
#1
Sep1307, 04:51 AM

P: 235

I just learn the cat in a box paradox, where we cannot know whether the cat is dead or alive until we open the box, so the cat is in a superposition between life and death. yup, got it!
I am about to learn quantum physics. And I think it would be really good if I got a grasp of it first. So this cat thing, is analogy for particle, and its life, is for particle's properties. So far so good. What I don't understand is that if we don't know the particle state, then I would assume that the particle state is irrelevant as it won't affect anything, because when it affect something, we know its state, in other words, the box had been opened. Thus would it really matter what the particle state is before the box is opened? 



#2
Sep1307, 05:01 AM

Sci Advisor
P: 4,491

Basically, there are two schools of thoughts.
1. Until you look, the cat is neither dead nor alive. 2. It is allways either dead or alive even if you do not look. But in this case, a sort of nonlocal communication between physical objects is possible. At the moment, nobody knows with certainty which view is the correct one. 



#3
Sep1307, 05:29 AM

P: 981

Or:
3. When you look, the world splits in 2, one for the possibility that it's alive, and one for it's dead. 4. Whether it's dead or alive only exists in your head, and so it's a trivial truism that it's neither dead or alive until you look. Any interaction where you learn more about the cat is going to have an effect on the cat, because you're a clumsy physicist and all you can do is a deliver a wellaimed poke. 5. ... There's probably countless others. In practise, it doesn't matter: you model the problem in the language of quantum mechanics, follow the procedure, and you will be able to calculate the probability that the cat is alive or dead, without ever wondering about what exactly happened in between. It says a lot that experimentalists never worry about the measurement problem but the theorists do all the time. 



#4
Sep1307, 05:43 AM

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P: 28,776

cat in a box paradoxIf it is #1 or #2, then you would never have bondingantibonding in chemistry, and no coherence energy gap in the Delft/Stony Brook experiments. I certainly haven't seen any one formulating any physics using #1 and #2 to derive what have been observed. Zz. 



#5
Sep1307, 06:16 AM

Sci Advisor
PF Gold
P: 2,196

Someone should perhaps point out that the "cat in a box" is a higly idealized gedanken experiment. A real cat would always be EITHER dead or alive inside the box, regardless if you open it or not.
The reason is that any object the size of a real cat is an open quantum system meaning it couples to the enviroment. Hence, it can never be in a superposition of dead/alive for very long (its "wavefunction" will decay extremely fast). This is the reason why it is so difficult to e.g. build good quantum bits out of macroscopic objects; they interact with the enviroment (or, more specifically, enviromental degrees of freedom) and decay very quickly leading to short coherence times. 



#7
Sep1307, 06:36 AM

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P: 4,491





#8
Sep1307, 06:44 AM

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P: 28,776

My interpretation isn't something I invented. The Leggett paper that I've highlighted before many times on here regarding the measurement problem clearly stated this position. When you have a state being described as a linear sum of orthogonal states, then the obvious interpretation here is that ALL of those states exists at the same time. If not, then the Schrodinger Cat paradox isn't anything unusual. The cat is either dead or alive, which isn't new nor strange. Why would Schrodinger go to all that trouble illustrating something that is not unusual? Zz. 



#9
Sep1307, 07:37 AM

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P: 4,491





#11
Sep1307, 07:53 AM

P: 20

Man, you guys are crazy.




#12
Sep1307, 07:58 AM

P: 981





#13
Sep1307, 08:05 AM

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P: 4,491

Of course, as a Bohmian, I prefer 2. Still, I believe that I am able to speak consistently about 1. as well. 



#14
Sep1307, 08:13 AM

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P: 28,776

#3 The cat is BOTH dead AND alive is identical to #1 The cat is neither dead nor alive? 2. When you toss a coin but don't look at the outcome, do you say that it is (i) either head OR tail, or (ii) head AND tail? Zz. 



#15
Sep1307, 08:25 AM

Sci Advisor
P: 4,491

b) I say it is in the superposition of head and tail (recall that I am still talking within the 1. paradigm, despite the fact that I actually prefer 2.) By the way, this is my 666th post. 



#16
Sep1307, 08:32 AM

P: 981

Guys ... come on! We're arguing over words, not meaning! We invented mathematics to make words less slippery! Dany and ZapperZ: I think you already understand each other, and agree that you use the same words in different meanings; as far as who's "correct", I say it doesn't matter.




#18
Sep1307, 08:56 AM

Sci Advisor
HW Helper
P: 2,886




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