To try everything Brilliant has to offer-free-for a full 30 days, visit brilliant.org/FloatHeadPhysics . You’ll also get 20% off an annual premium subscription. Also FAQ 1) What does it mean to add two waves together? I could have been clearer here. The bottom line is since a wave packet can be mathematically constructed by adding lots of pure sine waves of different wavelengths (Fourier series), a wave packet contains multiple wavelengths. So, an electron can be thought of as a wave packet HAVING multiple wavelengths, and hence HAVING multiple momenta. 2) What's the intuition behind energy time uncertainty? If you hear a tone for a small time, you are unsure about it's frequency. (You don't know if it's a pure sine wave or not). This means you are unsure about it's energy (E = hf). But since the time interval was very small, you are pretty accurate the absolute time value when you made the measurement. On the other hand if you hear a tone for a long time, you become more sure about it's frequency. (You have much better idea about the repeating pattern). This means you are more sure about it's energy. But since the time interval was large, your accuracy about the absolute time when you made the measurement went down!
I love how every time you make a video like this you talk as if you brought the scientists back from the dead and had lunch with them to make this video.
Yeah at first I found it patronising, but then I realised it is the perfect way to explain things. The conversation is the stepping stones to understanding 👌
Haha, when you read well written books, that's exactly what it feels like. I kid you not! (Try the book, 'surely you are joking mr. Feynman'. It's so nicely written, you feel like Feynman is sitting next to you explaining his life)
@@Mahesh_Shenoy"Curiosity is the spark that ignites the flame of discovery. Embrace your curiosity, ask questions, seek answers, and never stop wondering about the world around you. For in the pursuit of knowledge, you shall find the secrets of the universe, and the universe shall reveal its secrets to you." Remember, science is a journey, not a destination. It's a mindset, a way of thinking, and a passion for understanding the world. As a scientist, you'll encounter challenges, failures, and setbacks, but also moments of triumph, wonder, and awe. So, cultivate your curiosity, stay curious, and never lose your sense of wonder. The world needs more curious minds like yours, eager to explore, discover, and push the boundaries of human knowledge. Now, go ahead, ask a question, design an experiment, collect data, analyze results, and draw conclusions. The scientific method is your tool, and the universe is your playground. Happy exploring!
Almost 20 years ago, I first came across the uncertainty principle in Class XI Chemistry studying the atomic structure. This is the best explanation yet. Indeed intuitive. And over the years, I've realised that it's not that some subjects and some topics are tough, it is the quality of books and quality of the teachers that make a difference!! And if you're not in luck with the teacher's quality, do get good quality books!!
This is how I feel too! To have a teacher or a book that makes a subject feel easy is a blessing. And it makes you wonder if some subjects aren't intrinsically harder, but are rather just taught poorly.
This is genuinely the best science education channel out there man. Have never left any of your videos without having learned something new or in a better way than I previously understood it.
He explained it well. Actually, the formula actually applies to all waves. You would just use the frequency instead of the momentum for non-quantum objects.
But be careful Quantum Physics is FICTION. Like many other pseudo-sciences. Like faster than light travel, time travel to the past, and other dimensional universes. Those quack do like he did he explains something true and then switches to his pseudo-science
A sign of a smart person is being able to recognize that they do not understand something. You would be startled by the percentage of people who accept concepts that they misjudged to have understood.
Same for me. I find the quantum world very strange and confusing, even more the more I learn about it. I'm trying to get accustomed to these explanations but have still a long way to go. I always wonder how these quantum effects add up to the predictable, deterministic macroscopic world we live in!
@@Mahesh_ShenoyHi! Could you please explain the physical meaning of adding another wave to the electron wave (I mean does it mean shooting another electron to the original electron)
@@Grecks75 If you understand geometric wave optics with its wave interference and superposition, you can understand quantum mechanics quite "intuitively" (intuition is a form of education and according to Albert Einstein, education is the layer of prejudices laid down upon oneself before one's reaching the age of 18).
A fun way to get a feel for the phenomenon is to play with a sound editor like Audacity, mix in some beeps of varying lengths and pitches (arranged into chords, even), then show the track in Spectral view mode. You can adjust the vertical (frequency) resolution as much as you like, but doing so smears out the horizontal (time) resolution and vice versa. A note can only have a pure frequency when it is eternal, and a very short note is just a click, composed of all many frequencies.
A similar thing can be observed for signals in time and frequency domains. Signals which are non-zero for low time duration have their spectrum spread apart in frequency and vice versa. For instance, Fourier transform of an impulse (infinitesimally small duration signal) is constant ( i.e. spread over entire frequency spectrum) whereas Fourier transform of a sinusoidal signal (spread in time domain) consists of impulses in the frequency domain.
Yes. I had all sorts of confusion about Heisenberg's uncertainty till I was teaching one of my undergrad EXTC junior about Fourier and then something just clicked. Its been 13 years since but I vividly remember the moment and the insane nerd out we had after figured it out.
Bro explained the Heisenberg Uncertainty Principle in the first 1 minute of the video better than I've EVER heard anyone explain it. Makes PERFECT INTUITIVE SENSE now. Thanks so much!! Edit: I watched the rest and yes that's the less accurate version but it ended up still working for me because I didn't assume you could determine velocity by just going to the next slide because I assumed there was no next slide, which ended up working for me. However, the next explanation he gave was even better anyways so ... win win!!
Haha. Also if you keep the ball at rest on a table, now you know both its position and momentum :D. So in Feynman’s words, I would have cheated you very badly!
Heisenberg was never a confident man. One of his characteristic personality traits was his tremendous uncertainty - hence Heisenberg's Uncertainty Principle exists.
Until now I was waiting for a breakthrough that will measure an electron's position and momentum exactly. The minute I saw the "title" of this video, I knew I was wrong and that small (but persistent) itch to understand such a beautiful theory intuitively will finally be satisfied. That's my confidence level in you, and I keep recommending you to fellow physics enthusiasts.
When I was first introduced to the uncertainty principle, I understood it as a simple mathematical problem that resulted from the inaccuracy of our measurement methods. I never understood how uncertainty became some fundamental "property" , of matter . I see the NEED for uncertainty to be accounted for in every Quantum Mechanical equation ! We cannot do QM without it. But I never saw it as a fundamental property. I never understood whey some schools of Physics treated it as such. As far as I'm concerned it is just a parameter required for calculations because of our inability to measure the position or speed of a particle without changing the speed and position of the particle while measuring it.
In classical mechanics, a physical property is plotted on a real number line but in quantum mechanics, Hilbert Space is used instead, from which the probability of finding the measured physical property to be a particular real eigenvalue can be computed.
OMGGGGG VERYYY EXITED TO WATCH THIS 21 mins and 22 seconds of quantum mechanics on this channel!!! YAAAYYYYYYYYYYYY (Edit:) Nvm. I watched the video, it's a really great video, but sadly, nothing was new for me (hence didn't enjoy like I do before in this channel, Ig it's an exception for quantum physucs 😭)because I only see these types of content everywhere. His explination was what amazes me always. :) thank you sir. You're a very great teacher ❤️✨️ Keep it up!
I have watched dozens of videos on RUclips to understand the Heinsenberg Uncertainty Principle and this is certainly the best video of all. It was the one I learned the most from. Your teaching is excellent. Thank you very much. But I still don't understand one thing: given that a quantum object has the property of a wave, what does it mean to add waves to locate the object? How is this done? I understood that by adding waves to "shrink" the resulting wave and decrease the uncertainty of the position, you increase the uncertainty of the momentum, since there are several simultaneous waves (with several wavelengths mixed together), but how is this done in practice? And what does it mean? Thanks!
@@geovanejag3946 hey, thanks for sharing that. I guess I could have been clearer there. It’s not that we start with an infinite wave and then keep adding more. Instead, most quantum objects are NOT like that. They are mostly localised wave packets. Now this localised wave packet can be thought of as sum of many pure sine waves, I.e. many wavelengths, i.e many momenta. So, just to the explain this above idea, I started with a pure sine wave and kept adding them.
This is the first time I'm seeing a video of yours, and I have to say, I'm quite impressed. You've explained it beautifully. I especially love the responsible portrayal of quantum objects as neither particles nor waves, instead of both. I've recently watched the MIT's introduction to quantum mechanics lecture 1 by Allan Adams (I recommend it to everyone, the lecture 1 has no math and is super layman-friendly), and the way he explained superposition finally made it click for me - that it's not the electron "taking both paths at the same time", but rather the electron having a very weird form of existing which does not conform to our intuitions of a solid object traveling along a path - a way of existing for which we didn't really have words or metaphors for, before discovering it in QM. Even though it's basically saying that the electron doesn't make sense in the way we're used to, him putting it this way, paradoxically, makes way more sense for me than saying "it's in two places at once". Your framing of particle-wave duality felt similar, and I really appreciate it.
I had never understood this principle for like years . I looked for books after books, videos after videos. Now I understand it completely. Thank you so much
Man this is awesome! I've never understood any video about the uncertainty principle, then had QM in Uni last year, understood it from a mathy view with basis', FT and so on. But this makes so clear and easy and i can see all the math you cleverly hid in the explanation. You're awesome!
i really appreciate that you separated the sponsor from the rest of the video with timestamps and that humble "i have made a video about that but you dont have to watch it, not farming views here." and definitely your enthusiasm. very nice job, you've earned a subscriber, keep it up!! and i dont usually comment but i really wanted to let you know!
0:46 the problem with this analogy is that in this case we know exactly where the ball is, we have full information on it's location. though the photo of it is blurred, we do know that the ball is positioned on the edge of this blurry stain, not anywhere else.
Yes, you may know where it can be but there are clearly *TWO* different edges allowed by the direction of the momentum of the ball. When we measure the momentum of an electron, we also get a two-edged ambiguity which we call electron spin.
Man you are amanzingly clear and practical, it’s so important to give intuitive and practical explanations of physical, avoiding to get lost in the mathematics with no understanding of the real deal. I think you are better than many university professors (maybe you are one of them, in that case good for your students). Keep going
Excellent explanations of the uncertainty principle (indeterminacy), that is, momentum and position of quantum particles. Thank you Mahesh, you are brilliant like your sponsore
You did give us the intuition about how it works but what about the formula and that 2pi in it? I can somewhat understand how plank's constant was there but how did 2pi show up there? It could probably be related to sine waves or the waves that define the position of electron but I need a more detailed explanation about how that formula was derived so plz make a video on that also. I think we would need a understanding of the schrodinger's wave equation (I already know about that though) so you may make a video related to that first and I will be curiously waiting for both of them.
It has to do with whether the Hertz frequency variant of Planck's constant matters, or whether the radian frequency version of Planck's constant matters. The standard formula with Planck's constant uses Hertz frequency, which is E=h*f for the energy of the photon. Planck's constant therefore has the units, Joules per Hertz, and is the energy of a hypothetical 1 Hz photon. The reduced Planck's constant, hbar, is h/(2*pi). This is what you'd get if you replace E=h*f with E=hbar*ω. The value of hbar has the units of Joules per (radian per second). It's very common in differential equations, that the radian frequency is directly determined by the coefficients of the diffEQ, rather than the Hertz frequency. You may be familiar with this, from the frequency of a mass/spring being given by ω=sqrt(k/m), while the equivalent formula for Hertz frequency will be this divided by 2*pi. This is because the calculus of trig functions is most elegant, when the trig units are radians, rather than full cycles or degrees. You end up accumulating chain rule coefficients, if you try to make it work with other angle units.
Love this! I am seeing so many relations in the world of physics and appreciate growing in understanding. I appreciated learning to the level of being able to teach the idea, although it would also be good to learn the math behind it too. So a question I thought of worth for Gemini or ChatGPT that gave a non-definite relationship was, "And what would the relationship be thereby from the wavelength of a proton to its constituent quarks?" Then ask, "So do quarks have a wavelength?" You'll get into the de Broglie equation and quark confinement.
This is the best science channel on RUclips. The way you address common misconceptions about these principles is immaculate and have really enhanced my understanding of the subject
This was the best short vid on Heisenberg uncertainty that I have seen on youtube! Thank You! I think you were so genuinely excited that you forgot how to pronounce probability, hiliarious! I am glad you referenced the Feynmann Lectures, and I plan on reviewing them!
Oh! let me show this video to Feynman, last time he was curious whether Mahesh is interested in Heisenberg Uncertainty Principle or not.❤ Thanks for the explanation 😊
There's nothing particularly innovative about these explanations. It's been done thousands of times before in books and lectures and is probably taught in just about any beginner quantum mechanics university lecture, or even in high school. He just presents them very nicely.
As a fresh out of highschool-going into college student this was really enlighting. Could you please make a video in Schrodingers equation and put some intuition into it. The math really overwhelms the whole idea of it.
Uncertainty in measuring particles exists because until measured they exist in a future state. Because causality has a speed limit (c) every point in space where one observes it from will be the closest to the present moment. When one looks out into the universe they see the past which is made of particles (GR). When one tries to measure the position of a particle they are observing smaller distances and getting closer to the present moment (QM). The wave property of particles appears when we start trying to predict the future of that particle. A particle that has not had an interaction exists in a future state. It is a probability wave because the future is probabilistic. Wave function collapse is what we perceive as the present moment and is what divides the past from the future. GR is making measurements in the observed past and therefore, predictable. It can predict the future but only from information collected from the past. QM is attempting to make measurements of the unobserved future and therefore, unpredictable. Only once a particle interacts with the present moment does it become predictable. This is an observational interpretation of the mathematics we currently use based on the limited perspective we have with the experiments we choose to observe the universe with.
Thanks for presenting physics in an intuitive way I have spent my entire 11th frustrated having not been able to feel the concepts But now that I have got a feel of it I feel the ecstasy just as you
Nice video and good thought process. I think the hardest part of all of this is that any explanation we try to come up with is founded in our own human experience. That experience is and must be filtered by the nature of our senses, the way our brain works, our macroscopic scale of living, and our cultural way of thinking. In other words, the nature of our existence biases us in a way that makes us WANT to explain things that are outside our experience using things that are inside our experience . And sometimes, like with quantum stuff, that doesn't work so well. So, while the math may work, an intuitive grasp always elides us.
This explaination is about how λ relates Position of a particle (as an analogy). Which it demonstrates very well. λ is defined as the wavelength of the probability wavefunction after all. Of course it will relate to position. By the very definition it will!! But De Broiglie's Hypothesis is that p (momentum) relates to λ in the physical world. Which is the crux that is hard to understand (or relate to).
I started learning uncertainty since grade 9, whenever this topic came up I tried my best to understand it but always failed, none of the explaination on books, internet fulfilled me. I wanted to learn the actual concept behind this, whether is it technological limitation or is it a universal truth. Now I’m in second year of college, finally understood the concept thanks to you,I can peacefully sleep rn
When I first learned about Heisenberg's uncertainty principle 40 years ago at Caltech, I thought of the analogy of taking a picture of a fast moving object using a short or long exposure time (or two short exposures spaced some short or long time apart). 40 years later, this is the first time I've seen someone else use the same analogy. I don't know why it's not used more often. It seems obvious.
Two things I cannot understand. 1. For a single wave function if the wave stretches infinitely and we are saying ∆x = ∞, and if there is a finite amplitude, does that mean the wave has infinite energy? 2. For a standing wave of an electron, won't the position be finite?
Mahesh Yes thank you. When I put together in my head some of the other explanations. This is really helpful. I congratulate you on your approach to explaining the difficult. A few months ago I was asking about about the length of a photon. Now it makes a little more sense why they were having difficulty answering it. Keep up the good work. Richard Feynman is proud of you!
please dont stop....We will keep support...These kind of videos and explaination are not so much online...U will reach heights one day..and your videos going to change our life ofcourse ❤️❤️❤️
5:31 “ electrons are not particles“ in a particle detector we see electrons as particles. So ultimately they must be particles. There’s something about their motion that causes them to move in a way that seems like there is an interference pattern.
We don't "see" electrons as particles, particle detectors are built with the idea that a particle and a (quantized) wave are the same thing on a quantum scale. We don't see a particle, as we fundementally lack te means of distinguishing the two at quantum scale (presumably because they are the same concept), we just see an electron. The name particle detector is arbitrary, it's called that because "wave detector" is a less clear name (since there are non-quantum waves, unlike with particles). It very well could've been called wave-particle detector or silly detector or even Frank really
This was such an incredible explanation that also showed the nonexamples that I would always get hung up on. My question now is why/how do we know that the uncertainty principle is true?? Guess I have some more studying to do! Looking forward to watching more of your videos!
Wonderful video. This is a description of (or an approach to) the uncertainty principal that I have never heard. Just as you promised, it feels much more intuitive now. So much more to learn and understand... I look forward to your next video.
Thank you so much for making a video that explains this intuitively! I'm hopefully going to start studying physics at university fairly soon, and I was quite intimidated by quantum mechanics. I thought I had to learn a lot about how the equations work before understanding things like this, but through this video I managed to already get an intuitive understanding, which will probably help me understand and use the equations later on.
This video fulfilled many of my curious questions about this amazing mechanisms,and gave rise to many new curiosities. I must Thank you for that my friend...
one thing in the which i did not understand was about the stability of atom. you said that due to very high velocity or momentum the electron will not fall but will move outward. so my question is ,' how the electron will move outward as the nucleus is positively charged? should not the electron be attracted instead of pushing it outward? thanks in advance for such a beautiful explanation
Like literally I want to thank you so much. First you stated this great work.( RUclips) Second it's helping a lot of people to understand concepts much better. I really want to meet you someday
Hi mahesh, great video! Thanks for the simple explanation, I enjoyed it a lot. Absolutely unrelated…but can you do a video on the constant “permittivity of free space?” Never understood what it was or why it’s important…but it shows up in almost all E&M equations
Please don't stop making these kind of priceless videos. Your subscribers may be a small number relative to other content creator but I bet your viewers are regular.
I want to start by saying that this is the best explanation of the math and the concepts that I have ever heard. That said, how does one add wavelengths? I would assert that this explanation indicates that electrons do not exist as we understand existence. More appropritely, if momentum is conserved, every electron observed in a different location is a different electron. It is not that we find an electron in different places, it is that everywhere we look we find different electrons. And that, to me, reveals a problem with how we view energy. Are we, perhaps, looking at this wrong? It works in math but not reality?
So annyoing that I always thought electrons are particles and waves at the same time - and that we as humans just cannot imagine that they are both. But now I know and I subscribed.
Omg! I was just thinking about exploring this topic since my teacher couldn't explain very well, and your video came in my recommendation. Thanks!!! - Love from BD
Heisenberg gets pulled over by the cops, and they ask him "Do you know how fast you were going?", Heisenberg says, "No.. but I know exactly where I am".
Bhai i have been suffering from the bug of Heisenberg's uncertainty principle for 3 years but at last to i set free from it. Thanks for setting me free from the bug. huge respect forever gratefull to you
Great video, love the channel. Quick question about what you said at 20:17, how/why does increased uncertainty in momentum cause an increase in velocity?
Love your enthusiasm!! Very hard to understand quantum objects, but I understand that you cannot treat them as normal macroscopic objects. I’m probably confused on a little higher level than before!
In Abhidhamma, Quantum Superposition is Water, Energy is Fire, Mass is Earth and Spacetime is Wind. Except Quantum Superposition can only perceived by the mind, all other are physical objects.
It is a very good explanation.. but at the end of the video when you try to explain why electrons don't fall into the nucleus.. you have presented the electron as quantum object .. and the nucleus as a classical partical.. although it is also a quantum object
When we add 2 waves, due to destructive interference, the uncertainty in position decreases. But the other wave could be another quantum particle as well, so are we decreasing the uncertainty in location for both the particles together??? And if so then adding multiple waves would decrease the uncertainty in location but as a collection of particles together, we couldn't figure it out for 1 particle/wave ALONE(while uncertainty in momentum just keeps increasing)??
But returning to the analogy in the beginning: what is preventing us from measuring the position of the electron several times very rapidly and then determining its momentum from that?
Basic QM postulate: measuring changes the wave function (projects to an eigenstate), so if you measure position several times, after the first time it will be a different state, with a different momentum (even different momentum distribution), not the original state we wanted to know about.
One small detail I'd like to add to this great video. In your example, you consider the quantum particles without a 0 uncertainty momentum to be "anywhere in the universe" with the same probability, which can be misleading. It's not wrong, but you must add the confinement in which your particle lives, otherwise you are literally considering the whole universe, which is a bit large to imagine. In fact, the probability density function |Psi|^2 defining the quantum particle position should add to one ON THE CONSIDERED SPACE. If you consider a box, and the particle is in there, your considerations hold there too, so if you know perfectly the momentum, you can only say that the particle could be anywhere in the box with the same probability. One cool mental experiment is trying to reduce the box size over and over, the modulus wave function squared should always be 1 in the considered space 😌
I never before understood that the Heisenberg's Uncertainty Principle was a fundamental law. I thought that it was more of an observation. My mind is blown. Thank you!
To try everything Brilliant has to offer-free-for a full 30 days, visit brilliant.org/FloatHeadPhysics . You’ll also get 20% off an annual premium subscription. Also FAQ
1) What does it mean to add two waves together?
I could have been clearer here. The bottom line is since a wave packet can be mathematically constructed by adding lots of pure sine waves of different wavelengths (Fourier series), a wave packet contains multiple wavelengths. So, an electron can be thought of as a wave packet HAVING multiple wavelengths, and hence HAVING multiple momenta.
2) What's the intuition behind energy time uncertainty?
If you hear a tone for a small time, you are unsure about it's frequency. (You don't know if it's a pure sine wave or not). This means you are unsure about it's energy (E = hf). But since the time interval was very small, you are pretty accurate the absolute time value when you made the measurement.
On the other hand if you hear a tone for a long time, you become more sure about it's frequency. (You have much better idea about the repeating pattern). This means you are more sure about it's energy. But since the time interval was large, your accuracy about the absolute time when you made the measurement went down!
Shoehorn Dirac's Equation into this explanation 😊
Man you are the biggest badass physics teacher of all times.... realy a genious...
psi(relief)
I have one for you
What was the temperature of the film inside the camera while being on the Moon?
Sir
Can you please explain how time is related to motion
I love how every time you make a video like this you talk as if you brought the scientists back from the dead and had lunch with them to make this video.
Bold of you to assume he didn't.
Yeah at first I found it patronising, but then I realised it is the perfect way to explain things. The conversation is the stepping stones to understanding 👌
Haha, when you read well written books, that's exactly what it feels like. I kid you not! (Try the book, 'surely you are joking mr. Feynman'. It's so nicely written, you feel like Feynman is sitting next to you explaining his life)
You should do one about Feyman’s “why”? It is amazing!
@@Mahesh_Shenoy"Curiosity is the spark that ignites the flame of discovery. Embrace your curiosity, ask questions, seek answers, and never stop wondering about the world around you. For in the pursuit of knowledge, you shall find the secrets of the universe, and the universe shall reveal its secrets to you."
Remember, science is a journey, not a destination. It's a mindset, a way of thinking, and a passion for understanding the world. As a scientist, you'll encounter challenges, failures, and setbacks, but also moments of triumph, wonder, and awe.
So, cultivate your curiosity, stay curious, and never lose your sense of wonder. The world needs more curious minds like yours, eager to explore, discover, and push the boundaries of human knowledge.
Now, go ahead, ask a question, design an experiment, collect data, analyze results, and draw conclusions. The scientific method is your tool, and the universe is your playground. Happy exploring!
Almost 20 years ago, I first came across the uncertainty principle in Class XI Chemistry studying the atomic structure.
This is the best explanation yet. Indeed intuitive.
And over the years, I've realised that it's not that some subjects and some topics are tough, it is the quality of books and quality of the teachers that make a difference!! And if you're not in luck with the teacher's quality, do get good quality books!!
This is how I feel too! To have a teacher or a book that makes a subject feel easy is a blessing. And it makes you wonder if some subjects aren't intrinsically harder, but are rather just taught poorly.
I am currently studying atomic structure, which is why I came to this video
This is genuinely the best science education channel out there man. Have never left any of your videos without having learned something new or in a better way than I previously understood it.
ScienceClic is also one channel, it is unfortunately one of only 3 complete explaining channels I found.
Agree
@@c.jishnu378 What are the other ones?
@@alejandrocastellanos7139 This, ScienceClic and Eugene Physics, though the last one's animation is a bit old school.
Just subscribed! 😃
The sign of a great genius is to be able to explain a complex subject to an idiot, like me, in a way I can understand! Thank you so much!
He explained it well. Actually, the formula actually applies to all waves. You would just use the frequency instead of the momentum for non-quantum objects.
But be careful Quantum Physics is FICTION. Like many other pseudo-sciences. Like faster than light travel, time travel to the past, and other dimensional universes. Those quack do like he did he explains something true and then switches to his pseudo-science
A sign of a smart person is being able to recognize that they do not understand something. You would be startled by the percentage of people who accept concepts that they misjudged to have understood.
Mahesh… that was exceptional! Thank you… my uncertainty on this is now far more certain while making my certainty more uncertain!!
I didn't expect to find you here, love your videos!
Thanks a lot :)
Same for me. I find the quantum world very strange and confusing, even more the more I learn about it. I'm trying to get accustomed to these explanations but have still a long way to go. I always wonder how these quantum effects add up to the predictable, deterministic macroscopic world we live in!
@@Mahesh_ShenoyHi! Could you please explain the physical meaning of adding another wave to the electron wave (I mean does it mean shooting another electron to the original electron)
@@Grecks75
If you understand geometric wave optics with its wave interference and superposition, you can understand quantum mechanics quite "intuitively" (intuition is a form of education and according to Albert Einstein, education is the layer of prejudices laid down upon oneself before one's reaching the age of 18).
A fun way to get a feel for the phenomenon is to play with a sound editor like Audacity, mix in some beeps of varying lengths and pitches (arranged into chords, even), then show the track in Spectral view mode. You can adjust the vertical (frequency) resolution as much as you like, but doing so smears out the horizontal (time) resolution and vice versa. A note can only have a pure frequency when it is eternal, and a very short note is just a click, composed of all many frequencies.
I really love this guy's teaching style, his knowledge, and his excitement for physics. Mahesh is unique.
A similar thing can be observed for signals in time and frequency domains.
Signals which are non-zero for low time duration have their spectrum spread apart in frequency and vice versa.
For instance, Fourier transform of an impulse (infinitesimally small duration signal) is constant ( i.e. spread over entire frequency spectrum) whereas Fourier transform of a sinusoidal signal (spread in time domain) consists of impulses in the frequency domain.
That's becuz Heisenberg uncertainty principle is a result of a more general uncertainty that arises due to the wave nature.
Yes. I had all sorts of confusion about Heisenberg's uncertainty till I was teaching one of my undergrad EXTC junior about Fourier and then something just clicked. Its been 13 years since but I vividly remember the moment and the insane nerd out we had after figured it out.
Bro explained the Heisenberg Uncertainty Principle in the first 1 minute of the video better than I've EVER heard anyone explain it. Makes PERFECT INTUITIVE SENSE now. Thanks so much!!
Edit: I watched the rest and yes that's the less accurate version but it ended up still working for me because I didn't assume you could determine velocity by just going to the next slide because I assumed there was no next slide, which ended up working for me. However, the next explanation he gave was even better anyways so ... win win!!
and that is the LESS accurate version!
That's why we're here every time he uploads
And then he explains that this intuitive explanation does not really work. Watch the rest.
Haha. Also if you keep the ball at rest on a table, now you know both its position and momentum :D. So in Feynman’s words, I would have cheated you very badly!
Heisenberg was never a confident man. One of his characteristic personality traits was his tremendous uncertainty - hence Heisenberg's Uncertainty Principle exists.
He was not an ignorant man. He was confident in the uncertainty.
Until now I was waiting for a breakthrough that will measure an electron's position and momentum exactly. The minute I saw the "title" of this video, I knew I was wrong and that small (but persistent) itch to understand such a beautiful theory intuitively will finally be satisfied. That's my confidence level in you, and I keep recommending you to fellow physics enthusiasts.
are you satisfied, i mean we still know nothing we are just giving theories .
When I was first introduced to the uncertainty principle, I understood it as a simple mathematical problem that resulted from the inaccuracy of our measurement methods.
I never understood how uncertainty became some fundamental "property" , of matter .
I see the NEED for uncertainty to be accounted for in every Quantum Mechanical equation ! We cannot do QM without it.
But I never saw it as a fundamental property. I never understood whey some schools of Physics treated it as such.
As far as I'm concerned it is just a parameter required for calculations because of our inability to measure the position or speed of a particle without changing the speed and position of the particle while measuring it.
In classical mechanics, a physical property is plotted on a real number line but in quantum mechanics, Hilbert Space is used instead, from which the probability of finding the measured physical property to be a particular real eigenvalue can be computed.
OMGGGGG VERYYY EXITED TO WATCH THIS 21 mins and 22 seconds of quantum mechanics on this channel!!! YAAAYYYYYYYYYYYY
(Edit:) Nvm. I watched the video, it's a really great video, but sadly, nothing was new for me (hence didn't enjoy like I do before in this channel, Ig it's an exception for quantum physucs 😭)because I only see these types of content everywhere. His explination was what amazes me always. :) thank you sir. You're a very great teacher ❤️✨️
Keep it up!
I have watched dozens of videos on RUclips to understand the Heinsenberg Uncertainty Principle and this is certainly the best video of all. It was the one I learned the most from. Your teaching is excellent. Thank you very much. But I still don't understand one thing: given that a quantum object has the property of a wave, what does it mean to add waves to locate the object? How is this done? I understood that by adding waves to "shrink" the resulting wave and decrease the uncertainty of the position, you increase the uncertainty of the momentum, since there are several simultaneous waves (with several wavelengths mixed together), but how is this done in practice? And what does it mean? Thanks!
@@geovanejag3946 hey, thanks for sharing that. I guess I could have been clearer there. It’s not that we start with an infinite wave and then keep adding more. Instead, most quantum objects are NOT like that. They are mostly localised wave packets. Now this localised wave packet can be thought of as sum of many pure sine waves, I.e. many wavelengths, i.e many momenta.
So, just to the explain this above idea, I started with a pure sine wave and kept adding them.
This is the first time I'm seeing a video of yours, and I have to say, I'm quite impressed. You've explained it beautifully. I especially love the responsible portrayal of quantum objects as neither particles nor waves, instead of both. I've recently watched the MIT's introduction to quantum mechanics lecture 1 by Allan Adams (I recommend it to everyone, the lecture 1 has no math and is super layman-friendly), and the way he explained superposition finally made it click for me - that it's not the electron "taking both paths at the same time", but rather the electron having a very weird form of existing which does not conform to our intuitions of a solid object traveling along a path - a way of existing for which we didn't really have words or metaphors for, before discovering it in QM. Even though it's basically saying that the electron doesn't make sense in the way we're used to, him putting it this way, paradoxically, makes way more sense for me than saying "it's in two places at once". Your framing of particle-wave duality felt similar, and I really appreciate it.
This is the first time I've come close to understanding this topic
Great work.
Marvellous and astounding explanation I've ever seen , how do you simplify all these terrific topics ?
Don't forget about Diracs Equation also & Maxwells Equations and the Pauli Exclusion Principle 😊
I had never understood this principle for like years . I looked for books after books, videos after videos. Now I understand it completely. Thank you so much
Wow, wow, wow! The first 60 seconds puts it into a brilliant perspective
Man this is awesome!
I've never understood any video about the uncertainty principle, then had QM in Uni last year, understood it from a mathy view with basis', FT and so on.
But this makes so clear and easy and i can see all the math you cleverly hid in the explanation. You're awesome!
i really appreciate that you separated the sponsor from the rest of the video with timestamps and that humble "i have made a video about that but you dont have to watch it, not farming views here." and definitely your enthusiasm. very nice job, you've earned a subscriber, keep it up!! and i dont usually comment but i really wanted to let you know!
0:46 the problem with this analogy is that in this case we know exactly where the ball is, we have full information on it's location. though the photo of it is blurred, we do know that the ball is positioned on the edge of this blurry stain, not anywhere else.
Yes, you may know where it can be but there are clearly *TWO* different edges allowed by the direction of the momentum of the ball. When we measure the momentum of an electron, we also get a two-edged ambiguity which we call electron spin.
@@solconcordia4315 very interesting observation, thank you
your enthusiasm and fascination is contagious. Wonderful!
Man you are amanzingly clear and practical, it’s so important to give intuitive and practical explanations of physical, avoiding to get lost in the mathematics with no understanding of the real deal. I think you are better than many university professors (maybe you are one of them, in that case good for your students). Keep going
Excellent explanations of the uncertainty principle (indeterminacy), that is, momentum and position of quantum particles.
Thank you Mahesh, you are brilliant like your sponsore
You did give us the intuition about how it works but what about the formula and that 2pi in it? I can somewhat understand how plank's constant was there but how did 2pi show up there? It could probably be related to sine waves or the waves that define the position of electron but I need a more detailed explanation about how that formula was derived so plz make a video on that also. I think we would need a understanding of the schrodinger's wave equation (I already know about that though) so you may make a video related to that first and I will be curiously waiting for both of them.
Yea, I ran out of time for that. You can derive the expression using the single slit experiment actually. It's pretty cool.
It has to do with whether the Hertz frequency variant of Planck's constant matters, or whether the radian frequency version of Planck's constant matters.
The standard formula with Planck's constant uses Hertz frequency, which is E=h*f for the energy of the photon. Planck's constant therefore has the units, Joules per Hertz, and is the energy of a hypothetical 1 Hz photon.
The reduced Planck's constant, hbar, is h/(2*pi). This is what you'd get if you replace E=h*f with E=hbar*ω. The value of hbar has the units of Joules per (radian per second).
It's very common in differential equations, that the radian frequency is directly determined by the coefficients of the diffEQ, rather than the Hertz frequency. You may be familiar with this, from the frequency of a mass/spring being given by ω=sqrt(k/m), while the equivalent formula for Hertz frequency will be this divided by 2*pi. This is because the calculus of trig functions is most elegant, when the trig units are radians, rather than full cycles or degrees. You end up accumulating chain rule coefficients, if you try to make it work with other angle units.
Happened upon your channel today! You’re an amazing teacher - I’ve learned sooo much for the very first time! You rock! Cheers from Texas mate! 🎉🎉🎉
Love this! I am seeing so many relations in the world of physics and appreciate growing in understanding. I appreciated learning to the level of being able to teach the idea, although it would also be good to learn the math behind it too. So a question I thought of worth for Gemini or ChatGPT that gave a non-definite relationship was, "And what would the relationship be thereby from the wavelength of a proton to its constituent quarks?" Then ask, "So do quarks have a wavelength?" You'll get into the de Broglie equation and quark confinement.
don't use AI. pls. I assure chat GPT doesn't know jack about proton structure.
Such a wonderful explanation❤️
This is the best science channel on RUclips. The way you address common misconceptions about these principles is immaculate and have really enhanced my understanding of the subject
This was the best short vid on Heisenberg uncertainty that I have seen on youtube! Thank You! I think you were so genuinely excited that you forgot how to pronounce probability, hiliarious! I am glad you referenced the Feynmann Lectures, and I plan on reviewing them!
Oh! let me show this video to Feynman, last time he was curious whether Mahesh is interested in Heisenberg Uncertainty Principle or not.❤ Thanks for the explanation
😊
How do you even come up with these intuitive explanations man? I genuinely want to know.
There's nothing particularly innovative about these explanations. It's been done thousands of times before in books and lectures and is probably taught in just about any beginner quantum mechanics university lecture, or even in high school. He just presents them very nicely.
As a fresh out of highschool-going into college student this was really enlighting. Could you please make a video in Schrodingers equation and put some intuition into it. The math really overwhelms the whole idea of it.
Ive been a fan since ur 'why is the speed of light constant' video! U explain SO WELL. Pls dont stop making videos!!!
Uncertainty in measuring particles exists because until measured they exist in a future state. Because causality has a speed limit (c) every point in space where one observes it from will be the closest to the present moment. When one looks out into the universe they see the past which is made of particles (GR). When one tries to measure the position of a particle they are observing smaller distances and getting closer to the present moment (QM). The wave property of particles appears when we start trying to predict the future of that particle. A particle that has not had an interaction exists in a future state. It is a probability wave because the future is probabilistic. Wave function collapse is what we perceive as the present moment and is what divides the past from the future. GR is making measurements in the observed past and therefore, predictable. It can predict the future but only from information collected from the past. QM is attempting to make measurements of the unobserved future and therefore, unpredictable. Only once a particle interacts with the present moment does it become predictable. This is an observational interpretation of the mathematics we currently use based on the limited perspective we have with the experiments we choose to observe the universe with.
You couldnt have come up with a more confusing explanation if you tried lol
Just tell me you wrote this to flex
You shouldn’t state this like a fact when it is your personal speculation.
is it like a copy pasta now, I can see this comment on multiple such videos.
@@drdca8263 well you stated your comment like it’s a fact. Why do you get to but I don’t?
Nicely done! Your enthusiasm is contagious. What fun!
Thanks for presenting physics in an intuitive way
I have spent my entire 11th frustrated having not been able to feel the concepts
But now that I have got a feel of it I feel the ecstasy just as you
Plot twist: Albert Einstein denied the credibility of the uncertainty principle
😮
Yes but he can't get a unifying theory before his death
Nice video and good thought process. I think the hardest part of all of this is that any explanation we try to come up with is founded in our own human experience. That experience is and must be filtered by the nature of our senses, the way our brain works, our macroscopic scale of living, and our cultural way of thinking. In other words, the nature of our existence biases us in a way that makes us WANT to explain things that are outside our experience using things that are inside our experience . And sometimes, like with quantum stuff, that doesn't work so well. So, while the math may work, an intuitive grasp always elides us.
Hey!!! Thank You veery much... I understood. You explain in very practical Manner with no tons of maths. But a sense of logical explanation... ❤
This explaination is about how λ relates Position of a particle (as an analogy). Which it demonstrates very well. λ is defined as the wavelength of the probability wavefunction after all. Of course it will relate to position. By the very definition it will!!
But De Broiglie's Hypothesis is that p (momentum) relates to λ in the physical world. Which is the crux that is hard to understand (or relate to).
How does lambda relate to the position?
I started learning uncertainty since grade 9, whenever this topic came up I tried my best to understand it but always failed, none of the explaination on books, internet fulfilled me. I wanted to learn the actual concept behind this, whether is it technological limitation or is it a universal truth. Now I’m in second year of college, finally understood the concept thanks to you,I can peacefully sleep rn
When I first learned about Heisenberg's uncertainty principle 40 years ago at Caltech, I thought of the analogy of taking a picture of a fast moving object using a short or long exposure time (or two short exposures spaced some short or long time apart). 40 years later, this is the first time I've seen someone else use the same analogy. I don't know why it's not used more often. It seems obvious.
Excellent explanation. I always understood the 'what' of uncertainty ( x vs p), but until now, not really the 'why'. Many thanks.
Two things I cannot understand.
1. For a single wave function if the wave stretches infinitely and we are saying ∆x = ∞, and if there is a finite amplitude, does that mean the wave has infinite energy?
2. For a standing wave of an electron, won't the position be finite?
Are you giving jee?
@@-_-h1 Why do you ask?
I love physics because of guys like these
you have to make a quantum series.. you explain it soo well
Mahesh Yes thank you. When I put together in my head some of the other explanations. This is really helpful. I congratulate you on your approach to explaining the difficult. A few months ago I was asking about about the length of a photon. Now it makes a little more sense why they were having difficulty answering it. Keep up the good work. Richard Feynman is proud of you!
please dont stop....We will keep support...These kind of videos and explaination are not so much online...U will reach heights one day..and your videos going to change our life ofcourse ❤️❤️❤️
Best video on the topic. Thank you so much! Mind blown. Finally everything makes sense.
This channel is probabbely the most intuitive physics channel on youtube.
This is awesome! I used to think it's about the interference from the observer, but now I understand! Thank you!
5:31 “ electrons are not particles“ in a particle detector we see electrons as particles. So ultimately they must be particles. There’s something about their motion that causes them to move in a way that seems like there is an interference pattern.
We don't "see" electrons as particles, particle detectors are built with the idea that a particle and a (quantized) wave are the same thing on a quantum scale. We don't see a particle, as we fundementally lack te means of distinguishing the two at quantum scale (presumably because they are the same concept), we just see an electron. The name particle detector is arbitrary, it's called that because "wave detector" is a less clear name (since there are non-quantum waves, unlike with particles). It very well could've been called wave-particle detector or silly detector or even Frank really
ok, even the first minute blew my mind, great job like always man!
This was such an incredible explanation that also showed the nonexamples that I would always get hung up on.
My question now is why/how do we know that the uncertainty principle is true?? Guess I have some more studying to do! Looking forward to watching more of your videos!
Wonderful video. This is a description of (or an approach to) the uncertainty principal that I have never heard. Just as you promised, it feels much more intuitive now. So much more to learn and understand... I look forward to your next video.
Mahesh you are lowkey the best in intuitively explaining complicated subjects like these, thank you for these video's.
Thank you so much for making a video that explains this intuitively! I'm hopefully going to start studying physics at university fairly soon, and I was quite intimidated by quantum mechanics. I thought I had to learn a lot about how the equations work before understanding things like this, but through this video I managed to already get an intuitive understanding, which will probably help me understand and use the equations later on.
Nice! That’s the most comprehensible explanation of Heisenberg’s Uncertainty Principle that I’ve heard anywhere. Thank you.
I didn't think I can understand quantum mechanic intuitively until I see your video :D keep up the good work bro! Thank you so much.
This video fulfilled many of my curious questions about this amazing mechanisms,and gave rise to many new curiosities. I must Thank you for that my friend...
one thing in the which i did not understand was about the stability of atom. you said that due to very high velocity or momentum the electron will not fall but will move outward. so my question is ,' how the electron will move outward as the nucleus is positively charged? should not the electron be attracted instead of pushing it outward? thanks in advance for such a beautiful explanation
Like literally I want to thank you so much. First you stated this great work.( RUclips) Second it's helping a lot of people to understand concepts much better. I really want to meet you someday
Hi mahesh, great video! Thanks for the simple explanation, I enjoyed it a lot. Absolutely unrelated…but can you do a video on the constant “permittivity of free space?” Never understood what it was or why it’s important…but it shows up in almost all E&M equations
A very nice and coherent explanation of the underlying maths that make this work. The underlying maths is basically the principle of superposition.
Concept of stability of atoms brilliantly explained. Thanks Mahesh.
You are the greatest teacher of all time ❤🎉💯
man these videos make me smile they answer all my questions
You have such joy when you teach. Thank you.
Woww I loved it .. I would like to have whole course from yi sir 👐🏻👐🏻
Excellent presentation, such a simple demonstration with profound implications.
Please don't stop making these kind of priceless videos. Your subscribers may be a small number relative to other content creator but I bet your viewers are regular.
I known the uncertainty principle, but I had never connected it to the atom stability.
It's really eyes opening.
Thank you
I want to start by saying that this is the best explanation of the math and the concepts that I have ever heard. That said, how does one add wavelengths? I would assert that this explanation indicates that electrons do not exist as we understand existence. More appropritely, if momentum is conserved, every electron observed in a different location is a different electron. It is not that we find an electron in different places, it is that everywhere we look we find different electrons. And that, to me, reveals a problem with how we view energy. Are we, perhaps, looking at this wrong? It works in math but not reality?
The tennis ball analogy is brilliant.
So annyoing that I always thought electrons are particles and waves at the same time - and that we as humans just cannot imagine that they are both.
But now I know and I subscribed.
Please make a video on Schrodinger equations😢
You feels like myself studying Physics interestingly... I like your videos very much.
Omg! I was just thinking about exploring this topic since my teacher couldn't explain very well, and your video came in my recommendation. Thanks!!! - Love from BD
Keep up the good work, thanks to you I'm seen as the smartest Gr.10 in physics.
You're so good are explaining things!
Heisenberg gets pulled over by the cops, and they ask him "Do you know how fast you were going?", Heisenberg says, "No.. but I know exactly where I am".
Bhai i have been suffering from the bug of Heisenberg's uncertainty principle for 3 years but at last to i set free from it. Thanks for setting me free from the bug. huge respect forever gratefull to you
Feel happy whenever you come with a video...❤
Very intuitive explanation, as always! Can you explain please the uncertainty principle for energy and time too?😊
Great video, love the channel. Quick question about what you said at 20:17, how/why does increased uncertainty in momentum cause an increase in velocity?
Thanks and when is your other new video coming?
Love your enthusiasm!! Very hard to understand quantum objects, but I understand that you cannot treat them as normal macroscopic objects. I’m probably confused on a little higher level than before!
Your lectures are absolutely FANTASTIC!!!!!!!!!!!!OUTSTANDING
In Abhidhamma, Quantum Superposition is Water, Energy is Fire, Mass is Earth and Spacetime is Wind. Except Quantum Superposition can only perceived by the mind, all other are physical objects.
Love the concept... Can you address other electron shells?
It is a very good explanation.. but at the end of the video when you try to explain why electrons don't fall into the nucleus.. you have presented the electron as quantum object .. and the nucleus as a classical partical.. although it is also a quantum object
You can have energy stored as a standing wave and if there is no losses it will be within it's limits for ever.
When we add 2 waves, due to destructive interference, the uncertainty in position decreases. But the other wave could be another quantum particle as well, so are we decreasing the uncertainty in location for both the particles together??? And if so then adding multiple waves would decrease the uncertainty in location but as a collection of particles together, we couldn't figure it out for 1 particle/wave ALONE(while uncertainty in momentum just keeps increasing)??
But returning to the analogy in the beginning: what is preventing us from measuring the position of the electron several times very rapidly and then determining its momentum from that?
Exactly, it's not about measuring. Electron's don't have a definition position/momentum to begin with.
Basic QM postulate: measuring changes the wave function (projects to an eigenstate), so if you measure position several times, after the first time it will be a different state, with a different momentum (even different momentum distribution), not the original state we wanted to know about.
One small detail I'd like to add to this great video.
In your example, you consider the quantum particles without a 0 uncertainty momentum to be "anywhere in the universe" with the same probability, which can be misleading. It's not wrong, but you must add the confinement in which your particle lives, otherwise you are literally considering the whole universe, which is a bit large to imagine.
In fact, the probability density function |Psi|^2 defining the quantum particle position should add to one ON THE CONSIDERED SPACE. If you consider a box, and the particle is in there, your considerations hold there too, so if you know perfectly the momentum, you can only say that the particle could be anywhere in the box with the same probability.
One cool mental experiment is trying to reduce the box size over and over, the modulus wave function squared should always be 1 in the considered space 😌
This is brilliant. I never heard the uncertainty principle explained like this. Wow.
I never before understood that the Heisenberg's Uncertainty Principle was a fundamental law. I thought that it was more of an observation. My mind is blown. Thank you!