first time, it looks extremely complicated and intimidating, but once you unpack the symbols and you start getting used to it, you realize that it's not as hard as you first think. When you read my last comment, it probably felt like these physicists are superhuman or something, but I think (and hope) that everyone can reach that level if they really want to, and if they are dedicated enough. Although the mathematics used in the most recent theories are indeed insanely complicated, I think anyone could eventually understand it if they had the dedication and time, for the reasons above. Now, that being said, I completely agree that it's insane how people can fall for something like flat earth. It doesn't even require science or math to debunk it, although it's much easier to see the insanity of their arguments if you know some basis physics. That gravity isn't real, or that water can't curve is by far the craziest of their arguments.

[@thephantomeagle2]

It's perfect for flat earthers since they're ZEROS.

[@Diaming787]

Saying math isn't real means they aren't real themselves. They are made of quantum particles too, requiring such level of math.

[@constancafigueiredo106]

Thank you so much for your videos on Quantum Mechanics. It's so easy to understand when you explain it like that

[@ManojKumar-cj7oj]

Please,Dave ! Add some more videos in this brilliant series

[@paulg444]

His first part was great, but this is where he really delivers !

[@IslandHermit]

I'd always heard that quantum calculations were "difficult". After seeing this example I realize that most of the math itself is not difficult but rather the sheer amount of it required for even the simplest of problems.

[@hidetsuguhiraki2008]

Your video series are always easy to understand. In physics, we must understand what equations mean in the real world. Your video series' detailed explanation is beneficial for my study of physics. Thank you very much, Sir.

[@KrasaGalyaShararam]

Your videos on infinite potential box are superior! They helped me a lot. Thank you so much

[@eggieeeeeee]

Hi professor Dave,can you please upload videos in this series (modern physics),a little quicker, as I wait eagerly for these tutorials? Love you and all your tutorials.This is just my request. Stay happy. 🤗❤

[@ProfessorDaveExplains]

these are hard to make! i do them as quickly as i can. just revisit them all in a row in a few months to cement the information.

[@eggieeeeeee]

@@ProfessorDaveExplains Okay,thank you!😀

[@ava_niche]

@@ProfessorDaveExplains Really appreciate the work you're doing

[@jesusdavidrinconpuche2193]

I've seen this problem since 2015 and I still think it's really interesting

[@Релёкс84]

16:30 perhaps an easier way to explain it is that the particle is constrained in a finite space so its average velocity (and thus momentum) has to be zero, and yet as we saw earlier it cannot have no energy so it has to be wobbling aroun, giving it a non zero average kinetic energy.

[@coreyanderson3288]

Also since kinetic energy is always positive (velocity squared) it cannot be equal to 0 if there is motion (regardless of moving in the +ve or -ve direction)

[@SADI1997]

That was just Awesssoooommmmeeeeeee. Thanks a lot.....expecting more lectures

[@지구과학천문학]

Best Video Ever

[@menglongyouk167]

Thank you for putting efforts into these. Appreciate it.

[@tamojitmandal5382]

It's really beneficial for me to understand the concept of box normalization ,, again thank u

[@MrShovelBottom]

15:15 gonna pause here to see if my ans is right. But my assumption is that p = 0 because p is time dependent whereas energy is not. And we are dealing with a Time independent schrodinger equation Edit: NVM BRO

[@michaelmurphy8736]

At 16:26 why wouldn’t -psi right just be equal to psi left as typically a negative of a vector is just in the opposite direction?

[@epicchocolate1866]

These aren’t vectors, they’re wave functions, this is representing a standing wave (look up wave on a string), which is a left travelling wave and right travelling wave, these two values are not equal everywhere.

[@ManojKumar-cj7oj]

Hey Dave please make one more video on this series on PARTICLE IN A RING 🤩

[@arkaeminem]

Nice explanation... Could you make a video on harmonic oscillator by schrödinger's equation

[@ProfessorDaveExplains]

yep that one is coming

[@sanjayvasnani988]

@@ProfessorDaveExplains Are you still working on it? I would love it if you could continue on this series. Your videos help me understand complicated stuff easier.

[@ProfessorDaveExplains]

Yes sorry! I have two more almost ready to produce and then there will be at least four more after that.

[@sanjayvasnani988]

@@ProfessorDaveExplains Wow, Thanks for replying.

[@nasikhossain2721]

Seeing ur video I am big fan of ur From India

[@cliffordwilliams9597]

@16:11 => 16:37 Mind Blown

[@amiraro6345]

Thank you very much ❤️😊💕💖💖

[@aymenbk9138]

thank you so much for this

[@Liltommy-bz8ky]

Thanks You just saved my life

[@pearlsequeira3989]

😃your really good at explaining this👍 now i totally get it

[@cliffordwilliams9597]

Thank you Professor Dave !!!

[@ilper1625]

Hi Professor. You say v can not be 0 for there is no particle. But a particle can travel exactly perpendicular to x and v(y) = v=const and then v(x)=0. Of course one has a 2d problem then, but does this change things and why? Can part of v(y) go to v(x) and why if there is not an interaction with the walls?

[@yasminsedra7455]

this is super useful! Thank you so much

[@eswarsai8293]

nice explanation loved it whole

[@FrostDirt]

Have you applied for verification? It looks really weird seeing a channel this big without the mark.

[@ProfessorDaveExplains]

hmm i hadn't really considered it, i'll ask my partner manager

[@schifoso]

Brilliant!

[@scientist1905]

Best explanation

[@tadeletekeba13]

Thank you so much prof Dave (Tadele__Ethiopia)

[@rohanthakrar7599]

Where is the video on Bra-ket notation ?

[@ProfessorDaveExplains]

a few videos back in the modern physics playlist, either the one on operators or the one after

[@rohanthakrar7599]

Professor Dave Explains Thanks

[@ahmetg.7145]

Have to work on the equations to memorize them. 🤩

[@sanshou2]

Why is the last video in playlist private?

[@ProfessorDaveExplains]

I will release it soon! And more after that.

[@Pheosis]

@@ProfessorDaveExplains Wow, maybe it will simultaneous with my uni lectures :)

[@amiraro6345]

Thanks from ALX_EGYPT

[@rowangoebel-bain3447]

super helpful!!

[@chriswinchell1570]

If quantum tunneling explains radioactive decay then why doesn’t it occur in every nucleus? What is different about unstable nuclei?

[@ProfessorDaveExplains]

Check out my tutorial on nuclear reactions. Proton/neutron ratio is off, nucleus too large, etc.

[@chriswinchell1570]

@@ProfessorDaveExplains Thanks.

[@chriswinchell1570]

@@ProfessorDaveExplains So, is it safe to say that tunneling and hence transmutation of elements is just much more likely when the nucleus is large or the ratio of protons to neutrons is unfavorable? In other words, is it that the potential to overcome is much lower than in a stable element? I.e, in theory tunneling can still occur in stable elements but the half life is very large? BTW, can half lives be calculated knowing the atomic mass number and atomic number?

[@ProfessorDaveExplains]

I don't really know of any connection between quantum tunneling and nuclear decay. But yes, those are the reasons a nuclide would decay. Half lives aren't calculated, they're measured empirically.

[@malehasharifi8304]

Hello professor thanks for your fantastic teaching I am an ESL student but I really like to be a nurse 👩‍⚕️ and work in a medical field please help me in this way give me some advice my writing is not good I hope you know what I am saying thanks 🙏

[@hiesenbergw.w555]

Hi Doc please help me I can't play your next videos Why is that?

[@ProfessorDaveExplains]

Releasing them soon!

[@fantomphalcon9153]

“Imaginary terms” - flat earthers’ would love that, if the definition made sense to them “Yeah, complex numbers dude, J notation, -1 -using an imaginary number to solve an equation that breaks the x, y axis, y’know, complex shit” - shit, aliens have landed, but how did they get through the firmament? - We need a model........ I understood and this ‘imaginary number shit’ made it all a bad dream of quantum reality, or some shit??!

[@carultch]

Pretty much. It's a name given by a critic of the concept of imaginary numbers, that leads people to believe these numbers lack any real world application.

[@samh5550]

Hey professor, would you please share with us how do you plan and make your videos and what are the equipment and software you use? you inspired a lot to think seriously to start a valuable content in our specialty field, and your advise will be very helpful. Thank you very much!

[@ProfessorDaveExplains]

i use adobe after effects, it's the best! very easy to use

[@samh5550]

@@ProfessorDaveExplains What about the camera and microphone professor?

[@ProfessorDaveExplains]

for these ones no camera, just audio. i use a crappy mic i got a radio shack for like 40 bucks forever ago, sounds surprisingly decent

[@ianlee5812]

Can't the dilemma that a particle can have nonzero energy and zero momentum be explained by Einstein's mass-energy equivalence? Since mass is proportional to energy, a particle of a finite mass will always possess some energy, regardless of its velocity and momentum?

[@AnimeForeLife]

Yeah I'm gonna need about 3 or 4 levels of math that I dont have to follow this. I heard of the wave function, but I have no idea what the heck you're doing with it

[@ProfessorDaveExplains]

Well this is a bit of a miniseries so start at the one on operators in quantum mechanics in my modern physics playlist to get more context. But for the math that's eluding you, visit my mathematics playlist and head towards the bottom, all the linear algebra and calculus is there for you!

[@yufan]

Can n be negative？

[@cafe-tomate]

If n is negative you get -sin then it's just the same but multiplied by the scalar (-1) And as we know the physics don't change when the wavefunction is multiplied by a scalar So considering the negative n cases is redundant (it's considering twice the same wave functions) Therefore we stick with the positive values of n Hope this helps

[@carultch]

@@cafe-tomate Θανκ ιου.

[@majdiabdalla3505]

Thanks

[@simangcheung9420]

大変助かりました、ありがとうございます

[@alaabdessayed329]

It hits different when u are not learning this for fun,but cz u have a national exam on it 💀

[@sabbitiswarender7026]

Professor tell about life on mars

[@medicalbiochemistry_]

👍👍👍

[@SampleroftheMultiverse]

I have energy therefore I exist.

[@gabitheancient7664]

so that's why absolute zero temperature is impossible? because a particle can't have 0 energy?

[@cafe-tomate]

I think energy can be less than zero, if the potential goes below zero

[@wertiadreams7949]

this is pretty easy to understand and I'm generally stupid

[@freshely9309]

Wow the quantum world really is bizarre

[@utkarshraj3272]

👏

[@briefinsight4486]

Heart this Comment Dave or you cant do that?