Schrodinger's Cat vs. The Principle of Explosion

[Crazymechanic]

Thanks dauto but I'm already relaxed , the only time I got a little " amazed" was when you said that rephrasing let' s throw out anything else than just a few numbers. :D

Well actually it' s not so much of a disagreement here as I just didn' t understand you from the beginning but now I think I do.
Yes the atom indeed cannot know what it's going to turn out upon measurement just as you can only have a slight prediction about how your children will turn out before you have them or how your wife will turn out before you marry her.So yes an atom before a measurement is somehow a half complete set.

The thing you referred to that you don't understand was meant about if we could make a superpositioned cat then upon measurement would it be a cat anymore because if we speak about the fact that an atom takes a certain state upon measurement then if we could do this to a whole animal the question then becomes not so much alive or dead but would it still be a cat ?
See what i mean?

 

[dauto]

I understand it better now though I don't see why wouldn't it be a cat. A dead cat is still a cat, I assume, and so is a live cat. A superposition of both is probably still a cat. But now we are really talking about philosophy, I think.

 

[USeptim]

The point of the paradox is to indicate the opposite. There is a state called superposition which is neither this nor that for a quantum system. If such were not the case, Bell tests would yield different experimental results. (As well as many other things.)

What it's more ashtonishing from Bell's test is that Alice and Bob spins remain oposite after the collapse, because in some way the collapse of A affects on B instantaneouslly. This is well described on Wikipedia.

http://en.wikipedia.org/wiki/Bell's_inequality

Anyway, this means that we have a mixed state between two particles but I cannot see clearly that this is the same that having just one particle in two states, as the cat paradox tells.

 

[dauto]

The particle really isn't in two states. It is in a single well defined state that happens to be a superposition of two other single well defined states.

 

[Crazymechanic]

well yes the ca can be only dead or alive when we are speaking about one atom decaying due to whatever makes it decay.
What I meant was a whole cat (every atom in a cat) put on superposition like that quantum experiment where they put many atoms in such a state.
Now when you measure all those atoms they turn out various different ways (states) and you cannot predict with certainty the outcome , that why I asked will it then be a cat anymore ?

 

[dauto]

I can't see any reason for it not to be a cat anymore.

 

[bhobba]

As I understand the question, this thread is not supposed to be about interpretations of Quantum Mechanics. It is about whether quantum mechanics states that the cat might in principle (forget about the inpracticality of creating a macroscopic superposition for a moment) be alive and not alive at the same time,

The point is the answer to that is interpretation dependent.

According to the Copenhagen interpretation prevalent at the time the thought experiment was proposed there is no issue - the cat is alive or dead at the time the box is opened - or even if it is not opened.

What Schrodinger's Cat does is highlight an issue with Copenhagen's assumption of a classical world that measurements appear in. The same with the Ensemble interpretation that Einstein held to - but that was very much a minority interpretation at the time. Not that Einstein would have minded in the least - it was simply further evidence for his view QM was incomplete.

The explosion theorem? Never heard of that one. Even did an internet search and it drew a blank.

Thanks
Bill

 

[D H]

The explosion theorem? Never heard of that one. Even did an internet search and it drew a blank.

It's rule #1 in logic: Contradictions cannot exist. Aka the law of non-contradiction. The reason is that if a logical system allows even one single contradiction, a statement that is both true and false, then every statement can be proven to be simultaneously both true and false. Ex falso sequitur quodlibet: From falsehood anything follows, aka the "principle of explosion."

Do an internet search on principle of explosion.

 

[bhobba]

It's rule #1 in logic: Contradictions cannot exist.

My background is in applied math - its used all the time in proving theorems. You assume something and show it leads to a contradiction. Sometimes its the only way to prove something, but even if it isn't it quite often is the easiest.

Despite the fact I personally have used it many many times, and read textbooks that use it with gay abandon, I have never heard it given any kind of name or formal title. You learn something new every day.

Thanks
Bill

 

[Maui]

You misunderstand me. I'm not denying Quantum Mechanics. I'm explaining it. The answer must be no because the explosion theorem unleashes all sorts on inconsistencies. But alas Quantum Mechanics does not trigger the explosion theorem, despite appearance.

Actually, it is required by theory and experiment that all objects, incl.the cat, be in superposition. The tricky part is why we observe either a dead or alive cat and as I stated a bit earlier the most consistent interpretations on this are the MWI and the CI (or some combination of the two), by far the most popular interpretations out there. There would have been a conflict and an explosion of inconsistencies if we observed superpositions but we do not. We only observe classical stuff. It's been proven in multiple experiemnts in the last decade that this is exactly the case for all objects tested - from pieces of metal to currents flowing in superconducting rings. You just have to remove the special condions that we as observers are finding ourselves in and voila - you learn a lot of ground breaking stuff about how the world works.

 

[D H]

That's quite enough. I have closed this thread. This thread started on a bad footing, talking about philosophy, and now it is threatening to devolve into yet another "my interpretation of QM is better than yours" kind of thread.

Report this post (click on the report button) if you don't like that I closed this thread and want it re-opened. Your complaints will *not* be taken against you. (That's assuming the report isn't laden with expletives. We will take that against you.) I'll start the process by reporting this post myself.