The ABSURDITY of Quantum Mechanics at LARGE SCALES!

REFERENCES

CHAPTERS
0:00 Magic is not real, I guess
1:33 My inspiration
2:40 Superposition
4:20 Quantum tunneling
5:37 Heisenberg Uncertainty principle
7:54 Double slit experiment
9:40 Why don't we see quantum behavior at macro scales?
10:45 What is Decoherence
11:20 Real examples of Macro scale quantum physics

SUMMARY
What If our everyday life was based on quantum mechanics? What if macro objects behaved like quantum objects?

If you are in a classroom with 4 chairs, you would appear to a second student, to be sitting on all the seats at once. But as soon as he touches one of the chairs, you appear in one of the seats sitting by yourself. And he is then able to take a seat. You were in a superposition, which is the ability of a quantum object such as a photon, electron, atom or anything sufficiently isolated, to be in multiple positions at the same time until it is measured.

This comes from the Schrodinger equation which contains a term called the wave function. The wavefunction for an object contains all the information that describes the quantum object, such as its position, spin, momentum, etc. Objects can take on almost any value according to the wavefunction prior to measurement. The wavefunction only tells us the probability. But once a measurement is made, the properties of the particle gets fixed to only one of the possible states. Note that a measurement is any kind of interaction and is a physical process that does not require a measurer.

Let’s say you hit a squash ball against the wall in front of you. The ball disappears and shows up on the other side. This phenomenon is known as quantum tunneling. In quantum mechanics, when a quantum object like an electron encounters an energy barrier, like a wall, there is a non zero chance that it will end up on the other side of the wall. This is because its wavfunction extends to all of spacetime, meaning it can in principle end up anywhere, including the other side of the wall.

But can any player hit the squash ball in the first place? If the squash ball is a quantum object, it is subject to the Uncertainty Principle. This principle says that there is a fundamental limit to how precisely we can know certain combinations of properties of a particle, such as its position and momentum. So if the player knows where the ball is, he won't know how fast it's going. And if he knows how fast it's going, we won't know where it is. So taking a swing, he may not hit the ball. This is not due to an observer effect. It’s not a limitation of what we can measure. It is a limitation of what we can know.

If a squash ball machine creates and shoots squash balls onto the wall for practice purposes, you would not actually see any balls coming out of the ball machine. All you would see is balls bouncing off the wall in front of you. What's happening is that the balls coming out of the ball machine are in superposition. They only become localized and visible after they have interacted with the wall in front of you. Before this happens, their location could be anywhere in the court. The various locations would have a probability associated with them. They could even be outside the court due to quantum tunneling.

Why don’t we actually see this in our everyday experience? Why don’t these quantum behaviors appear in our macro world? Do the laws of quantum mechanics apply only at micro scales? No, the laws of quantum mechanics apply to everything. But the effects of quantum mechanics are too small to be noticed.

Subatomic and atomic scale objects act like waves, and so behave like quantum objects. But large objects are made of a huge number of individual waves, since a squash ball is made of almost 10^15 atoms. All these waves of atoms act in a disorganized and random way. Their individual waves interfere with each other, and average out to zero. This disorganized wave-like behavior is called “decoherence” in physics. And this cumulatively results in classical behavior. In order to get a macro object to behave like a quantum object, we would need all its quadrillions of individual waves to be coherent, and behave like one large wave. This is usually not possible.
#quantummechanics
#quantumatlargescales
But you should know that coherence has been achieved in some large molecules consisting of up to 2000 atoms. Other large scale quantum effects include superconductors, Bose-Einstein condensate and superfluids.

[vinvic]

I love your emphasis on the Heseinberg uncertainty being a consequence of wave mechanics as opposed to an observer effect. As a physics student I can attest this misconception is everywhere in pop science ! Great video all around.

[DanteGabriel-lxbq]

I cannot express how good you are at explaining this stuff, you deserve so much more!

[tomaaron]

I’ve been a geophysicist for 45 years. I must thank you for re-instilling the sense of wonderment I felt in my younger days. I watch your presentations then find myself pondering it all in those quiet times of contemplation when hiking or cycling.

[claudiorassouli]

Your animations about physics are some of the best anywhere. I love how you point to formulas and break them down. How long does it take you to make the animations? Do you do them yourself? Either way it is very impressive.

[elpuerco]

Decoherence perfectly describes my mental state 😂

Excellent explanation and video, as always, professor.

[adels]

I agree with the other comment here, I cannot express how grateful I am for having discovered you. Really like your style of explaining complex problems.

[jmcsquared]

It should be noted, decoherence is often quoted as a solution to why we never see quantum behavior on macroscopic scales, but this isn't the full story. Decoherence is just a term used to describe what happens when a huge quantum system's many parts interact, both with each other and with their environment. Everything gets scrambled up, and the system's parts begin to behave according to classical probability rules instead of the Born rule. What this does model is the emergence of classical statistical mechanics.

But there is no mechanism that decoherence provides that explains the quantum measurement problem. As a system begins to interact with its environment, the state of the system, at least in principle, remains stuck is a massive entangled superposition, all the way to the macroscopic level. Interactions by themselves do nothing, according to Schrödinger's equation, to force a system to leave a superposition of states. This only appears to happen (for some reason) once the system interacts with measurement devices.

Therefore, it's still an interpretive question, and an unanswered one at that, to ask what the state of the system at large scales.

[mmogaddict]

I am already living the Quantum Mechanical lifestyle, most of the time I know neither where I am nor where I am going.

[rwarren]

Thanks for another great video! I love being able to understand the basics of Quantum Mechanics. Oh and great splash page. 😎

[kallesamuelsson]

After another 1000 explanation clips or so I just might start to grasp this subject. It's so fascinating but so confusing. Keep up the good work Arvin!

[magellantv]

Wow! This was amazing and incredibly well done 👏

[sillyproofs]

That! Is why people have difficulty understanding the Quantum World. Because we view it in terms of own perspective of life. This video serves to bridge the gap between the micro and the macro! It well pioneers a very good way of approaching Quantum Mechanics!

[aryansingh]

I'm a big fan of you, Arvin! You made everything complex as hell simple as a piece of cake.

[mariobrambilla]

The most excellent explanation I’ve ever seen on this subject. Congratulations Arvin! Keep going!

[surajvkothari]

Content like this is a blessing! Such a unique take on quantum behaviour compared to lectures!

[theshowmanuk]

Absolutely superb demonstration ! I am sure this will encourage students (young and old) to get into the maths and physics to get a greater understanding and appreciation of quantum mechanics.

[twilightbts]

Great! Perfect video for my doubt for why quantum mechanics doesn't apply for us. Thank you.

[SpaceCakeism]

13:03
Even if we shrank ourselves to the quantum scale, we wouldn't be able to perceive quantum interactions; reason being that first of all, we'd have to reduce the amount of photo receptors in our eyes to 0, and second being that the wavelength of light would have to be too short for us to see with our eyes... (Or even survive, given that air molecules would be as large, if not larger than you; even if you magically didn't die from all the other things you'd be lacking, like your entire body's structure, considering how squished it'd have to be...)

Of those two choices, I think it's fair to say that projecting quantum behavior to macroscopic scales is the safer (twice over) bet, however difficult that may be, at least the experimenter would survive. ultimately, I think it's better to continue on the general path we're already on, where we improve our detectors, and have them do the observing for us.

[alimmaqsa]

I love when u say :" right now".👍

[timjohnson]

Very will done, Arvin! I'm reminded of George Gamow's Mr Tompkins series. He did a few short illustrative stories on quantum effects if we could see them such as "Quantum Billiards" and "Quantum Jungles".