can someone explain shrodingers cat (sorry if the spellings wrong)?

Question

I have sort of had this explained to me once before, but its still hard to get my head around it.
How does this relate to other stuff as well (in the same vein)?

Answer 1

In quantum mechanics, it is possible for a particle's state to be a super-position of two very different states. For example, when you measure the spin of an electron, it will always turn out to be spin up or spin down. However, before you make the measurement, it is possible that the electron's state is a combination of the UP state and the DOWN state. For example, you might have:

Electron = 1/sqrt(2){ UP + DOWN }

In this situation, if you measured the electron's spin, 50% of the time, the measurement would come out spin UP.

The idea that a particle could be in a super-position of two totally contradictory states struck some physicists as odd. As a test of this idea, physicists proposed the following thought experiment:

Put a cat in a box. Construct the box so that, if a certain atom decays, a poisonous gas will be released in the box which will kill the cat. Imagine that the atom has a 50% chance of decaying in a period of 10 minutes. After 10 minutes, what is the wave function of the cat before we open the box?

Quantum mechanics seems to tell us that the cat's wave function is the following superposition of alive and dead states:

Cat = 1/sqrt(2){ Alive + Dead }

Most people would agree that the idea that a cat could be, in any sense, simultaneously alive and dead is absurd. So what's going on?

The mistake we made was believing that the wave function of the atom only collapsed when a human being stepped in to observe the cat (and thereby observe whether or not the atom decayed). In fact, the atom's interaction with the macroscopic system of the killing box constituted a measurement. So, while we don't know whether the cat is dead or alive before we look, it certainly is either dead or alive, and not a combination of both.

Answer 2

Erwin Schrodinger proposed a gedankenexperiment (that's one that you run in your head, not on the lab bench) in which a cat is enclosed in a box, along with an infernal device containing a radioactive source, a radiation detector, and a vial of poison. The box is closed up for an hour, during which time the source has a 50/50 chance of emitting a radiation that will trigger the detector and kill the cat. An hour passes, and you are about to open the box. Is the cat alive, dead, or something in between? This all has to do with something called superposition of wave functions; there is one function for the cat alive, and another for the cat dead.

Answer 3

It is an analogy used to explain an aspect of quantum physics. The theory is that particles such as electrons are in an indeterminate state until they are observed, just as a cat in a box can't be determined to be alive or dead until you open the box. Shroedinger was the one to come up with the analogy.