What does a cat in a box have to do with quantum mechanics?

[beansbaxter]

"Schroedinger's Cat" was an example provided by physicist Erwin Schroedinger to demonstrate the absurd lengths to which some physicists would go to describe everything in the universe in terms of quantum physics.

Quoting directly from "The Present Situation In Quantum Mechanics":

"One can even set up quite ridiculous cases. A cat is penned up in a steel chamber, along with the following device (which must be secured against direct interference by the cat): 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 releases a hammer which shatters a small flask of hydrocyanic acid. If one has left this entire system to itself for an hour, one would say that the cat still lives if meanwhile no atom has decayed. The psi-function of the entire system would express this by having in it the living and dead cat (pardon the expression) mixed or smeared out in equal parts."

 

[CTho9305]

What don't you understand? It's a principle of quantum mechanics that a system is in all possible states until it is observed. The cat is both alive and dead, until you open the box.

Something I've wondered is, is it REALLY in all states, or is it in one state and you just don't know? Are they mathematically different?

I know in comp sci, you'll see the use of "Oracles", or things that always tell you what's going to happen, but if you think about it, you can see that the oracle is just a convenient way of saying "you tried every possibility". For example, in an NFA (non deterministic finite automat__), an oracle tells you which state to move to next. Of course, in an actual implementation, you just go to all the states and see if you reach an accept/reject state.

 

[axnff]

Something else you have to remember is that science (outside of mathematics) really has nothing to do with facts, per se. It is about modeling. If your model permits you make accurate predictions, then it is considered a truism, a theory. Whether it is *right* or not is neither here nor there.

It doesn't matter if [particle|cat|significant other] is *actually* in all states, or one state, or even no state until observed; that is simply how the model works. And it works...

 

[jagec]

Man, that reminds me of a GREAT photoshopped poster that said "Schroedinger's cat: If you don't know, you're not supposed to."

Really, the concept is just a way of thinking about it. It's not so much that the system truly occupies every single state, it's just that you have no way of knowing until you measure, so it's foolish to try and pretend. The cat is either alive or dead, but you don't know until you open the box, so from YOUR standpoint it's a bit of both.

 

[Psych]

It's simple in terms of quantum mechanics as long as you don't think about it TOO much. When a particle needs to choose a path and the chance is exactly 50/50, and it must choose a path, it goes one way and another particle takes the path not taken.

When they combine again at a certain point, one gives way to the other. The cat is in a proverbial state of limbo because it won't die until the box is opened, but the chance is 50/50, so it's all about the path not taken, which is either life or death.

By the way, can anyone refresh my memory as to if the path not taken particle is detectable?

 

[beansbaxter]

The first post was more of an FYI; I found it very interesting and just wanted to share it.

On another note though, please explain to me in layman's term the Einstein-Rosen bridge as it relates to black hole and white holes?

 

[DrPizza]

Originally posted by: beansbaxter
The first post was more of an FYI; I found it very interesting and just wanted to share it.

On another note though, please explain to me in layman's term the Einstein-Rosen bridge as it relates to black hole and white holes?

What is this? An attempt to ask seemingly random scientific questions to see who among us can answer most clearly in layman's terms? Are you looking for a writer/editor for scientific periodical aimed at the general public?

Anyway, from what I understand, the Einstein-Rosen bridge refers to the mathematical prediction of shortened distance from one point in the universe to another point in the universe, or to another universe. As it relates to white holes, the mathematical computations are simpler as a white hole is a singularity with no mass. (Given the age of the universe, it is highly doubtful if any white holes would exist now, had there even been any white holes ever.)
The popular name for the Einstein-Rosen bridge is a wormhole. I think that one concept is "matter goes into a black hole and out of a white hole," but I'm not sure if that isn't just fiction as I don't know much about white holes. But, I think that matter can't exist in a white hole to pop out into the universe, thus that concept seems wrong.
IIRC, Einstein and Rosen weren't using the computations to predict wormholes, but rather to explain something about electrons.(?)

 

[beansbaxter]

Originally posted by: DrPizza

On another note though, please explain to me in layman's term the Einstein-Rosen bridge as it relates to black hole and white holes?

What is this? An attempt to ask seemingly random scientific questions to see who among us can answer most clearly in layman's terms? Are you looking for a writer/editor for scientific periodical aimed at the general public?

Nope. Actually, I happened to hear the "einstein-rosen bridge" thing on Alias the other night so I thought I'd bring it up.

 

[bobsmith1492]

I'm sorry, Ockham's Razor killed Schroedinger's cat

 

[f95toli]

Shroedingers cat was a toy and I guess at the time was thought of as a philosopical problem.
There were also strange ideas relating to "observers" and so on.
Today it is a well-understood phenomena which is often used in applications. Quantum computer, Quantum teleportation and quantum cryptograhy are all based on this.

The system does in fact exist in all states at ones until decoherence forces it to decay into a single state. Today there are many experiments where you can measure the decoherence time.

Schroedingers cat is no mystery anumore, it is still strange but we understand it quite well.

And, by the way, a real cat could never exist in a superposition for very long, the dechoerence time for something as big as a cat is extremely short since it is impossible to shut down the interaction with the enviroment. So in a practical experiment the cat would therefore either be dead or alive.
Note though that this is a PRACTIAL problem, if we somehow would manage to insulat the cat it would work.

 

[beansbaxter]

Originally posted by: axnff
Something else you have to remember is that science (outside of mathematics) really has nothing to do with facts, per se. It is about modeling. If your model permits you make accurate predictions, then it is considered a truism, a theory. Whether it is *right* or not is neither here nor there.

very good point and a good thing to always keep in mind. this is of course one of the truths that allows the scientist to accept the possibility of an existence. basically, "anything is possible".