A bit of help please!
Someone out there must have read, understood and inwardly digested all the Schroedinger's Cat stuff about quantum physics and alternative dimensions/universes.

Can anyone outline it in really simple terms for me please?

I'm writing a short story which is using the whole theory of many worlds/parallel universes and I want a bit more background on how it might (or does) work.

I'm aware of quarks(?) vibrating in two places simultaneously - hence the cat being both dead and alive.

I'd like the whole thing explained again so hopefully it'll trigger off another plot development.

Ta.
( chickenlady b3ta's very own Elizabeth Taylor, Mon 18 Aug 2008, 10:13, 16 replies, latest was 16 years ago)

Schroedinger's cat isn't really about parallel universes
it basically says that until something (a tiny particle etc.) is measured then it exists in all quantum states. it's called quantum superposition. i.e. the cat is both alive and dead until you open the box.

my understanding of the alternate universes thing is that essentially any time anything happens there is another universe where it didn't happen, or where something else happened.

what level this happens on is debatable, but seeing as we (humans) are pretty insignificant, it's not going to be based on something as fiction-friendly as when we make a life changing decision a la sliding doors.
( Vipros. clever got me this far, then tricky got me in, Mon 18 Aug 2008, 10:24, Reply)

But then surely that's just chance?
There is a 50% chance it will be dead and a 50% chance that it's alive.

Why is it linked to so many theories of multiple universes and the many worlds thing? I'm sure Stephen Hawking has mentioned this too.

Educate me!

:)
( chickenlady b3ta's very own Elizabeth Taylor, Mon 18 Aug 2008, 10:26, Reply)

I think that it would normally be thought of as chance
but because the state of the cat is dependant on the release of a radiactive particle by a source it gets all quantum :-)
( Vipros. clever got me this far, then tricky got me in, Mon 18 Aug 2008, 10:29, Reply)

hmm, I guess it does link into the many universes thing
but only in that everything does

the state of the cat is dependant on this release of a particle. essentially, if the many universes thing is to be believed, in one universe it has been released and cat is dead, in one it hasn't and it is alive

but until you open the box you don't know, so the cat is theoretically both alive and dead.

it's not about the probability of it being alive and dead that tends to cloud the issue.

as I mentioned earlier, it is trying to prove the point that regardless of the chance of something, until you measure it (i.e. look in the box) it exists in all states (cat is alive and dead)

en.wikipedia.org/wiki/Quantum_suicide

this is an interesting take on it, and I think could make a good story
( Vipros. clever got me this far, then tricky got me in, Mon 18 Aug 2008, 10:31, Reply)

I can offer....
the Sliders boxset......
( TGB checking Off Topic is still shit at, Mon 18 Aug 2008, 10:35, Reply)

Sliders?
I missed that one....maybe I'll find a torrent...once I've written this, otherwise I'll end up using their ideas.

You have no idea how irritating it is to write something and then realise, shit, that's straight from Dr Who or Philip Pullman!
( chickenlady b3ta's very own Elizabeth Taylor, Mon 18 Aug 2008, 10:43, Reply)

Vipros!
That Wiki article is just what I want!

I haven't read all of it yet, but just the line about conscious beings being immortal!

FANTASTIC!

I can hear the neurons firing in my head already.

Thank you!
( chickenlady b3ta's very own Elizabeth Taylor, Mon 18 Aug 2008, 10:45, Reply)

@Chickenlady
From someone who has had to redraft serveral short stories after helpful friends have gone "hey didn't that happen in *tv show/film* I do know it is very annoying :(

Sliders was basically about this guy who discovers how to go between parallel worlds and how small changes in history effect the world. The first two series were really good then it started getting a bit off. :)

Edit: The start of the article reminds me of that Jet Li(?) film "The One"
( TGB checking Off Topic is still shit at, Mon 18 Aug 2008, 10:48, Reply)

read
the unadulterated cat, Pratchett describes it in almost understandable terms
(Halfy By light alone, Mon 18 Aug 2008, 11:00, Reply)

Schrodinger Quotes
en.wikiquote.org/wiki/Erwin_Schr%C3%B6dinger
(Eds Meds Mathskillz=1,Socialskillz=0, Mon 18 Aug 2008, 11:02, Reply)

So,
You have a cat in a box, with a 50% chance that said cat is alive or dead.

In classical physics (and, indeed, common sense), the cat is either alive or dead.

In quantum physics, because you cannot know whether the cat is alive or dead, the cat exists in a "superposition of states" - that is to say, it is simultaneously alive and dead.

Where quantum and classical physics agree is in saying that you cannot know the state of the cat until you look inside the box. Where quantum differs is that it recognises the effect of the observer on the system, i.e., the effect of you opening the box to look at the cat. In doing so, you are interfering with the system. But until you interfere with the system, its state is not determined.

So, this leads us back to your question about alternative dimensions. What happens at the instant you open the box? The two most popular / widely accepted suggestions are:
(i) aka 'The Copenhagen interpretation' - the cat exists as a fuzzy cloud of quantum uncertainty, in which it is simultaneously alive and dead, until the box is opened, and these two states 'collapse' into one state, either a live or dead cat.

(ii) aka the 'Many Worlds interpretation' - the cat again exists in its superposition of live and dead states, but when the box is opened, the universe diverges into two separate paths: a universe in which the cat is alive, and a universe in which it is dead.

Does that help or, indeed, make any sense?

I think it was Niels Bohr who aptly stated that "Anyone who is not shocked by quantum mechanics has not understood it."
(LongJohnBaldry, Mon 18 Aug 2008, 11:03, Reply)

Here's my limited understanding of the matter.
Quantum mechanics suggests that the characteristics of a particle are indeterminate. As Vipros points out, this can be understood in terms of superposition. This superposition is resolved only upon observation. (Same sort of thing can be said for the collapse of a quantum wave-function.)

Shroedinger was not the only person not to like this - Einstein was another. The cat example was intended as a reductio ad absurdum - if the superposition account is true, then the cat is both alive and dead until you look. But this cannot be the case. Therefore, modus tollens, the interpretation must be wrong: quantum indeterminacy is intolerable. (EDIT: of course, if you accept indeterminacy as a principle, you won't have any problem with the cat.)

The many-worlds interpretation suggests that there is a separate universe for each possible quantum state, and that, with each observation, we simply identify which possible universe we are in.

And that's about all I know on the matter. And I might not even know it - I'm more than likely to be wrong.

Meh.

I'll go away now.

BTW - Chickenlady - I've challenged you to a Scrabulous game...
( Enzyme is powered by sunlight, Mon 18 Aug 2008, 11:08, Reply)

One other thing...
Have you read Mobius Dick by Andrew Crumney? (I think that's his name.) It's on this sort of thing; he's a proper theoretical physicist, and not a bad novelist. Bastard.
( Enzyme is powered by sunlight, Mon 18 Aug 2008, 11:12, Reply)

*reads above replies*

*wonders whether or not he is alive or dead*

*goes for lie down*

Edit: If I have a really good cognitive process on the interference of wave mechanics and their place in the universe(s), would that be:

A super superposition position supposition?

or not?
( Pooflake braces for an onslaught..., Mon 18 Aug 2008, 11:16, Reply)

Mobius Dick
That sounds like a very promising book...either it's got to be about a large whale swimming around in a never-ending loop or else the average Chav male constantly trying to pull....



Thanks to everyone for the explanations. I'm now a bit more educated! Yay!

How much of this actually makes it to the story is another thing - I'm also toying with the idea of it just being all in someone's head - it's far, far easier to just write psychosis than physics...well, it is for me...

*EDIT* I have accepted your scrabulous challenge Enzyme...prepare to have your butt well and truly kicked ;)
( chickenlady b3ta's very own Elizabeth Taylor, Mon 18 Aug 2008, 11:17, Reply)

Could also have a look at this...
www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2008/08/13/scispooky113.xml&CMP=ILC-mostviewedbox
(Bicycle Repairman "you're also a bit of a wanker", Mon 18 Aug 2008, 13:33, Reply)