What does Schrödinger's Cat explain to us?

You have probably heard of the Schrödinger’s Cat experiment on quantum mechanics but have likely struggled to understand it 😺.

Watch this video to learn more about the famous physicist’s experience related to Schrödinger's wave equation named after himself, that shows whether quantum particles exist in two different states at the same time. 🤓

#engineering #science #schrödingerscat #waveequation

[Interestingengineeringofficial]

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[shellily]

One thing is for sure ---- if you open the box and the cat is alive, its going to be very angry.

[calvinlalremsanga]

This is my 5th video trying to understand Schrodinger's cat and it's more and more thoughtless than the previous

[mayurchaudhari]

Shakespeare: "To be or not to be."
Schrödinger's Cat: purr...

[emmafranco]

Ok, so, that explains why I never understood the thought experiment to begin with... Itwas always meant to sound nonsensical

[MischaDitamparOma]

even schrodinger himself dropped the subject lol

[lesaber]

Now I understand. You put it in a way that shows it's actual simplicity. Thank you.

[FatManJackson]

When I was a small child I believed nothing in the world happened, until I saw it or heard of it in some form. As if I was a book character and the world around me was written on the go.

[abhiprakash]

What ? He developed it to show how ludicrous the explanation was but ppl thought he was supporting it. Lol 😂

[patbarr]

Excellent! I didn't realize Schrodinger was arguing *against* the idea of superposition with this thought experiment. No wonder Einstein agreed with him.

[countalucard]

If I try to think and understand this paradox I would get a headache so I will happily leave this earth not getting it at all.

[nikkitytom]

Whew! I have been distressed by this "thought" experiment for years. Now knowing it was a sophisticated prank by Schrödinger to challenge the Copenhagen Interpretation of Quantum Mechanics makes me much happier.

[wmstuckey]

Fun introduction to Schrodinger's Cat. Since this channel is Interesting Engineering, allow me to add something to it using quantum information theory.

What people fail to mention when talking about quantum superposition using Schrodinger's Cat is the difference between a classical bit of information (like a computer bit being on or off) and a quantum bit of information (a qubit). Both bits produce one of two outcomes when queried (measured), but a classical bit has only one measurement possible while a qubit can be measured in many different ways (infinitely many, actually), each with two possible outcomes.

For example, when you pass an electron through an inhomogeneous magnetic field, the electron is either deflected towards the North magnetic pole ("up") or towards the South magnetic pole ("down"). You can orient the N-S magnetic field in any direction you like and the electrons will still give one of those two outcomes, so electron spin is a qubit with two outcomes of spin "up" and spin "down" relative the the N-S magnetic field. Now suppose you pass electrons through a N-S magnetic field oriented vertically and then send those that were deflected "up" (literally up in this case) to a N-S magnetic field oriented horizontally. What do you expect to find?

Well since the electrons have vertical spin up and spin is a vector (picture an arrow pointing upward here), then you probably expect the electron to pass straight through the horizontal magnetic field, i.e., they won't be deflected left or right at all ("up" or "down" relative to the horizontal N-S field). That's because the electron's spin vector (arrow) points up which means it doesn't point side-to-side (left of right) at all, so your horizontal spin measurement of a vertical spin up electron should seemingly yield a result of zero horizontal spin. But what you find instead is that 50% of the vertical spin up electrons are deflected left ("up" towards North pole) and 50% are deflected right ("down" towards South pole). True, 50% left plus 50% right *averages* to zero, but that's not what you expect from the measurement of a vector quantity in ordinary classical mechanics. [Aside: Quantum mechanics gives the classically expected results on average over the discrete or quantum measurement outcomes.] This is quantum superposition, a vertical spin up electron is a quantum superposition of 50% horizontal spin left and 50% horizontal spin right and we write that as |V+> = |H+> + |H-> (divided by root 2 for normalization, but I don't need that to make my point).

The point here is the horizontal spin measurement of the quantum state |V+> produces each of its two "up"-"down" (left-right) results in 50-50 fashion. This is exactly what you hear people say about Schrodinger's Cat, i.e., you open the box and find the cat is dead with 50% probability or find the cat is alive with 50% probability. With that information alone, Schrodinger's Cat could be a classical bit or a qubit. If Schrodinger's Cat is a qubit, then there must be a measurement of the cat-box system like the vertical spin measurement of the state |V+> that produces |V+>, i.e., |H+> + |H->, with 100% certainty. We know the measurement "open the box" producing "Live Cat"-"Dead Cat" results in 50-50 fashion is analogous to the horizontal spin measurement of |V+>, so what is the measurement of the cat-box system corresponding to |Live Cat> + |Dead Cat> with 100% certainty in analogy with the vertical spin measurement of the state |V+> that produces |V+> with 100% certainty? And what does its outcome mean physically? If you can't articulate that measurement and outcome of the cat-box system, and every possible measurement between that measurement and the "open the box" measurement, then the cat-box system is just a classical bit ... like opening a box to find a ball or no ball. No quantum superposition there 🙂

To read more about the quantum information approach to entanglement for the "general reader, " see "Einstein's Entanglement: Bell Inequalities, Relativity, and the Qubit" due out in June 2024 with Oxford UP.

[smmchen]

After watching several videos, this was easier to understand. Thank you, I now finally understand.

[mohamedredaboulezaz]

Finally someone understands the true meaning of the experiment

[scottthompson]

I thought this video was the best explanation yet, thanks for making it. Maybe it made more sense to me because I had already watched a couple of other videos, but I still thought it was clear and made the most sense.

[Morcvert]

When I try to grasp the concept I always feel like I did understand the experiment but at the same time I didn't understand, I guess I need to be tested to figure out the real result.

[alfredzhang]

Interesting. I did not know that Schrödinger was in reality arguing against the concept of quantum superposition with this thought experiment.

[wasifasarwarifza]

You explained it in such a simple way. Thank you

[fibonaccisrazor]

This is definitely the best explanation of the Schrödinger's Cat experiment. All others have got it the wrong way around and have tried to make sense out of nonsense, leaving the viewers unnecessarily confused and even more disheartened with the complexities and paradoxes of quantum physics.

And to allude to Richard Feynman, even the best scientists don't understand quantum physics, they are merely aware of the behaviours within it and can in some cases describe it with equations.

Hope that makes sense.