What Heisenberg's Uncertainty Principle *Actually* Means
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- Опубликовано: 8 июн 2024
- Let's talk about one of the most misunderstood but awesome concepts in physics. The Heisenberg uncertainty principle. Or maybe it should be the Heisenberg 'fuzziness' principle instead? Would that confuse less people?
I love how you represented likelihood in position with faded particles. Brilliant!
phthisicy chill out dude, all he said was that he like the idea of a gradient of colours of the particles. Not everyone has a fucking brilliant 9000 IQ like you.
Hey Nick
or else, do you want her to use the word "interpretation interpretation interpretation...... "like you!!!! i shouldn't have subscribed to your channel #asylum
Do you know any YT channels that explain the experiments used to prove these principles?
the two of you make videos together
German here, "Unschärfe" is a term from photography meaning *blurriness*/ "unfocusedness." I don't know whether this is where Heisenberg got the name from but maybe the idea is that you can't focus on two different objects simultaneously if they have a different distance to the camera. One of them will always be out of focus.
Also, in German there are two names for the HUP, "Unschärferelation" (= blurriness relation) and "Unbestimmtheitsrelation". "Unbestimmtheit" means indefinite (or vague). I think *indefiniteness* is a much better name to describe this phenomenon than uncertainty.
We should call it the *Fuzziness Principle*
What +Zardo said. Also the photography term "scharf" is a metaphor, literally meaning _sharp_ (e.g. referring to a knife).
The uncertainty principle is an artifact of probability theory being applied to a physical system: Chebyshev's inequality.
fuzzyness might work too.
Zardo Dhieldor Heisenberg's blurry theorem.
I love how my video is 8 mins but The Science Asylum says the same thing better in just 3. Go check it out and say I said hi: ruclips.net/video/skPI-BhohR8/видео.html
Ya, but. I like your voice better. And the illustrations are nice too.
Hey, don't second guess yourself! You did a great job! :)
So about your question at the end f your video, it sounds simple: No, because after measuring the momentum, the uncertainty regarding the position increases so the particle can't be (for sure) at the same place, but something else left me thinking:
What if you were to measure the momentum of a particle alone, stop and after a short while measure it again, would the results be the same or each time you stopped measuring it would go back to the superposition making the following result inconsistent with the previous one?
UncommonReality The evolution of a wave function is given by the Schrödinger equation. If you measure it, the wave collapses to an eigenstate. If you wait, then the wave evolves in a certain way which is determined by the Schrödinger equation. Don't ask me though what this equation does with eigenstates!
I love how your video was 8 minutes though. 5 minutes was you setting up the questions and dispelling the false answers. The only reason I knew the right answer was because you did such a good job of explaining everything in your previous videos, but it's nice having the specific myths dispelled.
I used to believe in the Heisenberg Uncertainty Principle. But now I'm not so sure.
HUP is mathematics of waves and so..u have to belive it bcz its mathematically accurate and u cant prove it wrong..
@Mark Reynolds lol
hehe mark
@@anandsuralkar2947 anything that is based on experimentation is open to be proven wrong. Don't be overconfident, it's not going to age well. Our time period probably has just as many misconceptions about physics as they had 1000 years ago.
So you are uncertain, which proves the princlple
I don't remember subscribing to this channel, but a big thanks to past me for doing it
same
For me, the confusion came from Stephen Hawkin’s explanation in A Brief History of Time
I just watched three of these videos and I have to say I loved them. Your simplified but still somewhat technical explanations strike just the right balance for where I'm at as an amateur physics fan. Definitely subscribed!
I like calling it the "spreading" principle instead, e.g. a particle state is necessarily spread in position and/or momentum space.
Took a couple days to get to this one (Sorry!) but this really clarified the uncertainty principle for me. I went with 3 at the start, but there were definitely some mechanics I didn't really understand. Looking forward to the more technical video, although who knows if I'll understand it...
On the homework, wouldn't measuring the momentum put the position back into flux, so that if you measured position afterwards it'd be in a random place again? Otherwise you'd have simultaneous exactly-accurate information for the location and momentum, and the fact that you can't do that is kind of the point of the principle in the first place.
Also, I had a question on the equation: If you've just measured the location of the particle, isn't ∆x zero, at least momentarily? there's no uncertainty at all: it is where your result just said it was. And if it's zero, then no matter how large ∆p is, the product of the two is zero. Assuming I didn't just overturn almost a century's worth of quantum theory, what stops that from being the case? Does a little bit of uncertainty remain, even when measured? or do we just use an arbitrarily small non-zero number to represent no uncertainty, instead of zero?
no one ever gave an answer :(
@@damimz7026 true
@12tone I read this in your voice
That’s a great question and I’m not sure if I’m too late but actually if the delta x is zero then delta p would have to be equal to infinity
Or something like that I’m still not too sure
Just finished my high school studies and done a final from higher physics. As particle physics is partly in the curriculum, we covered this topic too, I remember that we specifically learned the second explanation.
However, I always fellt this part too slippery, and all our theachers were very unsure when asked for another explanation. I'm not surprised that this (among a few others) came out to be false. There are a lot of cases when because of simplifying we are taught the wrong answer.
Welcome back!
I'm sooo glad I found your channel! I find your presentation to be both pleasant and informative. Every discourse is directed at some audience and I think I'm right in the audience you're aiming for. Anyway, thanks so much for this video.
Aw, thank you! I'm so glad I managed to get at the right level for you :) I find that very tricky- so I'm glad it worked for you.
Thank you for your wonderful videos, I've watched them all up to this one and have enjoyed them all. I've read up on a fair bit of quantum mechanics and watched other videos on the subject but my understanding of certain areas in the maths department had a some holes. Thanks to you, your videos have helped clarify these parts. I will continue enjoy watching so keep up the good work!
I feel like there's something amazing about using Alice iconography to talk about quantum mechanics, a subject so keenly tied into complex numbers, when it's been theorized that Alice in Wonderland was Lewis Caroll's jab at complex numbers for being…well, as mad as the inhabitants of Wonderland. I love it and I'm loving your videos so far.
Alice and Bob are names used in cryptography to represent people or items A and B. See en.wikipedia.org/wiki/Alice_and_Bob . An alphabetic list is included in that article.
The uncertainty principle is an artifact of probability theory being applied to a physical system: Chebyshev's inequality.
How so? I don't know much about probability theory, but the HUP is about _two_ distributions, not one, while the Chebyshev's inequality I see on wikipedia seems to involve only one distribution (Even the "vector" version seems to me to lead to something quite different from the HUP). I'd be interested to learn why I'm wrong. :)
Maybe something can be said when the two distributions are the squared norms of two complex functions that are one the Fourier transform of the other?
BTW, "quantum" probability is different from "classical" one: the lattice of "quantum events" is non-distributive (aka non-Boolean), contrary to the case of measurable subsets of a probability space. (Maybe that's more about "logic" than probability; anyways...) And the "quantumness" manifests itself for non-commuting observables, which is exactly where the HUP occurs.
Super happy that you are back. I love your videos, they are very clear.
You have the BEST channel about explaining this stuff in an entertaining way!
Studying all this now in my second year at UQ, great vids!
UQ!? I love that place.
Damn, I picked 1. because I was picturing the equation in my head lol
That σ_x.σ_p ≥ ħ/2
I interpreted 1. like "when the error on x is small, the error on p is large"
The problem with this is that error implies difference between "real" value and obtained value, which is untrue because there is no such thing as a real value. That's why we use uncertainty instead, which is related to the standard deviation of the distribution
Thank you so much for your videos. This really cleared up questions I had when I hear about the HUP (at least the way it's usually described).
I have my quantum mechanics final in 2 hours and you absolutely saved me with these videos. Your explanations are amazing! Thank you!!!
Oh I didn't know RUclips had this poll feature. It even works on mobile, neat!
Unschärfe literally means unsharpness (if that's not an English word it is now), in this case like when you look through a lens and a distant object appears unfocused and fuzzy. They also sometimes use Unbestimmtheit which might have been the word translated into uncertainty and it's probably the worst translation because to me (especially for this case) it's closer to undecidedness (as in the particle hasn't decided in which particular state it is), and even in my language we say it like that.
unsharpness would be bluntness I think
I would suggest Unschärfe=blurriness and Unbestimmtheit=indefiniteness/indeterminacy.
+Zardo Dhieldor well blurriness would be more locigal than bluntness....
I really don't believe that this has anything to do with blades! :D
"Oh, my sword's blunt again! Damn Heisenberg!" :P
Unless it's a reeealy small blade :D
Yea I actually like indeterminacy more than undecidedness, though at this point we're just finessing the language.
Looking Glass, you are so awesome! You deserve more subs, or a shout out from 3B1B or Minutephysics or something.
That video was awesome! Now i actually understand the Heisenberg's uncertainty principle. Please keep making videos. I'm a physics student and i find your channel very cool and your videos easy to understand. Subscribed as well. Thanks a lot! :)
Whoa, this video was AMAZING! (I voted 1) :D
I love the way you communicate physics and your videos help me understand some weird concepts.
I really appreciate the time and effort you put in them. (I'm studying physics but i haven't reach anything quantum yet.) Greetings from Chile! :P
I don't know you, I am not sure who you are, but I like you.
This video wades back into the swamp of "interpretations of quantum mechanics", so there is bound to be disagreements.
Most people would agree that description 2 is inaccurate, and glosses over the intrinsic, fundamental role the HUP (or more generally, non-commutation) plays in QM.
But the question of whether or not a system has a property prior to measurement has different answers for different interpretations. The Copenhagen interpretation, for example, only concerns itself with what measurement devices report when they correlate with quantum systems. It makes no propositions about the ontology of an unmeasured quantum system, and limits itself to an epistemic understanding of experimental outcomes and their correlations.
Under my favourite interpretation (Decoherent Histories), however, we can make statements about the properties a system has without the context of a measurement. We can say a particle has a position whether or not it is measured, and we can say a particle has a momentum whether or not it is measured, provided we are careful with our syntax. Unlike hidden variable theories, the Decoherent Histories interpretation uses the vanilla Hilbert spaces of QM and doesn't introduce any new mathematical structures.
arxiv.org/abs/1105.3932
tl;dr Different interpretations of QM map the formalism of QM to different propositions about reality. Therefore, for better or for worse, different interpretations will map the HUP to different propositions about reality. So pinning down what the HUP means is difficult.
Then you really don't understand Quantum Physics.
You could try to explain why you think he is wrong instead of being a dick.
@@edwardblois8646 Maybe not but who does really? Einstein would have words about a lot of assumptions in this video.
Thanks a LOT for doing this....I loved it. I first went for Option 1 & 2 and now I'm converted!!
First off, I'm really enjoying your channel! You're really making me wanna go back to school and study more physics, haha.
Anyway, I kinda just started self-studying QM and I came across the pretty standard result of a photon's energy being E = hf and wanted some good intuition on why this is true.
The furthest I can get is that energy is a time-invariant quantity (or exhibits time symmetry to borrow from another one of your vids - really great vid too!), so if it's going to be dependent on any aspect of a wave, it can't be its period. At the very least, the fact that the photon's energy depends on the frequency of the wave is consistent with that idea (I think...), but I'm not fully satisfied with that idea. This is tangentially related to the Fourier formulation of uncertainty and I'm wondering if there's anything more to it. It's nearly four years since you made this, but I hope someone sees this, lol.
"The solutions to the eigenvector equations for position and momentum lead to the uncertainty principle. In other words, the wave function solution for a specific value of momentum has probabilities for the position everywhere (in the single dimension). This derivation shows that the position and momentum wave functions are Fourier transforms of each other. Thus mathematically the uncertainty principle is simply a statement about Fourier transforms."
It's not a popular position yet but I definitely think Fourier Transforms are not a tool but how the universe actually functions. I think the frequency domain is not an abstraction but, real. It's something not observable so I guess that presents a conundrum.
I really love ❤ your videos.
Aww, thank you! ☺️
At 4:50
Unschärfe literally means something in the range of
"fuzziness", "being blurred" and "un-sharp / not sharp".
The term Unschärfe is usually used in the context of optics, e.g. a blurry picture a horrible lens
Angelic voice and explanation that is exactly, what we call "layman's terms". Very nice, you have a new subscriber and fan!
Hi Mithuna!
So great to have found you again on RUclips!
Will be telling my 12s to watch your channel!
Where are you based at the moment and what are you up to?
You can use my school email to answer. Still the same! 10 years later!
Mr Carbo
You said in the video that when you measure a particle you collapse the wavefunction, AND that if you measure the particle again, you will get the same result (2:18 "if you measure it again, it will certainly be in this place") because you had collapsed the wavefunction.
I'm not convinced that's true. I once looked for an experiment that clearly showed what happens in sequential measurements of a single particle, and I couldn't find one. As far as I can tell, it is impossible to track and measure a single quantum particle multiple times. The act of measuring is so disruptive that the system has completely changed.
so when we do measure it twice, it is in the same place right?
Yes, except when you measure the position the first time the speed is randomized so if you wait a while it will have moved.
This is the explanation I was looking for. Thanks!
It's nice that you are back!
im having a hard time explaning to my friend why QM is not only about statistics.
what is the fundemental diffrence between saying i have uncartainty and that the partical is in superpition and saying that theres for exsample 1/5 chances of finding it somwere in the system
Hmmm, if you're dealing with statistics with "classical" assumptions you wouldn't expect, for example, the probability distributions for position and momentum to be coupled the way HUP predicts. Seems to me that when you're doing statistical analysis you need to have some knowledge of how the components of the system is expected to behave, and QM is significant because it produces a different version of that knowledge than classical mechanics.
But a particle does actually have a position and a momentum in Bohmian mechanics.
yup, I should make a video about HUP in bohmian mech one day.
why does quantum theory is more widely accepted (used) than the pilot-wave, although being very counter-intuitive itself? Is there any experiment proves that pilot-wave theory is wrong, or maybe it has some flaws? Or is it just a matter of preference?
I mean like, pilot-wave theory gives a very clear image compared to quantum theory. Why most scientists out there prefer to use quantum theory, even in high-school I only got to study quantum mechanics (I didn't get pilot-wave).
No, in Bohmian mechanics a particle only has a definite position. Momentum is stored in the wavefunction.
+Tadho because Bohmian mechanics is not an interpretation of quantum mechanics. It's a distinct theory with distinct predictions, and it gives incorrect ones. It also conflicts severely with special relativity, whereas quantum mechanics does not.
omg please do. i just got into bohm mech and now revising all of this quantum stuff makes the bohm interpretation so confusing. Because how do they all fit together? Doesn't bohm mech disagree with superpositions? Or does it acknowledge it stochastically?
good point! Ok, I think Bohmian mechanics deserves a proper explanation on this channel.
Love your videos . Found you after your latest video appeared in my suggestions . Happy that I did .😃♥️
I think the best way to translate Unschärfe is blurry or "blurryness".
Image you try to see underwater, it's hard to clearly tell where exatly stuff is and the vision is blurred.
In German, when Unschärfe is used, it is mostly referred to vision too.
Great video, thank you :)
I voted 2. 100% of votes are 2 now. I feel bad for making the polls so wrong :(
No that's great :P
As soon as someone says a physical phenomena is not about measurement it ceases to be physics. ALL physics is about measurement. I didn't like any of the three given definitions.
The Heisenberg Uncertainty Principle is:
There is this mathematical thing called the wavefunction - it's a wave. The wavefunction always has two variables that represent two things that are observable (observables) like position and momentum (they have to be non-commuting). An example would by y = sin( k x ) (the full equation is both real and imaginary) The Uncertainty Principle is all about the wavefunction. The fundamental non-cummuting variables are either k x (momentum position) or w t (energy time). How to interpret it beyond this we don't know.
You can sum up these waves like this (y is the wave amplitude) y = Σ Ai sin(ki x) or like this y = Σ Bi sin(k xi) for all i
No matter how you try to sum up the waves there will always be a little spread in x or k. You must ALWAYS treat one variable like its spread out throughout all values and the other like its a sum of states. The spread is only reduced in the "wavelike" variable by increasing the number of summed waves of different i in the other particle-like variable. For example you can go to the extreme and set ki = π (so momentum is one value) and that's the ONLY ki. If you do this then using either equation you don't get a wave if x is only one value. If you choose the left equation the x variable is spread throughout the entire x dimension. If you choose the right equation you can only get a correct k = π result if you sum up infinitely many xi that do not cancel out to infinity. In either case x is either the wavelike variable that doesn't have y canceling out to 0 at infinity OR you must have infinitely many xi s making x again spread out.
You must always have the ability to transform from one equation to the other. The only way to reduce the spread in x of the left equation is to get y = 0 by the sum of waves canceling. The only way to reduce the spread in k of the right equation is to get y = 0 by the sum of waves canceling. Even classically uncertainty exists in waves. We CAN make wave pulses or directed beams by superimposing many waves on top of each other (even a "freak" wave in a pool). That wave follows the same math and logic. The only difference is that in QM the parts of the wave function where we know for sure we didn't find the particle disappear (to where? and how? we don't know). The wavefunction does NOT, REPEAT NOT, necessarily collapse down to a single point. We couldn't test this if we wanted to. There's always a tiny spread in practice depending on the experiment done (we will learn the particles in some fuzzy little region). When the wavefunction "collapses" down in x then it must spread in k. Uncertainty in k doesn't spread to infinity (good thing) because we NEVER localized x down to a true point. When the wavefunction collapses it still has a little bit of spread centered on some point. That's not a "classical uncertainty" but the actual wavefunction.
I have no idea what the actual wave equation physically represents (no one does). However, wavefunctions do NOT randomly alter on their own and ALL changes to the wave equation result from some interaction AKA (if we're doing it) some form of measurement (if it's an experiment its should be part of the setup). There is always some Feynman Diagram, some change in the wavefunction by something we (or nature) did, and some observation. For example with the single slit experiment we put a barrier in the path of the particle. If the particle didn't hit the barrier that is something we know based on information we learned about the particle. We measured the particle simply because we know if it didn't hit the barrier then that part of its wavefunction decoheres from it's future position. We know something about the particle via something we did without necessarily touching it. Later when the particle hits the screen we know it's localized to within say 1 nanometer. The spread of x affects the spread in the momentum of the emitted photon. If on the other hand the photon hits a large mirror we may know with great accuracy which direction the photon will reflect (the k) but the photon's wavefunction was never localized to a single atom but rather spread over the entire mirror.
Another good video. I would love to hear more about why time and energy are complimentary pairs impacted the the uncertainty principle. The other item I really really would like to see you develop is a video on weak measurements, what it is, what is it used for and can it be used to create a picture of this superposition state?
you are awesome and the explanations were very cut and dry and easy to understand thanks :)
1:34 Let me just stop you right there, that's not what Quantum Mechanics says, that's what the Copenhagen interpretation says. De Broglie Bohm Theorem begs to differ.
I agree. Here I was taking QM to mean standard QM, as I personally see BM as an alternative theory. But I made a video about this recently :) ruclips.net/video/r0plv_nIzsQ/видео.html
well, OBVIOUSLY if you don't measure the particle, you won't know where it is and how fast it's going! ;)
But if you measure it YOU WONT KNOW where it is AND how fast its going, You can measure one with arbitrary precision but not the other.
No, it's not that obvious. In classical physics, if you know the initial position and momentum of the particle and the law of motion, you can determine without a doubt which position and momentum it will have at any given time, even without measuring. You can obviously measure it, if you wish, but you'll get, apart from experimental errors (which you can make as small as you want), exactly the number that you predict with the theory. The theory can predict the numbers that you'll get by measuring.
In quantum mechanics, this is not the case. It's fundamentally different.
@@TheSghetty Actually, HUP applies both to QM and classical mechanics, but in our size scale, the precision error is so small that it can't be seen.
Thank you so much for that very interesting video! Really helped my fix some of the misconseptions about the HUT :)
you are great your explaination was very good help me in coming out from misconception of hesinburg uncertainity
The video says that the uncertainty principle is not about measurement.
I differ, since it´s about the linear operators that represent the observables of position and momentum.
So it´s all about measurement.
Any other interpretation makes assumptions about the underlying reality that are pure speculation.
YES! Thank you! (Those assumptions are the mystical axioms of the Copenhagen interpretation.)
I think this is an imposition of Copenague interpretation... There are alternatives... At least 4 valid alternative interpretations made by physics... Copenague isn't only physics but philosophy... and bad philosophy... Bohr's philosophy...
I feel like she doesn't understand the implications of her point two. They perfectly explain why the hup exists, including the math she showed.
Andrew church, her mere use of superposition injects Bohr into this. I don't believe in superposition at all. It's a copout. Bohm had it right.
The uncertainty principle is an experimentally verified fact. Its general form involves two observables A, B and an inequality with a very *specific* lower bound. And the Copenhagen interpretation is the only theory so far that could explain the lower bound correctly for arbitrarily many choices of the pair A,B which may be arbitrary functions or functionals of positions, momenta, spins, and/or fields.
1. Any realist theory that denies superpositions will predict that you should always be able to reduce the lower bound further i.e. closer to zero. The correct experiment results will always get a specific lower bound proportional to a *UNIVERSAL* constant for various forms of A and B. Therefore realist theories are falsified.
2. When you replace delta A delta B with k {A, B} you will always get k to be equal to *the Planck constant* regardless of choice of A, B, etc. With realist theories you have to tune an infinite amount of parameters for your model to get the same k for all these experiments.
Why? Because your realist theory doesn't fundamentally associate the observable quantities with linear operators, good luck getting the correct lower bound for the right hand side...
Even if the uncertainty is just an artifact of the apparatuses' imperfection, these apparatuses are still governed by the laws of physics and the laws of physics must have some explanation why their minimum uncertainty always seems to be what the uncertainty principle claims, right?
This is an obvious yet huge task that none of the Bohmian and similar theories has even attempted to solve. I think that all of them know that only the proper apparatus of quantum mechanics (in which the observables really are linear operators, and the calculable predictions really are subjective probabilities of outcomes) can achieve this triumph. The goal of the Bohmian, many world, and similar theories is just to fake quantum mechanics: to ""embed"" quantum mechanics in some ""realist"" framework and claim that it's the better one. (and the popsci audience loves it because it "makes more sense" to them than linear operators on Hilbert space)
edit. removed offensive remarks :))
@@arguewithmepodcast Superposition does kind of imply nondeterminism, and to that extent is incorrect in Bohm theory.
@@gillbates2685 Can't agree. HUP is not part of QM or any of its interpretations. It is a law of measurement due to the inverse precision between dependent variables such as location and velocity or time and frequency.
Brilliant explanation. Thank you for assistance!
thanks for clearing this up you explained this very well
I still think point 2 is correct.
although it is true but it has nothing to do with Heisenberg's principle... it can even be explained using classical physics
I feel like it's more like when disproving a perpetual motion machine: for a specific machine, one can make a detailed proof as to why it's not going to work (analogous to point 2), or one can invoke the much more general and higher-level second law of thermodynamics (analogous to HUP). Do you think my feeling is correct? If not, why not?
Are superpositions real ? Is anything real ? What does it mean to be real ? - I would say that to be 'real' is to have definite position at all times. Philosophically you can make a strong argument for 'reality', it's not proof, but compelling. From here, this grounding, you can resist the QM non-sense that negates reality and ask why does it appear to be so. I am not saying QM is wrong here, just that any inference that wishes to trade away 'reality' so lightly is misguided. There is only non-local hidden variable theory to my mind that does this.
I'd like to add, the notion of a state 'IS' a superposition is really just a slight of hand move by the physicist to give QM some semblance of as if he's talking about reality, superposition is really a transplanted word to remove from the mathematical model used (V_SP) of a linear combination of 'states' which is an entirely abstract notion.
That is a very strange definition of realness. You seem to have arbitrarily picked that definition to claim that it "negates reality."
What philosophical principle allows you to require extremely tiny things to behave exactly like macroscopic objects? What philosophical principle allows you to force reality to conform to your expectations of what is sense and nonsense?
If you ponder carefully the notion that an electron has a "definite position at all times", even when it is not observed, is the real nonsense.
Physics is a lot about interpretation and, well, metaphysics. When you have a bunch equations that let you predict the outcome of certain experiments, how do explain that? You can assign an intuition to certain mathematical objects and talk about a "superposition of eigenstates" but basically that's just a convenient story to "explain" why your equations work. You can tell a different story about the same mathematics (then called a different _interpretation_) but that doesn't change the maths.
Physics often gets you in philosophical trouble.
Zardo Dhieldor
Nonsense. Physics has nothing at all to do with metaphysics. It has nothing at all to do with making up stories. It is about making mathematical models of reality, and testing those models against experiment. If theory matches experiment, the only explanation is that the theory reflects reality well. Physics can't get you into philosophical trouble; if there is a conflict between physics and philosophy, philosophy loses.
Michael Sommers I know that you can do physics without the interpretation part. As a mathematician, I never understood why physicists always struggle to motivate and interpret their results. It always seemed to me like making up funny stories.
A very very beautiful, clear, eloquent and intuitive explanation. You first gave 3 possible statements of the principle so people can compare it with their own conception. I've never seen such an approach. Also, your beautiful drawings attract people's attention because they get frustrated by all those elaborate geometrical diagrams, greek symbols etc. Now your video helps them to think more clearly about the process of quantum phenomena like Hawking Radiation, why weak force called weak, Bose-Einstein Condensate, at low energy why the vacuum is not really a vacuum? if quarks contribute only 1% of mass then from where proton gets its 99% mass? etc. From your videos, people can compose their own thought experiments more precisely like "if an electron gets caught inside the container whose walls are shrinking then after a while, would electron still be found in the container or not, as shrinking volume makes electron's position more accurate (uncertainty decreases) so by trade-off relationship, uncertainty in momentum will increase". I think helping others to understand how the universe works at the fundamental level is the greatest service to mankind. Very good job. Please, when you get free time write a book on Quantum Reality with all these Beautiful drawings. I'm sure it will be a bestseller.
1st video on RUclips I have seen that define the uncertainty principle correctly.
All other videos , actually, define the observer effect and they use '∆' at the position of ' variance' ( small sigma).
A special thanks to you
Make more about QM, please!!! This is so good.
Tks, I'm understanding it better all the time. This was a eureka moment for me.
that gave a very clear picture of HUP.......was very helpful..................thank you so much
More of this in the world would be really appreciated
Love this video. Will be doing videos about quantum computing at any point? I was trying to explain to a friend how quantum computers don't "try every answer at the same time" and then get "the right" answer somehow, but while I know enough to know that explanation is wrong, I realized I wasn’t sure how to give a better one without committing a different but equally reprehensible sin. :P
Thank you ! easy to understand
Best, clearest explanation I ever heard!
If you take the wave function in terms of position, you can transform it to be in terms of momentum (The wave function can hold all information possible about the particle). But in so don't, the math inevitable shows the HUP. This is where the law originated from. If you take a wave function of one position, and transform it to momentum, you find you have basically infinite uncertainty.
*doing
These videos are awesome. Thank you.
Thank you so much, it was very helpful and informative. As I learned in school the principles of unvertainty and superposition are due to the wave-particle duality of atomic and subatomic entities.
Greetings LGU. It is great to see someone put in the effort to present and discuss some of the most important (and widely misunderstood) ideas in modern physics (says someone who has run into more quantum-woo than most...but perhaps not as much as thyself) with humour and insight - kudos!. If I am reading this correctly, you are trying to get across the message that the lower bound on positionXmomentum is a fact of nature and not an artifact hampering our means of querying nature. Then again, I'd wonder if , say, I were to have considerable interest in the career of some random particle, would you agree that another way of looking at this would be in terms of the precision I can achieve with regard to my "beliefs" on the state of the particle in the wild (sans measurement)...and of course, if I've never measured, I can construct a family of beliefs to account for the various states I could compute (not going to...there is not enough caffeine in the world to help me with this :)) for this unique particle, and in each instance, the belief would be constrained by the "uncertainty". Of course, this assumes that my beliefs have a robust correspondence to quantum reality (superposition etc. included), and that there is no information lost in their computation. Does this sound pertinent or am I getting something wrong (quite possible as I am not a proper physicist) ?Also, I am curious as to what you make of "randomness"...this video suggests there is true randomness in nature, and I have always been uncertain about that ;) Looking forward to the derivation of HUP. Ta.
Great explanation!
your videos are so good... love them....
At 1:54 I started nodding to myself, saying, "Ah, she's describing what physicists call Collapsing the Wave Function. I wish she used that phrase specifically." Then at 2:30 you totally do use that phrase. Btw, this is an excellently explained video. Thanks!
something that stuck in my mind during this video is the veritasium video about the hup. is that video correct in its description of the hup? if not, I think a response video would be really entertaining
finally someone that explains this without assuming we can't figure it out without a lot of confusing technobabble
That was a good one... cleared it up for me, many thanks!!!
I learned something new today :P
That really opened my eyes to be honest. Great video
Really nice video. Quantum mechanics is a very misunderstood field but you manage to explain it very well. Did/do you study physics or is it an hobby of yours?
Great video! Could you do a video on whether quantum mechanics disproves determinism, or just increases the difficulty for arguing for it? Anyway, thanks for your content!
QM is not inherently deterministic or nondeterministic. That is a characteristic of interpretations of QM. Bohm is simpler because it is deterministic.
I love your videos! I am 16 but i really love quantum physics. Keep making more videos! Also my answer for the homework question is no, the position will not be the same when we measure it second time as it is changed when we measure the position of particle the first time.
Every time I watch this video I get that Eureka!! moment but I still don't understand it completely.. but I'm 100% sure that this video is THE best video on HUP in RUclips .... Thank you so much for this
Thank you! Thank you! This really cleared up questions (Brazil, 2020).
Really brilliant,fantastic representation.
How do you know the position is random? Is there a experiment that has tested whether or not the position is random, or do we assume that because we have not found a pattern?
Your videos are awesome, so lovely made
The HUP is a statement about the statistics of a large ensemble of identically prepared systems. It says nothing about a single copy of the system; and it says nothing about the precision of individual measurements (the HUP would continue to hold even if the measurement precision was literally infinite).
Yep, that is exactly right. The momentum of a single quantum is always finite (and limited by the energy in the system), no matter how high the spatial resolution of our detector is. It does not go towards infinity just because we make an aperture smaller. Having said that, a detector with high spatial resolution won't tell us the momentum of the quantum and vice versa, a detector with good momentum resolution has to be large. That's why telescopes have to made very large to tell where the light came from. Having said that, these are perfectly classical effects. They don't require quantum mechanics. One can observe them on water waves just fine.
@@schmetterling4477: I would say they're neither quantum nor classical phenomena per se. I would say in the quantum case it's true for abstract reasons (HUP can be proven in abstract QM, given a state vector) and, in the case of the wave function of a quantum particle as state vector and X and P as observables, this theorem specializes to a relation between a function and its Fourier tansform.
The latter Fourier relation (or a vector version thereof?) can also be applied to "any" function, whether it represents a classical field or a quantum wave function. I would imagine this makes particular sense when the field "is a wave" (obeys some sort of wave equation) cause then the Fourier transform tells us something about actual frequencies. Does this make sense?
@@rv706 Mathematically the uncertainty principle is a pretty trivial lemma about certain linear operators. It will show up wherever the theory has a linear vector space structure. Quantum mechanics is one example, so are all linear wave phenomena in physics and engineering. This is, unfortunately, often misunderstood.
rv706
@rv706 It is also true of single measurements of single particles.
Hey, great video! As a mathematician interested in QM I am really looking forward to the technical stuff :D
Awesome! I think it's very nice mathematically :) (well- except that position and momentum 'states' aren't actually states since they're not in L2). If you're very keen though, I have an old video on it called 'the maths behind the Heisenberg uncertainty' :)
i already knew all that, but that was a trick question, love your vids tho keep making em, thanks
Looking forward to your upcoming derivation of HUP video :)
incredible as always
What if we take second partical for 1st we measure momentum (p) other one position (x) cause they are same boom
So, do the bolder regions in position/momentum correspond to the more faded-out ones in the opposite region? I.E., the more "classical" it is in one area, the more "weird" it gets in the other? Does that make them as or similar to, interdependent variables?Edit: watched your other video, I *think* I get it clearly, the more accurate measurement you have of one, the more equally-shaded the other's possibilities get.
It has to do with measurement, I think. See my main comment.
Great video... yes, let's learn more about the genius behind them! : )
I thought that was an excellent presentation, bravo!
hey.. love the videos, but i have a question for you...
you've built up to show how with wavefunctions and superpositions , undetected particles have superpositions of speed. what i cant get my head around is that the speed of light in a vacuum is 'set', so how can there be any superpositioning going on?
or is it that its only the speed of light for 'observed' photons which is set?
please help me unravel this technicality for me!
Great stuff. One can hardly be surprised there is a lot of misunderstanding of QM given it's very strange to start with.
Can I request a future video (a series?) on the difference between quantum mechanics, quantum electro dynamics and quantum fuel theory. My potted understanding of the history is that QM had massive theoretical problems (infinities all over the place) until QED in 1949 with its "renormalisation". Is that right? The impression I get from your videos is that QM was mathematically unproblematic* from the start [* of course there was a problem that no one could properly understand it. ;-)]
I've been watching a lot of physics on RUclips and these videos are first class.
Tim J. Quantum mechanics is when the number of particles is fixed, while in quantum field theory, the number of particles can change - that's pretty much it. QED is a relativistic quantum field theory of the interaction between matter and the electromagnetic field (relativistic because it also obeys the rules of special relativity).
The issues of infinities arise in quantum field theory because, unlike standard quantum mechanics where the total energy of the system is what is important, it's actually the energy *density* that you use.
To find the total energy, you need to integrate over all of space, and these intervals are often infinite without renormalisation. Renormalisation really just means rigorously assigning meaningful values to infinite integrals.
These infinities arise in other integrals over space too, but the energy was the best example.
This is well explained video; Great
I can add here for more clarification this analogy :
If you have a specific amount of money and you want to decide to buy a house ; your decision must compromise between two options :
the size of the house and it's location
if you choose to buy a big house you can't choose it's location ; and if you prefer to chose a luxurious location you will no longer be able to specify the size of the house ; this situation occur because you have a limited a mount of money .
some one of size or location must give or at least you you can make a balance decision between both of them .
You can't decide both of them in Principle because you have a limited amount of money
the same here for quantum physics; Planck constant is similar to the limited amount of money in the analogy and the size and location are similar to velocity and position .
By this analogy one can understand WHY it's impossible in Principle to know exactly the velocity and position at the same time . which is the most difficult thing to grasp in uncertainty principle and it was to me too .
I hope this help, and thanks for this great video .
2:30 yes it IS doing what it was doing before BUT with a way much smaller deBroglie wavelength due to the entaglement interaction with the measurement instrument.
Love your videos!!, boy, was I COMPLETELY wrong about my perception of HUP. Thanks thanks and thanks again for this video
I think Jade may be wrong. See my main comment.
Hey, great video as always!! :D
Came here to clear my doubt but in the end got more CONFUSED!
I think Jade is wrong. See my main comment.
Here's my way of interpreting the Heisenberg "Unschärfe" Principle:
With light waves, there's an inverse relation between energy and wavelength.
Light waves are described by Maxwell's wave equations, and doing some funky derivations with Maxwell's wave equations gives you Schrodinger's equation.
In Schrodinger's equation, energy and wavelength still have an inverse correlation. But the energy of a massive particle is related to the particle's momentum (a la Newton's laws), and the wavelength is roughly related to how well we know its position (a la the Born Rule).
To visualize this, just imagine the wavefunction as a slope on a mountain. The steeper the slopes around the mountain, the more localized the mountain is. But the steeper the slopes, the more the mountain moves (because the Schrodinger equation boils down to k1 * d/dx = k2 * d/dt).
That's a good visualization for you in case your physics class isn't giving you a good idea of what's going on.
Random question. I haven't studied quantum physics btw but in one of your videos you mentioned about spin and that these minute particles are always in motion. If that's so, can that be a reason as to why when one repeats an experiment multiple times, there will be a possibility of multiple final positions probably because these particles will never start at the same position or direction due to the fact that they can never stay still at the start of the experiment? Or does that do too little to change the outcome?
Spins aren't inherently random, but in typical experiments you start with electrons having spins in random directions, then select for the directions you want. Similarly, the initial positions of electrons in a beam will be random only because that's how the equipment works. Physicists assume randomness because of the Copenhagen interpretation of QM, not because of QM itself. Bohm theory does not assume randomness; it is a deterministic theory.