# Question regarding Schrodinger's Cat (Sorry If I Spelled it wrong)

1. Apr 11, 2012

### Ima_Fraud

I was doing some research for school and I was thinking of he Schrodinger's Cat Experiment. Can someone explain it to me. Sorry if I sound Amateur because I am.

2. Apr 11, 2012

### Mark M

Well, that's essentially the same thing as posting "Explain to me all of quantum mechanics." It's rather difficult to get into one, simple, answer, but I'll see.

In quantum mechanics, a particle can never have definite properties. For example, in the familiar world, something may be here, or it may be there. In quantum mechanics, however, since particles cannot have definite properties, such as positions, an electron can be here and there, simultaneously.

This egienstate, or superposition, as it is called, represents a blur of different possibilities. In time, however, it grows like a wave, spreading it's possible location even thinner. This makes up what is called a probability wave, or more precisely, a wavefunction. Wavefunctions evolve through time in accordance with the Schrodinger equation.

When you interact with a wavefunction, you trigger a collapse - the rapid decoherance of a wavefunction back to just a few possibilities.

So, now with that background, I'll explain Schrodinger's cat. Imagine we placed a decaying atom in a box for a half an hour. Since it is equally probable it will decay or not decay, it is in a superposition of decayed and not decayed. Let's now say this was hooked up to a measuring device, which upon measuring decay, will use a hammer to smash a vile of poison, killing a cat in the box. The box is left closed, so no external factors will trigger collapse. Now, since the atom is in a superposition of decayed and not decayed, we can deduce the cat is in a superposition of dead AND alive.

Hence, we end up with a cat that is in a superposition of dead and alive. Depending on different interpretations, however, this is interpreted in different ways.

If you're interested, here is an English translation of Erwin Schrodinger's original paper on the though experiment.

http://www.tu-harburg.de/rzt/rzt/it/QM/cat.html

Hope I helped, and welcome to the forum!

Last edited: Apr 11, 2012
3. Apr 12, 2012

### batabek

just pray for the cat and forget the rest :=)

4. Apr 12, 2012

### Ima_Fraud

Thank you Mark. I now understand.

5. Apr 13, 2012

### EileenSchuh

re spelling: to get that special Ö character in Schrödinger's Cat hold down alt key and type 0162.
The cat's dilemma has more to do with the dual nature of quanta--subatomic particles. Some experiments prove they are particles and other prove they aren't--that they are wave functions. Scientists believe it is the experiments themselves and the resultant observations of these particles, that causes them to be one thing or the other. Schrodinger said that didn't make sense...that quanta had to have a single true identity. Otherwise, if say an electron was shot a box that was triggered to kill a cat inside it if the electron was a particle and to leave it alive if it turned out to be a wave function what would happen to the cat until someone opened the box to "observe" which of its dual natures the quanta had expressed when it hit the trigger?
Then along came Everitt and his Many Worlds Theory...you can read all about that part of the story here http://eileenschuh.blogspot.ca/2010/07/whos-schrodingers-cat.html

6. Apr 13, 2012

### Mark M

Schrodinger and the rest of the Copenhagen Interpreters didn't say the particle had to have a definite property - they simply stated that even though particles do indeed exist in superpositions, it is nonsense to speak of them. To CI, all that matters is what happens after collapse.

7. Apr 13, 2012

### EileenSchuh

"...all that matters is what happens after collapse..."

Unless, of course, you're the cat... Which was the point of Schrödinger's thought experiment. While physicists can go merrily on their way believing in the dual nature of quanta and the role of observation in defining which of those natures is being expressed at any given moment in space and time...reality requires something more substantial than just agreeing not to speak about the nonsensical fallout of that belief. Otherwise...is that darn cat alive or dead until someone observes it?