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[Bebpo]

I'm trying to read about Schroedinger's Cat on various sites but since I never took any science classes in school I know nothing of quantum mechanics and am having trouble understanding the idea of things existing on a wavelength until we look at where it is.

I mean if the vial breaks and the cat is poisoned then I would think that the cat is dead regardless of whether the box is opened. I'm confused about the whole existing in a state of dead and alive.

Can anyone explain this stuff in simple terms?

 

[xsarien]

You still need to confirm the cat's death, until you do, as far as the fun fun world of quantum is concerned, the cat is neither dead nor alive until you observe the result.

It's kinda funky shit, and using something as direct as a cat and a vial of poison isn't the best way to demonstrate the principle, but it's used because it at least gets the point across.

 

[rareside]

I love Schroedinger's Cat. It's one of the few things I remember from my college physics education :lol

 

[Dilbert]

I mean if the vial breaks and the cat is poisoned then I would think that the cat is dead regardless of whether the box is opened. I'm confused about the whole existing in a state of dead and alive.

The point of Schröedinger's cat is that the cat is NOT in a superposition state -- it is clearly either alive or dead long before you open the box. It is a gedanken ("thought experiment") designed to pose the following question: What constitutes a "measurement" with respect to quantum mechanical systems?

We have no problem describing, say, electron spin as an equally probable superposition of +1/2 or -1/2, or -- in the case of the cat -- a 50% probability of beta emission. When "measured," though, it has only one definite value, and it will retain that value for as long as the "measurement" persists. "Macroscopic" objects, however, do not have superposition states. Although each individual atom or molecule may have some uncertainty associated with it, the chance of ALL of them having their uncertainties in the same direction is virtually impossible.

I've put the words in quotes which are at the heart of the matter (no pun intended): How "big" does something have to be to enter the realm of "macroscopic?" And what exactly constitutes a "measurement?" Is it the beta particle triggering the Geiger counter and therefore the poison gas? Is it the human consciousness which observes the opened box? Is it a change of state in some subatomic particle which causes the beta particle to be emitted in the first place? Is it God? (The last point of view was Bishop Berkeley's...the guy who wrote the philosophical dialogue which was the origin of the (misquoted) "tree falling in the forest" question.)

 

[nitewulf]

The point of Schröedinger's cat is that the cat is NOT in a superposition state -- it is clearly either alive or dead long before you open the box.

that is pretty much the gist of it. heisenberg's cat example confuses ppl because they start thinking how can the cat be dead and alive at the same time. but it's just a thought experiment, and is either clearly dead or alive. there is no "superposition".
since the cat itself is such a large object, in comparison to an electron, quantum mechanics does not apply to it.

 

[Teal'c]

There was a neat thing on PBS about a year or so ago about String Theory and its tie in of Quantum and Newtonian forces. Its still assuming a lot of things but it's still interesting. Maybe someday this Cat riddle will seem elementary and we'll look back at how stupid we were.

 

[Dilbert]

There was a young man who said, "God,
Must think it exceedingly odd
If he finds that this tree
Continues to be
When there's no one about in the Quad."

REPLY:
"Dear Sir: Your astonishment's odd:
I am always about in the Quad.
And that's why the tree
Continues to be,
Since observed by, Yours faithfully, God."

:lol :lol :lol

That's awesome -- who wrote it?

 

[WHOAguitarninja]

There was a neat thing on PBS about a year or so ago about String Theory and its tie in of Quantum and Newtonian forces. Its still assuming a lot of things but it's still interesting. Maybe someday this Cat riddle will seem elementary and we'll look back at how stupid we were.

Intersting point of note, my electricity and magnetism professor was on that show (Jim Gates). Great teacher...really really hard class though. Mid term is friday, last time he taught it the average was 30%, hahaha (though he curves it enormously).

 

[way more]

All is explained in this ancient verse.



Schroedinger, Erwin! Professor of physics!
Wrote daring equations! Confounded his critics!
Win saw that the theory that Newton'd invented
By Einstein's discov'ries had been badly dented.
What now? wailed his colleagues. Said Erwin, "Don't panic,
No grease monkey I, but a quantum mechanic.
Consider electrons. Now, these teeny articles
Are sometimes like waves, and then sometimes like particles.
If that's not confusing, the nuclear dance
Of electrons and suchlike is governed by chance!
No sweat, though--my theory permits us to judge
Where some of 'em is and the rest of 'em was."
Not everyone bought this. It threatened to wreck
The comforting linkage of cause and effect.
E'en Einstein had doubts, and so Schroedinger tried
To tell him what quantum mechanics implied.
Said Win to Al, "Brother, suppose we've a cat,
And inside a tube we have put that cat at--
Along with a solitaire deck and some Fritos,
A bottle of Night Train, a couple mosquitoes
(Or something else rhyming) and, oh, if you got 'em,
One vial prussic acid, one decaying ottom
Or atom--whatever--but when it emits,
A trigger device blasts the vial into bits
Which snuffs our poor kitty. The odds of this crime
Are 50 to 50 per hour each time.
The cylinder's sealed. The hour's passed away. Is
Our pussy still purring--or pushing up daisies?
Now, you'd say the cat either lives or it don't
But quantum mechanics is stubborn and won't.
Statistically speaking, the cat (goes the joke),
Is half a cat breathing and half a cat croaked.
To some this may seem a ridiculous split,
But quantum mechanics must answer, "Tough @#&!
We may not know much, but one thing's fo' sho':
There's things in the cosmos that we cannot know.
Shine light on electrons--you'll cause them to swerve.
The act of observing disturbs the observed--
Which ruins your test. But then if there's no testing
To see if a particle's moving or resting
Why try to conjecture? Pure useless endeavor!
We know probability--certainty, never.'
The effect of this notion? I very much fear
'Twill make doubtful all things that were formerly clear.
Till soon the cat doctors will say in reports,
"We've just flipped a coin and we've learned he's a corpse."'
So saith Herr Erwin. Quoth Albert, "You're nuts.
God doesn't play dice with the universe, putz.
I'll prove it!" he said, and the Lord knows he tried--
In vain--until fin'ly he more or less died.
Win spoke at the funeral: "Listen, dear friends,
Sweet Al was my buddy. I must make amends.
Though he doubted my theory, I'll say of this saint:
Ten-to-one he's in heaven--but five bucks says he ain't."

 

[Loki]

:lol

Hah, that's excellent.

 

[ohamsie]

Heh, these limericks are so appropriate, what with St. Patrick's Day just around the corner.