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Schrödinger cat

ragus
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Posted 08/12/08 - 06:07 AM: Subject: Schrödinger cat	#1
There's something I don't understand about the Schrödinger cat experiment. The starting point is a live cat. When, where and how does the cat go into a superposition of states? In what ways would the superposed cat be different from a live cat?
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abba
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Posted 08/12/08 - 06:26 AM:	#2
Link - - - Google is your friend.

ragus
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Posted 08/12/08 - 08:38 AM:	#3
Thanks abba but where in the link is the answer to my questions?
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Makarismos
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Posted 08/12/08 - 08:44 AM:	#4
The cat is between life and death from the moment it cannot be observed by a human, as the result only collapses upon observation. .. This really makes me wonder why a human must be involved: why is the cats observation of itself not good enough to determine if it is alive or not??? The experiment was meant to highlight the problems of a particular model of QM, so perhaps that is another one of the absurdities in the thought experiment? If the cats observation is not enough, then why do all unobserved cats not work just as well for this thought experiment? Many universes all the way.

Cadrache
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Posted 08/12/08 - 10:30 AM:	#5
From a simplified viewpoint, it is essentially a claim of illogic. Something akin to the "If a tree falls in a forest, does it make a sound?" Science requires proof for existence of any state. Since there is no way to determine if the cat is alive, then the proof is not there. Since there is no way to tell that the cat is dead, the proof is not there. Since proff is based as a True / False entity, then you end up in the both are possible, or not possible area. One of the largest error in Schrodinger's experiment, is that nobody seems to question whether or not the Cat exists to begin with (once inside the box); existence/non-existence being a part of possible states of an object.

ragus
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Posted 08/12/08 - 01:05 PM:	#6
Makirismos wrote The cat is between life and death from the moment it cannot be observed by a human, as the result only collapses upon observation. Even if Schrodinger forgot to put the radioactive element into the box? Cadrache wrote Since there is no way to determine if the cat is alive, then the proof is not there. Since there is no way to tell that the cat is dead, the proof is not there. Since proff is based as a True / False entity, then you end up in the both are possible, or not possible area. Are you saying that the live cat becomes alive/dead from the moment we can't observe it? What if there was a video running in the box which we couldn't look at for some time? We would know what the cat had looked like after we opened the box. Would that spoil the experiment?
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Makarismos
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Posted 08/12/08 - 01:22 PM:	#7
ragus wrote: Even if Schrodinger forgot to put the radioactive element into the box? Well, perhaps. I think that it is important that the radioactive element must have the possibility of decaying, triggering the release of the toxic chemical, and kill the cat - because it is this that brings the quantum event in to the macro world. However I am not so sure we need this. Surely the cat may be killed by some other process, equally triggered by a quantum event? So long as we are not observing it, the cat will be in a state of flux. If it is correct that we need to observe the result in order to collapse the waveform - something I think is false, mainly due to this thought experiment. This was in fact the purpose of the thought experiment. ragus wrote: Are you saying that the live cat becomes alive/dead from the moment we can’t observe it? What if there was a video running in the box which we couldn't look at for some time? We would know what the cat had looked like after we opened the box. Would that spoil the experiment? My take on this would be that yes, if we believe that a quantum events outcome is an uncollapsed waveform until the moment of observation causes it to collapse - then it would remain uncollapsed until we observe it. Once we observe the result (watch the video) the waveform collapses - at that moment - and we see the cat die of poison gas. The past is effected by our observation in the present. Like I said, many worlds all the way,

Cadrache
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Posted 08/12/08 - 01:42 PM:	#8
I don't technically adhere to that train of thought actually. Is the back of your head alive or dead? The idea of Shrodinger's cat merely states that because we cannot prove it, we cannot state which it is. See Wittgenstein's Tautology. Use of the video camera would and would not spoil the experiment. Technically, the claim is that we would not know what the outcome is while the experiment is going on. Whether or not the cat is alive, dead or other can only be found out after the experiment has been done. (ie. open the box) The uniqueness of the theorum is that all it claims is that as the experiment is happening, we cannot know the current state of the cat. This includes whether or not there is a camera in the box. Note that if the camera had a live feed while the experiment was going on, then the experiment would not be shrodinger's experiment, due to the fact that external observation is being taken while the experiment is happening.

Crow
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Posted 08/12/08 - 05:00 PM:	#9
Schrodinger's cat was created to reveal the 'measurement problem" in Bohr's quantum physics. It is held that the probability wave function collapses when a measurement is taken. But if quantum physics is taken to be the comprehensive physics (and classical physics just being an approximate subset of quantum physics), then all phenomena must be quantum in nature. So, when a measurement is taken, the measuring device itself must be quantum in nature and itself be a superposition of possible states (thus the superposition of an alive and dead cat). Even more troubling, if the physical structure of the observer and his brain are as described by quantum physics, then the observer must also be in a quantum superposition of possible observations. If there is nothing which is not a quantum phenomenon, then how could collapse ever be invoked? The Many-Worlds theorists say there is no collapse, just a branching of each possibility into a seperate universe time line. Others say consciousness is 'special' and can cause collapse, but no mechanism is given. The "measurement problem" is still not settled, and Schrodinger's kitty-cat is still discussed.
The only thing I know for sure is that I don't know.

swstephe
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Posted 08/12/08 - 05:46 PM:	#10
A photon acts like a particle if you measure it like a particle and it is like a wave when you measure it like a wave. So how do you treat it if you want the best of both worlds? Half particle and half wave. So the illustration is to treat a cat as 50% dead and 50% alive after one hour with a randomly activated time bomb. The cat's perspective is irrelevant because if its dead, it wouldn't be able to observe that fact. My weirder version of the illustration is ... you get a cat from the pet shop. You don't know if it is male or female until you examine it more closely, so a QM physicist ought to treat it like a hermaphrodite cat. "What have you don't to the cat? It looks half dead" -- Shroedinger's wife.
Ethics is the measuring of morality. Morality is the measuring of good. Good is the measuring of benefit. Benefit is the measure of values.

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