"To come up with a more tangible example of just how odd this view of reality is, Erwin Schrödinger devised a thought experiment in 1935 starring a cat that is neither dead nor alive."

No, no he didn't - he came up with that "thought experiment" to show the absurdity of the whole "events have and have not happened simultaneously until observed" part of quantum physics. It was a joke, not an explanation, not an experiment, a joke.

Read "How the hippies saved Physics" - fun book.

Oh for FSM's sake, just toss the cat into the microwave and be done with it!

A can of tuna will work fine. Open the can. If the cat jumps up and looks expectantly for some tuna, it is alive. If it just lays there, it is dead

I am beginning to understand why I didn't do well in physics (40 years ago)

LittleSmitty: A can of tuna will work fine. Open the can. If the cat jumps up and looks expectantly for some tuna, it is alive. If it just lays there, it is dead

What if he just has no sense of smell and is restin'?

Maybe he's pinin' for the fjords?

They shoulda asked Maru the Car. He knows ALL about this box business

Cat.

Damnit.

LittleSmitty: A can of tuna will work fine. Open the can. If the cat jumps up and looks expectantly for some tuna, it is alive. If it just lays there, it is dead

same thing as opening the box.... The point of this gedankenexperiment was just to show the absurdity of the copenhagen interpretation when it comes to everyday experience. But let's face it, the mathematical aspects of a QM calculation, and QM as a whole except in rare situations, has pretty much nothing to do w/ everyday experience.

if you're an electron, you care. if you are larger, you don't. The mathematical tools are phrased as wave functions for the system's state that "collapse" to specific values when operated on by a Hamiltonian or whatever. The cat's wave function is psi = sqrt(2)*alive + sqrt(2)*dead. That is, by construction, the complete description of the cat. Can't be anything else. Open the box and one one of the two states is measured, not both. Can't be anything else.

/csb

LittleSmitty: A can of tuna will work fine.

A can of anything, heck, just walk thru by kitchen.
/my guys are hogs.

Cut off its head and count the rings

dnrtfa:

I work in a pizzaria in a strip mall next to a chinese food restaurant. Due to some emergency or another, they closed down for about a week and opened back up yesterday. Now, this chinese restaurant is absolutely farkin horribly nasty in their kitchen, and there's always a little kid runnin around outside. So one day right before they closed for a week, the kid was out back playing with 4 or 5 kittens while I was out back smoking. No big deal, whatever. While they were closed for whatever emergency they had, though, my boss was outside cleaning up around the back of their shop cause she was just tired of looking at it I guess. She flipped the lid off a five gallon bucket and found 4 or 5 dead kittens in the bucket. Were these cats dead or alive before she flipped the lid off?

/Not a CSB
//But sadly true.

Just to be nit picky;

wjllope: The cat's wave function is psi = alive/sqrt(2)+ dead/sqrt(2).

Unless your cat has 9 lives, in which case it might look more like 3*alive/sqrt(10) + dead/sqrt(10)

\slow day at work today

You know I actually got a 30 day ban (I think, might have been less) for the free cat picture a couple years back. Saying some mumbo jumbo about posting animal gore or something. Then again I was a real douchey troll back then and none of the admins liked me.

Flt209er: Unless your cat has 9 lives, in which case it might look more like 3*alive/sqrt(10) + dead/sqrt(10)

ahhh, yes, the Many Worlds Lives Interpretation.... good point.

This is progress, but why does it still incorporate the concept of wave function collapse at all? Wave functions don't collapse, they evolve continuously, according to the mathematics.

Let's face it, the whole Copenhagen interpretation is a historical accident. The pioneers of QM, feeling their way one contradictory result at a time, could just about get their models of a handful of particles to make the right predictions (look how long it took to figure out why there are two electrons in the innermost shell or to correctly model any atom more complicated than hydrogen...).

So once they had a reasonable idea of what happens in a very carefully isolated and preserved quantum system; and they knew that on macroscopic scales everything appeared to be classical; and they had no idea how one became the other; they took the pragmatic attitude that there were so many fundamental things still to be understood at the quantum scale that the in-between should be left for later when they had better tools, both experimental and mathematical.

And then somehow, in the intervening decades, an attitude of "don't know, don't care" became entrenched as an orthodoxy of "don't ask, don't tell".

/Many Worlds is even worse, before anybody starts. It has exactly the same problem as Copenhagen in that it still fails to define what an "observation" is, and then throws an infinity of universes on top to distract people from the problem.

Remember kids:

The whole cat in a box thing is a metaphor for particles. It does not apply to macro objects like cats. Just because you haven't opened the box doesn't mean that the cat is undead. The cat is either dead, or alive. Your ignorance of the cat's condition has zero influence on the cat. It's megalomania to think that the cat needs your permission to be alive or dead.

Solipsism, while good for brain fapping, is useless. If we can't awaken from the matrix, the matrix is reality in every way that matters to its inhabitant(s).

apeiron242: The whole cat in a box thing is a metaphor for the mathematical formalism QM uses to describe particles, and the result of an "experiment" that mathematically is a sort of projection onto some Hamiltonian.

/but yeah - you're right. I said the same thing above... cheers

Oh gaddammit. DontMakeMeComeBackThere: "To come up with a more tangible example of just how odd this view of reality is, Erwin Schrödinger devised a thought experiment in 1935 starring a cat that is neither dead nor alive."

No, no he didn't - he came up with that "thought experiment" to show the absurdity of the whole "events have and have not happened simultaneously until observed" part of quantum physics. It was a joke, not an explanation, not an experiment, a joke.

Read "How the hippies saved Physics" - fun book.

Exactly. Only one state is real, you just don't know which it is until you look. But nothing changes except for what you know. That cat is alive or dead independent of your observation.

nocturn: Exactly. Only one state is real, you just don't know which it is until you look. But nothing changes except for what you know. That cat is alive or dead independent of your observation.

Not exactly. For a quantum system, all the states are real -- a particle such as an electron really can be in a superposition of states. You can "look" at in such a way that you can know it's in a superposition of states, provided you do it in a way that doesn't reveal which state it's in. Superposition has even been demonstrated for macroscopic systems such as a SQUID (although not yet a squid).

The question Schrodinger was asking was this: We don't yet know why it is that an electron really can be both "up" and "down", but a cat is always really "alive" or "dead". The mathematics doesn't describe anything corresponding to an "observation" or "instantaneous" collapse. Doesn't anybody else think we ought to worry about that?

And the answer that came back from the dominant personalities that made up the Copenhagen group was this: Not yet. The formalism works well for everything we know how to test for the time being. Once we understand some of these fundamental problems better, we'll come back to how classical appearances arise from quantum reality.

And then somehow, over the course of the 20th century, the popular presentation of that conversation has degraded to:

Schrodinger: Look how wacky quantum mechanics is!
Copenhagen: Shut up and calculate.

greenz: You know I actually got a 30 day ban (I think, might have been less) for the free cat picture a couple years back. Saying some mumbo jumbo about posting animal gore or something. Then again I was a real douchey troll back then and none of the admins liked me.

Well, a few hours ago they greenlit an image of a dead cougar (in a box, no less!), so maybe today's freebie day.