The Heisenberg Uncertainty Principle Explained Intuitively

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An intuitive explanation of the Heisenberg Uncertainty Principle of quantum mechanics.

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*Quantum Physics Series:

*Sources*
The Blackhole Wars - Leonard Susskind
Quantum Mechanics: The Theoretical Minimum - Leonard Susskind

*Music*

[evildracko]

Heisenberg, Schrodinger and Ohm are in a car

They get pulled over. Heisenberg is driving and the cop asks him "Do you know how fast you were going?"

"No, but I know exactly where I am" Heisenberg replies.

The cop says "You were doing 55 in a 35." Heisenberg throws up his hands and shouts "Great! Now I'm lost!"

The cop thinks this is suspicious and orders him to pop open the trunk. He checks it out and says "Do you know you have a dead cat back here?"

"We do now, asshole!" shouts Schrodinger.

The cop moves to arrest them. Ohm resists.

[ericknyevz]

The cartoon faces were extra funny and adorable this video. They made me laugh a couple of times. Well done.

[Jabrils]

This was a fantastic explainer Jade! The visuals we're on point!

[senakssssarnab]

It is amazing how you uncomplicated your videos are...
You take a complex and through the use of those brilliant animations and those simplified explanations...
God, I would love to have you as my Physics teacher!!!

[JJ-kleq]

Yesterday was International Talk Like a Pirate Day and today we have this. The relationship between the days is expressed by an equation involving Walking the Planck’s Constant.

[johann]

Isn't the uncertainty in position and momentum an intrinsic property of the particles wave function and not relying on a measurement through a photon?

[StatedClearly]

So you're saying quantum mechanics does not require hippie magic? I'm tossing out my rhinestone glasses.

[vnadium]

This is by far the best and most concise and clear explanaition of the uncertainty principle I've ever heard! And I've spent a loooot of time in college.
Thank you very much Jade!

[christinew]

"Next time you think you can have your cake and eat it too, you probably can't."
-Jade the motivational speaker, 2018

[ColinBroderickMaths]

This video repeats the incredibly common confusion between the measurement problem and the uncertainty principle. They are emphatically NOT the same thing!

The measurement problem is about the fact that you can't measure something without interfering with it. Very simple and easy to understand. The uncertainty principle is about the fact that conjugate variables literally can't both exist as defined quantities at the same time. It's not that we can't accurately measure the momentum of a confined particle, it's that there literally isn't a proper momentum to measure, even in principle. This is much harder to justify and understand but is a very well understood and universally accepted facet of quantum theory. This video gets a little closer to the point toward the end, but doesn't really nail it, and spends at least the first two thirds talking about the wrong topic.

If you're not trained in physics, and often even if you are, this is a very easy mistake to make. Be highly suspicious whenever you see a video or article about the uncertainty principle, even by a usually high quality channel like this, and honestly quite often even coming from an academic. There have been a few occasions in the past when I've received messages from people saying things along the lines of "this video finally made the uncertainty principle click!" Twice from people with actual master's degrees in mathematics and physics. The link they provided made exactly this mistake. Point is, don't feel bad. Even the experts frequently confuse these two (sort of, loosely) related but very different phenomena.

[DudeWhoSaysDeez]

Intuition is so important when learning difficult concepts. Thanks for sharing this video. I hope you make more videos about how to intuitively understand more complex areas of physics.

[KhAnubis]

This video actually really helped me understand all of this a lot better! Also, now we know how much time you spend stalking old ladies.

[jekabskarklins]

This video is actually about Observer effect. It never gets to explain Uncertainty principle. Maybe someone could make it (nudge, nudge, wink, wink)

[jellyfishjelly]

Wait a moment, so when I'll have no birthday party, i should get, like, the ultimate grades!

[joshwi]

Maybe the reason fewer people came to your party wasn't because of too much study, but because you spent a year in a bush watching an elderly lady.

I'm sure Mildred would come to your birthday party though! (As long as it's not on a Sunday)

[KcMsPik]

I think for the 1st time I have understood clean and clearly the Heisenberg uncertainty principle. I badly needed this kind of teachers during my college days! But better late than never!! Thank you for this video. I will be waiting for more ☺️

[makidoko]

Jade, you definetly rock at vulgarization. And I love the misadventures of your cartoonish Jade.

[thepluckedflower]

Undoubtedly the best video of Heisenberg principle on YouTube I found so far. I am more than amazed. Great work!!

[vacuumdiagrams]

Very often people decry the first "disturbance analysis" of the uncertainty principle, suggesting that the second point of view (which involves the Fourier transform) is the better one. I like that you presented both in equal footing, because they really are in equal footing: a wavefunction is nothing but a mathematical representation of a particle's state that has built into it that kind of disturbance analysis. The fact that position and momentum are conjugate variables (that is, that they Fourier transform into each other) wouldn't make any sense _unless_ we knew that position measurements disturb momentum measurements and vice versa.

Both intuitions carry a risk though, and that is the risk of imagining that a quantum particle is just like a classical particle or just like a classical wave. Really it is neither, and we know that any naive classical hidden variables model (like one suggested by either picture) wouldn't work.

Overall this is a very nice video! I would just like to leave a couple small corrections about the slide around the 7 and a half minute mark:
1. Energy and time are not exactly complementary properties because there is no observable (no Hermitian operator) corresponding to measurements of time. In nonrelativistic quantum mechanics, time is just a parameter. The so-called "energy-time uncertainty relation" is actually a bit subtler than most quantum mechanical uncertainty relations. John Baez has an excellent discussion on the subject at
2. Entanglement and coherence are not canonically conjugate either, for the reason that neither is really a well-defined observable. We say "entanglement" and we say "coherence" mostly like adjectives, meant to describe a given physical preparation rather than be actual quantum mechanical observables. For a given system it may be possible to define observables which correspond to intuitive ideas of "entanglement" and "coherence", and those observables may be conjugate. However, depending on how you define the terms and how you think about the system in detail, you may find that an opposite idea is true! See e.g. 1502.05876. All in all, I think the terms are just too vague to be assigned a precise conjugacy relation.

[supersmashsam]

I'm quite satisfied with this video! After the comment I left in one of your previous video about how I think it's futile to try to explain quantum mechanics without the maths, it's nice to see the point of view you took this time! Keep up the good work (I know you worked hard on this one)!