[cheryl j (OP)]

The other day I goggled Schrodinger's Cat experiment to try to find out if anyone had actually tried it. Wikipedia said that it has been tried successfully with photons, beryllium atoms, and a piezoletric tuning fork (whatever that is) but it didn't say if it was actually tried with a cat or something larger than atoms or what the results were. Does anyone on the physics forum know the answer, or what in your opinion would the results be? In physics, when something is not in a "definite state", is it really in both states at once or could it just flip back and forth between the two? And do you really believe observation or knowing makes a difference, because that just freaks me out.

[CPT ArkAngel]

According to Quantum Mechanics, you simply can't measure at the same time a superposition of states of a single particle. So no it can't be proved. But the probability of the wave function has been validated by these experiments. Anyone who says the contrary does not understand QM. The superposition of states is only one interpretation among many. It seems to be the one favoured my most physicists. I am 99.9999999% sure that it is not true. I think this is a ridiculous interpretation. A lack of imagination and a lack of will to look for a better explanation, a true causal interpretation that makes sense...

[Pmb]

In physics, when something is not in a "definite state", is it really in both states at once or could it just flip back and forth between the two? And do you really believe observation or knowing makes a difference, because that just freaks me out.

No. A system is always in a definite quantum state. That state might be an eigenstate of an observable. In this case there are only two valid eigenstates: |cat is dead[/i]> and |cat is alive>. What is almost always omitted is that the initial state is not a superposition of the two states, i.e. |lifestate of cat> = A|cat is dead> + B|cat is alive>. However that is not true. The initial state is |cat is alive> because we always put a living  cat into the box. When the box is closed and the experiment is set into motion by allowing the system to kill the cat is not kill the cat then the system is in the state |lifestate of cat> which evolves with time. The longer the cat is allowed to be in that state the greater the chance of it being killed. If the poison is allowed to act only over a period of time such that the probability of releasing the poison is 50/50 and then stopped from killing the cat then the state of the cat is in either the state of alive or dead. All of this is illustrated at http://en.wikipedia.org/wiki/Schrodinger's_cat which talks about the various interpretations of the experiment. One interpretation is that the cat always knows when it is alive or dead. However nothing changes the state of the system when someone looks into the box to see if it's alive. This is because the cat is not a quantum system but a macroscopic system. Looking at the cat does not change the system that is |lifestate of cat>.

There is a book which contains a complete description about all of this called Quantum Paradoxes by Aharonov and Rohrlich. You can download a copy of this at http://bookos.org/. See chapter 9 Quantum Cats. I haven't read it yet but it seems quite thorough.

[jeffreyH]

This thought experiment is simply to illustrate a point, very badly.

[yor_on]

Sweet question Cheryl.

Seems as if it is math that describes this universe best. Looking at quantum logic, it's when you get 'coagulates' this math turns 'predictable'. I guess I would ask JP to describe, when a word for something, consisting of infinities, turn to practically defining a 'finite result' macroscopically. Most of the science we use practically, as building a house, takes this for being certain.

[flr]

I guess nobody know for sure why quantum mechanics math works. This is why we have so many interpretations of QM.

 In the ensemble interpretation of QM  the problem of cat paradox is trivial.

[evan_au]

The Schroedinger's cat paradox was an attempt to highlight one of the counterintuitive results of the quantum world by extrapolating it into the macroscopic world where it doesn't really apply.

The quantum effects where the experiment does apply are fairly simple systems like an electron or an atom, which, when measured, may have one of two spin states, "up" or "down". You really don't know which state the electron is in until you measure it. And the electron does not record a history that tells you when it got into that state.

The wild extrapolation from an electron to a cat suggests that a cat has just two states, "alive" and "dead". However, these are both very complex states, and there is a somewhat blurry line between alive and dead (some would suggest that we begin to die as soon as we are alive). Unlike the electron, the cat does record an implicit history, so when you open the cat box, you can get a rough idea of how long the cat has been dead (or equivalently, how long it lived before it died).

[evan_au]

The familiar macroscopic world is dominated by entropy, which always increases over time (unless you expend energy). Eg a cat.
On a small enough scale, an isolated quantum system is not affected by entropy in the same way. Eg an electron in an isolated atom.
Entropy is the statistical behaviour of a large number of microscopic systems; the quantum behaviour is unfamiliar to us as macroscopic creatures, hence the paradox.

[AndroidNeox]

The cat box would have to be perfectly information-proof... not a bit of information relating to the cat's state could pass from the box or the indeterminacy of state would 'collapse' to a single state. So far, we have no way to create such a box.

[AndroidNeox]

I have solved the problem of Schrödinger's catbox!

Every physicist knows the problem of Schrödinger's cat. Where to get a reliable supply of cats? Or, for the nambi-pambi animal rights left wingnuts, to end the brutality?

Did you know that the Schrödinger phenomenon leads to a 50% fatality rate among cats? Well, I have designed the product that will replace the Schrödinger Catbox. I call it the Felix Coinbox.

It really works!

This small box contains one coin. Close the bit-proof cover, shake the box, open the cover, and the box presents a perfectly 50/50 chance for delivering heads/tails. Built with the same information-tight construction that Schrödinger used in his catboxes. Bellcurve Laboratories have determined with absolute certainty that these definitely maintain indeterminacy for any indefinite period.

Physicists no longer need to purchase large numbers of cats. The coin is reusable and certified for at least 100,000 uses. An amazing savings in cats and poison, not to mention cleaning and disposal fees, and at only a fraction of the price.

And, if you buy the Felix Coin-box Professional Edition, you can enable a second, independent variable (color). Amaze your friends by demonstrating Bell's Inequality. Disclaimer, to use the Bell Inequality feature you need a second coinbox to link to via the encrypted IR link, purchased separately.

[Pmb]

cheryl j - The reason I responded as I did was because it'd be illegal to do so and unethical as well and if it had been done nobody would admit to it and as such what'd be the point of doing it anyway? What would the results be if done?

[Pmb]

cheryl j - The reason I responded as I did was because it'd be illegal to do so and unethical as well and if it had been done nobody would admit to it and as such what'd be the point of doing it anyway? What would the results be if done?

I should add on to this that nothing useful would be learned by doing such an experiment. The cat is not a quantum mechanical object. Schrodinger thought that the interpretation of the cat as being a linear superposition of being dead and alive as being nonsense. A macroscopic object being a linear combination of two states is absurd. An electron can be in a linear combination of up and down spins, but a cat simply cannot be in a linear combination of alive and dead.

There was really never anything to be gained by running such an experiment. We'd only observe the classical results that we're all quite familiar with.