Schrodinger's cat

[Chimera]

Could someone please explain, in idiot terms, what this means? I know it's supposed to be about superposition and quantum something, but I just don't understand what they're getting at.

[Will]

Could someone please explain, in idiot terms, what this means? I know it's supposed to be about superposition and quantum something, but I just don't understand what they're getting at.

Superpositions: subatomic particles behave in odd ways, ways that are often counter intuitive. This is best characterized by superposition, or the idea that a subatomic particle that is not measured or observed is actually in all possible states at the same time. When it's measured, the outcome goes down to one possibility. When it's not measured and only the effects are recorded after, the outcome is different.

The cat scenario is meant to illustrate the state in which the behavior of the particle is not measured vs. measured. When the cat is in the box, and the lethal trigger is triggered by the behavior of superpositions, the cat is both dead and alive, representing that the particle is in all possible states.

[Perillux]

Second time I have to type this... don't know why it didn't work the first time....

Schrodinger actually made this thought experiment to disprove his idea and show how ridiculus it is.  However, it backfired on him and now people use it to teach this concept.

Anyways. let me first explain (again lol) what a half-life is, if you already know you can skip this:
A half-life is an amount of time which is different for every radioactive substance.
Say you have a certain amount of atoms of a radioactive substance.  After 1 half-life  half of the atoms of that substance have decayed.  So for a single atom, after 1 half-life  that atom has a 50-50% chance of having decayed or not.  So until we measure it, it has a superposition of being decayed and not decayed.
NOTE: after the second half-life the atom does NOT have a 100% chance of decaying, it is still 50-50%.  It will always be 50-50% until it does decay.  Providing that we take measurements after each half-life.

Ok, so his thought experiment goes like this.  A cat, a radioactive atom, a geiger counter, and a vile of poison are placed into a box and sealed.
After 1 half-life of the atom there is now a superposition because the atom either decayed or it didn't (we don't know).
So, if the atom decayed the geiger counter will detect it and release the vile of poison killing the cat.
If it didn't decay the cat is still alive.
Which corresponds to a superposition of the cat being alive and dead.  Don't get too hung up over the alive AND dead thing.  It  is just a way of talking about superpositions of the wavefuntion.  Basically it means that the cat will be either alive or dead when we open the box, and in this situation has a 50-50% chance either way.
The weird thing is though, that the cat knows for sure if he is alive or dead because to him the wavefunction has collapsed.  But to us the wavefunction has not collapsed so he is alive and dead in a superposition.
We cannot know until we "open the box" or physically measure it somehow.

ok, now we can talk about what it really means for the cat to be alive AND dead.  So, by now you might be saying, well that all seems very obvious, we can't tell if the cat is alive or dead until we open the box, but the cat knows.. duh.
But, when it's in the superposition you cannot say, "it's in a superposition of alive and dead, but obviously it is either definitely alive, or definitely dead", which is a false saying.  I said you can think of an alive AND dead cat as an alive OR dead cat WHEN WE OPEN THE BOX (or in other words a cat that WILL be definitely alive or definitely dead when we open the box)  But while the box is closed it is alive AND dead.  NOT hypothetically, or mathematically alive and dead, but physically alive and dead.
That's why this experiment offers great insight into what we really know, and what is real, and is also the fundamental concept behind entanglement.

Hope that helps.

[curiosityandthecat]

Quantum superposition and electron entanglement from What the Bleep Do We Know?

[youtube:onb2vqq5]http://www.youtube.com/watch?v=qlomn1Hc_VM[/youtube:onb2vqq5]

And, like they said above, the cat (without being "measured" or checked-up on) is at both alive and dead. Here's an illustration:



 

[Perillux]

Thank you for posting that video.  It got me watching the entire series of them on youtube now.  Good stuff.

[Will]

 

That's fantastic! Schrodinger's LOLcat!

[Asmodean]

I have a couple more schroedinger's lolcats. Not as good as that one, but still useful... Somewhat.  

[Chimera]

What made me ask about this today was a LOLcat I saw on icanhascheezburger.com:

[joeactor]

Like the video - pretty good explaination.

(and the LoLCats too ;-)

So, based on how difficult it seems to be for normal humans to conceptualize these concepts, here are three possibilities that come to mind:

1) We don't know what we're talking about (ie. we don't have a full understanding of what's happening)

2) We are unable to understand it (ie. it is beyond our 3-dimentional, meat-based computer)

3) The "observer" model is just plain wrong even though it predicts well (think the fudged "crystal sphere" models and calculations)

Just some musings... nothing serious - carry on!,
JoeActor

[Asmodean]

"Good morning Dr. Schrödinger! I'm ho-ome! You did remember to feed the c... HEY WTF?!?!  

[Tanker]

To put in very simple terms, there are 3 Quantum states yes and no (think binary code ie: 1s and 0s) and mabey". If a subject is unobserved (shrodinger's cat) we can't tell if it lives (yes)or if it's dead (no). So until we look in the box and find out it, remains the third state (mabey) Basicaly Shrodinger is using his cat as an single example for what state everything is in before observance . We don't have any really obvious examples of the "mabey" quantum state since as we observe the world around us it's state has been decided.

This of course Isen't exact, but it's about as lay as I can make it.

[Perillux]

Tanker, do you read Scientific American?
Because the latest issue talks about how they could make quantum computers that use trapped ions in superposition.  So they have quantum states 1, 0, and "maybe".
Just wonering if you read it cause your response was similar.

[Jolly Sapper]

"Schrodinger's in ur base, super positioning ur kitty!"  

I like Tanker's explanation, it worked for my physics deprived mind.