Schrödinger's Cat

[Qfwfq]

An example of a question that arose elsewhere, whether or not QM breaks macroscopic determinism:

A (fully macroscopic) detector may trigger or not depending on single particles being emitted, and in the right direction, and even with the right values of some observables including spin (see Stern-Gerlach magnets). The QM formalism which predicts the emission will, as you might expect, predict a QM state and not necessarily determin said values with certainty....Can the detector's output be predicted? Is there determinism?

Is there determinism at the microscopic level, or what kind is there and isn't there?

 

How about at the macroscopic level?

[Decartes]

First I would like to say what a wonderful website. I have only just discovered it after looking for articles on General Relativity & Quantum Theory.

 

My view is that Schrödinger's Cat is just a thought experiment and you have to be very careful with such things in physics. I think as someone mentioned, If a person was in the box than he or she would observe their own demise or continued existence and this would be the same as looking in the box.

 

You need to look at the Copenhagen Interpretation and other interpretations.

 

Great stuff:)

[Tormod]

First I would like to say what a wonderful website. I have only just discovered it after looking for articles on General Relativity & Quantum Theory.

 

Thank you - and welcome to Hypography!

[lindagarrette]

First I would like to say what a wonderful website. I have only just discovered it after looking for articles on General Relativity & Quantum Theory.

 

My view is that Schrödinger's Cat is just a thought experiment and you have to be very careful with such things in physics. I think as someone mentioned, If a person was in the box than he or she would observe their own demise or continued existence and this would be the same as looking in the box.

 

You need to look at the Copenhagen Interpretation and other interpretations.

 

Great stuff:)

The idea is that in the quantum world, only probabilities are legitimate predictors. There are too many unknowns to be sure if an event will occur or not. Looking at it doesn't make it happen, it just validates that it did happen.

[Qfwfq]

Copenhagen Interpretation, an alternative name for Born's interpretation, is the very one according to which the cat would be a|dead> + b|alive> just before opening the box. Another interpretation is Bohm's but it isn't very accepted, it doesn't seem to fully solve the problems and is essentially a hidden variable type of view.

 

Welcome Descartes!

 

There are too many unknowns to be sure if an event will occur or not.

Hmmm... I'd say it's a bit more than complexity alone. There is the matter of constructive and destructive interference and many effects. Even in Bohm's view these must be accounted for, it considers the Schrödinger equation and also the guiding wave equation; it does not essentialy make different predictions, not about what can be observed.

 

Looking at it doesn't make it happen, it just validates that it did happen.

How about observing which slit the particle went through in the case of Young interference?

 

The riddle is: where is there a demarcation between the one and the other type of situation?

[Zohaar818]

Most people misunderstand what point Erwin Schrodinger was actually trying to make. His point was that the indeterminancy which is dominant at the quantum level (e.g. Heisenberg's Uncertainty Principle) does *not* translate well into the macroscopic world. That's not to say that quantum uncertainty does not have macroscopic effects, but that the observational issues really don't apply directly.

 

Cheers,

Buffy

 

This hypothetical experiment came about in order to illustrate Heisenberg's Uncertainty principle and of course everyone remembers Einstein's retort to Bohr that God did not play dice!

{*Einstein was very unhappy about this apparent randomness in nature. His views were summed up in his famous phrase, 'God does not play dice'. He seemed to have felt that the uncertainty was only provisional: but that there was an underlying reality, in which particles would have well defined positions and speeds, and would evolve according to deterministic laws, in the spirit of Laplace. This reality might be known to God, but the quantum nature of light would prevent us seeing it, except through a glass darkly. }

-Stephen Hawking

 

In my earnest opinion, both gentlemen were half-right. There is a lot of merit in the uncertainty principle...and in some quantum instances Bohr and the gang were absolutely correct in their assumptions. Having said that, Einstein might not have been wrong about the 'underlying reality'...

But what is the 'underlying reality'..is it God as the Creationists would have it..or some other ethereal force.

Frankly..and please forgive the chutspah of an absolute layman to venture such a theory..I think the best way of resolving the argument is to use the casino analogy...thin k about the universe just as you would a grand casino. In that casino are to be found many games at seperate tables, all conforming to their own unique rules of chance and probability.

 

Obviously the rules and probablilities of 'texas hold ém poker' are not the same as 5 card stud..even though they are both variations of 'poker'.and Blackjack, using the same cards has different rules still.

And of course poker is played at a different table than, say mah jong, or roulette..and how about craps? Now then..think about God..[a hypothetical..I am not preaching Deism, honest!] If the Universe is one big casino, what would that make God? Wouldn't he be casino owner!] Why play dice if you own the casino?

You design all these tables..dimensions...the parameters within which things can happen, factors can interact, according to set guidelines of probability..and although you may not be certain at any roll of the dice [or draw of the card, spin of the wheel..] what particular outcome will result..you can know over the extent of time that all results will fall within the

parameters of probability..'chance' as originally designed into the game.

That underpins, in part..the case for Intelligent Design. That although one single creator did not sit down and personally design each and every creature that ever came into existence, or solar system it inhabits, or the universe wherein it is to be found..there was an overall design.. abuilt in method to the madness..and an assurance that out of chaos would come eventual order.

 

Conversely..the universe may be, as the japanese believed..equivalent to a 'go' board in which all possibilities are infinite until the first and second stone have been placed, at which time the probabilities become more finite..that the game [universe] continues until there are no more stones to place and the outcome becomes all too predictable.

 

So maybe God does not play dice, but GO.

 

As for Schroedinger's Cat...I agree with the poster who called attention to the sentience of the cat and begged the question..wouldn't the cat also influence the outcome through observation?..[and we all know cats are good observers].

 

Each and every one of us is schroedinger's cat...we are observers affecting the experiment. In fact..we ARE the experiment...perhaps we have been designed to answer the question. how aware of its own mortality can any species be before it drives itself crazy and /or attempts to play God?

[paultrr]

On that last responce you started with something that made sence and then stumbled on into declaring that all of this backs up the ID camp. I would agree the universe is rather a casino. I would also agree that its possible there is some underlining order that governs everything. But nature itself tends to be orderly, at least on larger scales and I find it much more logical to assume that nature is the source and not some outside devinity or devinities. But then you drop back to saying something very true. We are all part of the experiment itself. We are in fact, when it comes to quantum theory, the cat stuck in that box. While I suspect that thought alone has little effect upon the outcome, since the bullet coming in is itself real by everything we define such by, I do suspect that we have this problem when it comes to seperating what condition one will be in after its all said and done. That aspect involves thought. Even if the outcome is we are dead and that thought is the last one we ever have.

[Agent-X]

:( The cat's dead man. DEAD I TELL YOU!!!!11 :(

 

;) :( :sun: :( :hyper:

[Zohaar818]

On that last responce you started with something that made sence and then stumbled on into declaring that all of this backs up the ID camp. I would agree the universe is rather a casino. I would also agree that its possible there is some underlining order that governs everything. But nature itself tends to be orderly, at least on larger scales and I find it much more logical to assume that nature is the source and not some outside devinity or devinities. But then you drop back to saying something very true. We are all part of the experiment itself. We are in fact, when it comes to quantum theory, the cat stuck in that box. While I suspect that thought alone has little effect upon the outcome, since the bullet coming in is itself real by everything we define such by, I do suspect that we have this problem when it comes to seperating what condition one will be in after its all said and done. That aspect involves thought. Even if the outcome is we are dead and that thought is the last one we ever have.

 

Dear Paultrr,

 

Thanks for responding. Glad you found my post to have a point or two in its favor. Having said that..please do not mistake me for an ID-er. Although sympathetic to some of their claims of evidence contravening the standard models [especially in the archeological and fossil record] I have ZERO tolerance for their dogmas, and am rather strongly opposed to their claiming the Bible to be the literal or inspired word of God..yada yada.

The best [and worst] that could be said of my 'religious' affiliation is that I think of myself as a spiritual person.

A religious person being someone afraid of going to hell...whereas spiritual individuals tend to be those who have already been there.

May the force be with you...

 

Zohaar

[Qfwfq]

Frankly..and please forgive

A bit of chutzpah is the kind of thing I was hoping for! :( Thank's for the bit of imagination... :(

[aurumdeus]

If a person was in the box than he or she would observe their own demise or continued existence and this would be the same as looking in the box.

 

this is true, but then that person's situation would still have different possibilities for anyone who was not inside the box. for example, the person within would know if they were dead or alive, but to anyone else they could still be in either of those states. the same goes for the cat. it knows if it is dead or alive, but to us outside it is still in a superposition of these states.

[paultrr]

Dear Paultrr,

 

Thanks for responding. Glad you found my post to have a point or two in its favor. Having said that..please do not mistake me for an ID-er. Although sympathetic to some of their claims of evidence contravening the standard models [especially in the archeological and fossil record] I have ZERO tolerance for their dogmas, and am rather strongly opposed to their claiming the Bible to be the literal or inspired word of God..yada yada.

The best [and worst] that could be said of my 'religious' affiliation is that I think of myself as a spiritual person.

A religious person being someone afraid of going to hell...whereas spiritual individuals tend to be those who have already been there.

May the force be with you...

 

Zohaar

 

I was not sure to begin with. I also like that hell and even heaven is here on earth approach myself.

[Qfwfq]

I never got around to posing a key question here.

Most people misunderstand what point Erwin Schrodinger was actually trying to make. His point was that the indeterminancy which is dominant at the quantum level (e.g. Heisenberg's Uncertainty Principle) does *not* translate well into the macroscopic world. That's not to say that quantum uncertainty does not have macroscopic effects, but that the observational issues really don't apply directly.

Where is the line to be drawn? Where do these "observational issues" cease to be directly applicable?

[infamous]

I never got around to posing a key question here.

Where is the line to be drawn? Where do these "observational issues" cease to be directly applicable?

 

At the quantum level things get vey fuzzy, sort of analogous to the melting point of plastics. The definition of a plastic is a material that has not distinct melting point, unlike a metal which melts at a precise temperture, plastics have no precise melting temperture. At the quantum level, things also get not so precisely defined. One aspect of this phenomenom results from the energy induced by the very action of observation. Some energy will be transfered to the object of study which makes exact calculations effectively impossible.

[Qfwfq]

So, are you saying that the QM formalism itself, with Heisenberg's uncertainty, is the reason why the QM formalism and Heisenberg's uncertainty "gradually" ceases to apply?

 

Hmmm, I don't quite buy that!

 

Plastics, like glass, are not true solids but liquids having a viscosity that becomes extremely high in a certain range of low temperatures. This can certainly be explained by studying the molecules involved in terms of QM and solid state Physics and so on, but the metaphor doesn't seem to clear the matter up.

 

The experimental setup is such that, according to the QM formalism, the detector should be in a linear superposition between having or not having triggered and this would give rise to the cat being in a state like:

 

a |alive> + b |dead>

 

Buffy noted that this wouldn't really be so because the QM formalism doesn't apply macroscopicaly, but without giving a reason. Any ideas?

[infamous]

So, are you saying that the QM formalism itself, with Heisenberg's uncertainty, is the reason why the QM formalism and Heisenberg's uncertainty "gradually" ceases to apply?

?

What I'm saying is this: No matter how far removed from the object of experiment, the experiment will itself influence the final data. Not to mention the fact that even without the scrutiny of experiment, quantum theory suggests that we can never precisely know the time and position of effects.

[Qfwfq]

The argument still appears circular...