Understanding Quantum Mechanics: Schrödinger's Cat Experiments 

Even Heisenberg must be uncertain about it 😉

4:37 "... cats just constantly interact with something, like air or the cosmic background radiation". Most notably, cats also _always_ interact with objects at an edge of an elevated place.

Don’t know why I can’t stop listening and learning. You are the most advanced science channel for normal people. Thanks

When Sabine explains anything, I feel I'm getting closer to understanding it than ever in my life.

Sabine, can we please have an episode discussing the implications of throwing out any one of these assumptions?

“In fact, the mere act of opening the box will determine the state of the cat, although in this case there were three determinate states the cat could be in: these being Alive, Dead, and Bloody Furious.” Terry Pratchett, Lords and Ladies

Wigner - important twist on Schrödinger's cat experiment -- wonderful step through building blocks to understanding. Worth watching again several times so it has a chance to sink in a thick skull. Marvelous, thank you !

I love when Sabine makes a video just a minute before going to the ball room.

Excelent presentation. Not that I comprehend it, I'll have to rewatch several more times before even comprehending 10%, maybe.

Each week your videos bring me to a closer understanding of physics! Thanks for your wonderful content, Sabine!

I’m a fan of throwing out point 3, the spooky action at a distance. It seems less likely to result in super confusing but technically simpler interpretations where you just have to loosen your grasp on reality to accept. That’s the same reason I like the pilot wave interpretation for the double slit experiment, because it is easier to think about (even if it’s slightly more complicated mathematically).

"A laser pulse is approximately a cat" - This sentence alone should be enough to get young people interested in physics

Excellent video. I love your position on quantum physics and I think you explain your views in a way that is entertaining and thought provoking. Thank you for all your hard work!

I love your take in the interpretations of quantum mechanics. Is something that passes by in Physics study. And I really hate Schrodinger's cat jokes because everyone misses the point completly and turns the deep phylosophic meaning aside and start talking about jokes that you already heard a million times in Grad school.

OMG the delivery of the line on Schrodinger's dog was 10/10 😂😂

You are a joy. I am familiar with most of the issues (such as this one). But, your discussions are so disciplined. For a time, I had arguments with a MW friend. When you discussed MW, I just sent him the link. Your reasoning is the same as mine, but you explain it so much better. Also, after I thought deeply about Bell, I settled on super determinism, too.

Sabine's position and explanation on this subject matter, is....once again superb!

This is so way beyond my IQ level, and yet so deliciously captivating.

Every time I watch one of your videos, I feel like I actully understand something. You are a great teacher.

As a science fiction writer, I find the multiworlds hypothesis to create the greatest temptation toward convenient plot solutions.

I love and admire this lady so much... The subject has been studied for so many years, still... Sabine's always so intelligent and so relevant.

I am not a science buff but I feel like I am beginning to understand your videos. Another great video! Thank you

Actually, Schrodinger had both a cat and a dog until he observed it.

Another wonderful video by Dr. Hossenfelder. Our thanks also for verbalizing what may rank as one of the dumbest ideas in quantum physics: "Before you measure it, the nucleus is both decayed and not decayed." Something as simple as the undecayed nucleus undergoes a transition that leaves it in a decayed state just won't do: That would be far too simple an explanation, and what's worse, completely in accord with our intuition. The fact that an atom in an excited state *spontaneously* decays to a state of lower energy evidently doesn't have any relevance when describing decaying nuclei. Schrödinger's cat is really a side show, however; the experiment that truly matters is EPR. The person who sheds significant light on that will be very deserving of the Nobel Prize.

LOVE your videos!! This is on of my favorite videos ever, thanks a lot for explaining it in such a good way :)

I agree with you. It’s determined in advance. Make the box transparent and the cat is alive OR dead. The cat whether you see or not is already in a COLLAPSED state, not in a superposition of states.

Experimental evidence suggests that the cat has quantum-tunnelled out of the box, and is squatting over the scientist's slippers with a strained expression.

Wonderful! Thank you so much for your very nice and interesting thoughts!

Brilliantly explained! Thank you so much.

Thank you, Sabine, for demonstrating the proper pronunciation of "Schrödinger".

It's no wonder there's still confusion over Schrodingers cat, the old lad forgot to factor in that they've got nine lives..

really enjoying the content keep up the good work thanks

Thank you! I just found your channel and I love it.

Should have put Pavlov's dog in the box , that mut was used to being screwed with .

I didn't understand the question at the end, but I'll watch again and pay better attention. My doggo, Sweetie, was drooling on me like Pavlov as I watched the first time.

Very good video which keeps me updated about what is happening in the field of QM interpretation. I have left his field unfortunately several years ago as I tried to prove the spontaneous decoherence of Quantum states.

I am delighted to hear Sabine, but I think the videos could be subtitled or even dubbed so that they can be seen in Brazil ... Sabine, your line of thinking is wonderful ... Thank you!

If the reason for Quantum State Superposition collapse is at 4:30, then why is the Photon Quantum State Superposition easy to observe in the double slit experiment as an interference pattern of Photons? Shouldn't the Photon interference pattern collapse with interaction of the air, heat and noise?

Thank you for this interesting video, beautiful Sabine 😍👍🔔

Your content is absolutely precious.

Thank you. Very interesting as always. It would be very interesting if you could present your view, about delayed choice quantum eraser experiments too, which I believe, are some how related to the presented issue.

Ah, this is the "Schrödinger's lab assistant" experiment, where Schrödinger notionally replaced the cat with his lab assistant. Of course, being a postdoc, he was a qualified observer able to resolve the wave function. But then he in turn was replaced by an undergraduate. Even after opening the box they were unable to determine whether he was dead, alive or just drunk.

Since you are the only physicist that has taken the effort to explain the cat in away that holds my interest freely I'm going with Superdeterminism.

Sabine, will you make a video about pseudoparticles like phonons and polaritons? Love the channel and the videos get better each time.

Sabine thank you for the awesome videos! Could you do one on superdeterminism? What makes it appealing? How does it compare to entanglement? (as far as I know these two "mechanisms" compete in explaining whats going on in the violation of Bell's inequality, is that right?) :)

Isn't the cat itself as a living being with self-awareness an observer of its own death / staying alive?

Sabine is like a favorite song. If I like the tune, I don't necessarily care what the words mean. Sabine is so smart I don't necessarily understand everything she says, but I still love listening to her.

This was a brilliant video! Thank you!

Well, in ireland we're all very religious and the missionary is considered a super position.

Most importantly, Schrödinger's cat gave rise to the BEST science joke ever: "Schrödinger and Heisenberg were driving in a car. . ." LOL!

Sharp and clear explanation 👍👍

Hard to imagine that this 11 minute video is only the tip of the iceberg! Well done Sabina!

I have a Schrodinger's lottery ticket...

Dr. H, in super determinism, when you say that it is a smooth, deterministic, and local process, does it not mean that for a short while the cat was in superposition even though that the collapse of the wave function happened before you made the observation? Is it not the same issue, regardless of how short or long time the cat was in superposition?

Sabine has a perfect voice for her videos

Some people would argue that what actually holds is spooky action at a distance (such as non-local determinant models) with no need of superdeterminism. :)

So the takeaway lesson: Schroedingers cat turned into a dog to escape the death trap, that is really an unexpected outcome of the famous experiment. But well that is how science works and we now have to look for models that could explain that. Morphing escape theory: (1/2 CxAxT + 1/2 CxAxT)box ---> DxOxG(0)box

I would give up the prohibition against "spooky action at a distance." You won't miss it, particularly if the prohibition is eased just for quantum effects. In contrast, superdeterminism implies that chance is an illusion, that everything was predetermined. For this view I have two questions: 1) What predetermines the pre-determinant? A cause infinitely far back in time? If so, nothing is really a determinant, for every apparent determinant actually has a pre-determinant ad infinitum. But if every determinant is not really a determinant, then determinism is an illusion. 2) What role would natural laws play in a super-determined universe? Natural laws are generalizations, but superdeterminism implies every event was determined specifically, in which case no generalization actually is true, in which natural laws are an illusion.

Your explanation to Schrodinger's cat is mind blowing 😊

Nicely done

"Schrodinger did not have a cat" Well... not anymore at least...

One of the better "cat videos" I've seen on RU-vid. Thanks Sabine. I think, when it comes to observations, Scientist's are too often blind, deaf regarding the voice of reason, and dumb regarding their conclusions.

I enjoy your videos so much. Free will assumptions muddy the water. Fears concerning “the destruction of falsifiability” only worsen the fog of bias clouding the way forward. Superdeterminism is the simplest explanation. We could at least start there, unhindered by fears of losing something that logically cannot exist.

I have never thought superposition was strange just mathematics you have given the best explanation.Thanks for the clear explanation.😅

An article in the mainstream media about quantum physics may include a mention of Schrödinger's cat or may not include a mention of Schrödinger's cat but before I see it I know that it will include a mention of Schrödinger's cat (usually in the first or second scene or paragraph).

Hey Sabine, one thing I've always been curious about when it comes to multiple-world (and why I personally don't like it) is that "splitting into multiple-universes" should be something of a proces and therefore take time to complete... is that something people thought about?

Nice tutorial. Thanks

Great video as usual. Physicists do not think enough about time with respect to quantum entanglement and superposition. It is possible to separate entangled particles not just by space but also by time.

Aha - Finally we find out that Schroedinger was a dog person. That explains it all. BTW - Is this why Sean Carroll (cat person) is a many worlds follower? In any case, Love your videos and presentation

I always did think schrodinger to be a dog person, with all the talk of poisoning cats.

Fascinating i always wanted to know why we don't do the Schrodinger's cat experiment for real in some sense, great explanation makes perfect sense.

Sabine, you are awesome!!!

I just watched a Veritaserum video on many worlds which included topic about the Schrö-cat. Now I see that Sabine uploaded this vid. Was that the ever-computing algorithm doing this? Tell me!

Maybe he was a dog person and probably hates cat... thats why he placed cat in a such place.... But he made that cat famous 😅😂😂

It is pleasant to hear Sabina pronounce Schrödinger properly. So many of my colleagues cannot do this. ( Also, I can still her say "Differential Equations !" )

Sabine is the best science teacher ever.

At first I thought she said "The cat is in a box with a vile person" - but you'd never get that past the ethics committee.

I’ve always had a bit of a problem with “collapsing wave functions”. In reality, we exist as a sea of oscillating quantum fields with interference causing local maxima (so they say), so this “collapse” is more that we lack the measuring techniques to determine the effect of something that is spreading out its influence over a wider and wider area. I find it difficult to imagine that there is a step change between uncollapsed and collapsed, just going up a level there is more and more entanglement going on but it becomes for all intents and purposes noise, although it is still there. Maybe there is a kind of filter effect taking place, such that at human scale quantum objects, e.g. a cat, appear to be in one position and composed in a particular way but the closer you look, the fuzzier it gets. The fundamental particles that make up the cat are pure quantum but the bulk properties approximate a cat, due the the unthinkable amount of interaction/entanglement going on all the time. Thoughts?

9:15 - I'm really not knowing any of the details on what's at stake here, but I personally feel most comfortable with the "spooky action at a distance" of the three options.

Schroedingers cat.... the most intriguing story I ever heard in physics. Schroedinger who created a thought experiment proving his own theory could not be right! Although superdeterminism is not yet proved right by experimental observation, I’ve been thinking it must be correct since I first read in Gerard ‘t Hooft articles. He did not call it superdeterminism at that time, but just determinism, and i find this term much more appropriate than superdeterminism. Im my opinion superdeterminism is just determinism which is accepted into all its consequences. Its principles are exactly the same as the philosopher Spinoza already formulated in the 17th century: everything is determined by unchangeable laws of nature. All things are connected because even ‘empty space’ is a mode of Substance and all modes are connected (although Spinoza saw this connectedness as a pure mechanical connectedness, it is a remarkable intuition which is now in another form found in quantum field theory: the fields are everywhere). Superdeterminism is the simplest solution to the measurement problem, not requiring supranatural explanations like many worlds, non-locality or the denial of physical reality. The waves of complex numbers numbers described by Schroedingers equation are just statistical descriptions of an underlying reality we are not able to measure (yet).

"The cat cannot be both dead and alive at the same time . . ." Sweetheart Sabine obviously doesn't know my cat.

I was hoping to hear that Heisenberg’s dog was named curiosity.

sabine, Please do videos on Quantum Mech more frequently. you are just brilliant in explaining quantum in elegant way. a request by Indian Viewer

I was meaning to ask you to talk about Wigner's friend, but I'm glad it wasn't necessary!

Key word being “interpretation”.

In another universe, the Planet of the Cats call it Schrodinger's human.

Brilliant, thank you :)

When we lived in Copenhagen our cats found Schrödinger's Cat Experiments extremely cruel, but could not see any paradox. They explained it to us using another experiment. Sabine is penned up in a steel chamber, along with the following device (which must be secured against direct interference by Sabine): In a Geiger counter, there is a tiny bit of radioactive substance, so small, that perhaps in the course of the hour one of the atoms decays, but also, with equal probability, perhaps none; if it happens, the counter tube discharges and through a relay unlocks a cabinet with Schwarzwälder Kirschtorte. If one has left this entire system to itself for an hour, one would say that Sabine is still hungry, if meanwhile no atom has decayed. The first atomic decay would have unlocked the Schwarzwälder Kirschtorte and made Sabine happy. The geiger conter is the first instrument observing, the relay is the second, the lock is the third and Sabine is the first human observer. The psi-function of the entire system is irrelevant for this massive system (Sabine excluded of course).

at this point the cat starved to death. No one opened the box to feed him. .. 😥

I prefer the interpretation that says Schrödinger was just showing how silly the Copenhagen interpretation is.

Typo in chapter list: "7:12 Winger's Friend" should be *Wigner's*

In my opinion, the best demonstration of wavefunction concept applicable to a macroscopic system is superconductivity and Josephson's junction.

"Is it really both dead and alive ? And if so, what does that mean ?" Zombie Cat ! Open-shut-case Johnson !

Or is the cat always stressed, annoyed or fed up through being endlessly placed in the box by the minds of curious humans LOL. Funnily I remember in my youth trying to convince people that mirrors both reflect nearfield reality but the things outside of reflective viewing area were and could be completely different realities... beyond the room or reflection viewpoint....with interesting and amusing mixed results

Ditch determinism. With randomness available in a computer simulation we also have the Vernam cipher available to deal with spooky action at a distance. We need to add the randomness in a manner which respects the fact that the sort of behaviour associated with the violation of Bell's inequalities is strictly orthogonal to the behaviour associated with the Schroedinger equation.

Think of it this way. It is “rendering in real life.” Think of every turn of your head, light travels to your eyes differently (but just like you it takes the quickest way possible). So, it has to be in a constant state to accept light to reflect it back (superposition). Kinda of like little packets of information/data and when the information is read released back and the other is deleted (can’t be that position). So, when we measure it, the photon used is measuring which causes the collapse state.

Don't forget Schrödinger's Cat Litter : clean or not clean?

if schrödinger's cat is still alive, it's the oldest living cat i know :)

I'll have to watch again to understand why "spooky action at a distance", which is the quantum entanglement already proven, is possibly on the cutting room floor.

As for the question you ask at the end, my gut leans to 3 being false, 1 being probably true, and 2 being definitely true. That makes me think we need some outside the box questioning of 2, as that would be the place we would most likely be overlooking or misunderstanding something. It is hard to say without any formal background on the subject.