Schrodinger's Cat and Relativity: A Thought Experiment

I really did try and understand what you tried to say, but it was just way too cofusing. Is there an easier way to explain this to me?

reply to post by Astyanax


ah, i see. well what i read was that it begins its life as an unobserved subatomic particle called a photon, and when observed, changes to a visible wave. and the problem was trying to prove that such a change occured. thus schrodinger's cat thought experiment provided the answer that light is both a particle and a wave, but not both at the same time.

[edit on 7-7-2009 by undo]

reply to post by undo

That's funny.

I'll try to keep it as simple as possible.

1. Light behaves as if it was a stream of particles. It also behaves as if it were a wave of energy moving through space. It isn't just light that shows this dual nature, by the way; on a quantum scale, all matter and energy does.
   
   
2. Even a single photon behaves like a wave in certain circumstances. This is a paradox, since hard little bullet-like objects aren't supposed to have frequency and phase characteristics.
   
   
3. Quantum mechanics is an attempt to understand this paradox.
   
   
4. Schrödinger's thought-experiment is simply an illustration of quantum ambiguity. It does not explain anything; it's just an illustration on a real-life-size scale of the way things are thought to behave at quantum scales, at least according to the 'Copenhagen interpretation' of quantum mechanics.

The number of caveats and reservations in that last point should tell you rather a lot about how much human beings really understand the quantum world.

reply to post by Astyanax


so if it behaves as if it were a wave of energy moving thru space, why did you ask me what it was if you already knew? you arguing with yourself or what?
smart people's brains work in interesting ways.

here was the context of the comment in question

i said: observation of light, changed the light from particle to wave? if i'm remembering this correctly.

you said: Sorry, you're not. Light can be equally well described as a particle or a wave, but that doesn't mean it is either - I mean, what is a wave?

..

you're just having fun condescending to what you consider lesser life forms

[edit on 7-7-2009 by undo]

Originally posted by undo
so if it behaves as if it were a wave of energy moving thru space, why did you ask me what it was if you already knew? you arguing with yourself or what?

smart people's brains work in interesting ways.

Yes, they understand the difference between rhetorical questions and interrogatory ones.

Light can be equally well described as a particle or a wave, but that doesn't mean it is either - I mean, what is a wave?

...

I think you misunderstand. I was only pointing out that saying something is a wave doesn't explain very much about it. Which is not a deficiency in your knowlege so much as a deficiency in human understanding of what terms like 'matter', 'energy', 'particle' and 'wave' really mean.

you're just having fun condescending to what you consider lesser life forms

Would you have preferred it, then, if I had called you ignorant and stupid? I didn't - and not out of politeness, but because I honestly don't think you're stupid or ignorant. Physics is difficult, and quantum mechanics almost impossibly so. If you have not been formally educated in these subjects, there is no shame in being ignorant of them - though it does show a certain deficiency of judgement to speculate, in writing, concerning that of which one is unqualified to speak. Something I, for one, would never do.

As it happens, you're one of my favourite people on ATS - though I no more expect to convince you of that than you will ever convince me that the Observer Effect licenses beggars to ride wish-horses.

Yet, when we look in the box, we see the cat either alive or dead, not a mixture of alive and dead.

en.wikipedia.org...

so what's alive and what's dead? you define the parameters of the experiment then? i thought the idea was to explain why light can't be both a particle and a wave, simultaneously. that it either has to be one or the other. and observation is what changes its state. if it started out as a wave and observation changed it to a particle, wouldn't that mean we had theoretically snuffed out the light by observing it?





[edit on 7-7-2009 by undo]

Originally posted by undo
Yet, when we look in the box, we see the cat either alive or dead, not a mixture of alive and dead.

Yes.

so what's alive and what's dead?

The answers to those questions do not change because of quantum mechanics. Alive is alive. Dead is dead.

you define the parameters of the experiment then?

Schrödinger's Cat is just a way of illustrating the paradoxes of quantum mechanics. It isn't an experiment. Nothing is proved by opening the box and finding the cat either alive or dead.

i thought the idea was to explain why light can't be both a particle and a wave, simultaneously.

That's wrong, I'm afraid. Light is simultaneously a particle and a wave.

that it either has to be one or the other and observation is what changes its state.

No, this is completely incorrect.

if it started out as a wave and observation changed it to a particle, wouldn't that mean we had theoretically snuffed out the light by observing it?

No, I'm afraid this is far, far removed from the true meaning of wave-particle duality, the uncertainty principle or the observer effect. In fact, it has no connection at all.

Originally posted by Astyanax
Even a single photon behaves like a wave in certain circumstances. This is a paradox, since hard little bullet-like objects aren't supposed to have frequency and phase characteristics.

I think this is the most important part of the problem. Science is currently working on the assumption (and I don't mean this in the pejorative sense - it is working on this assumption because of a simple limitation in current technology, therefore the situation is forced upon us) that a photon is in fact what we deem it be be: a single, discrete and indivisible particle of light.

The problem is that we also observe it as a wave, which cannot be a discrete and indivisible entity, but is a continuous, analogous instance of energy that cannot be 'disconnected' in any absolute way from the rest of physical reality.

I.e. there are no 'gaps' in physical reality (at least from the materialist scientific perspective). This is because if there were any gaps, then those gaps would be non-physical, and therefore non-existential, thus have no properties whatsoever.

That which has no properties whatsoever cannot have the property of providing 'space' between objects. The paradox of infinite divisibility dictates that we can never prove that we have found a fundamental discrete particle because we can always cut it in half (regardless of whether our technology allows us to literally do so or not).

I think another big problem here is that the people who are always going on about 'observation changes the outcome', are making the mistake that observation means 'thought'. What needs to be made clear is that OBSERVATION is in practical terms a synonym of INTERACTION. You cannot observe without interacting because a physical process is required in both instances.

However, the inherent problem lies in the fact that it is simply impossible for us to prove that 'thought' is not the thing that is changing the outcome, because anything which we prove automatically requires thought, because that is the way we work as a species. I.e. even though the process of observation itself was mechanical, and did not require thought or sentience, we can still only view those mechanical observations using thought.

Originally posted by spartacus mills
That which has no properties whatsoever cannot have the property of providing 'space' between objects. The paradox of infinite divisibility dictates that we can never prove that we have found a fundamental discrete particle because we can always cut it in half (regardless of whether our technology allows us to literally do so or not).

But divisibility is not infinite. You cannot, for example, divide a photon into components. Even if you think in terms of string theory, a photon is just a single string with specific properties.

That said, I don't disagree with your statement of the problem, so long as it is the problem as it appears to a lay person. To a physicist, there is no problem: matter and energy appear as waves when you look at them with a wave detector, and particles when you look at them through a particle detector. Matter and energy themselves do not change; just our view of them.

I think another big problem here is that the people who are always going on about 'observation changes the outcome', are making the mistake that observation means 'thought'. What needs to be made clear is that OBSERVATION is in practical terms a synonym of INTERACTION. You cannot observe without interacting because a physical process is required in both instances.

Absolutely right.

However, the inherent problem lies in the fact that it is simply impossible for us to prove that 'thought' is not the thing that is changing the outcome.

On the contrary, it is very simple. All that is required is that the 'observer' correctly predict the outcome of the random quantum process he is observing (e.g. photon detected at slit A or B; cat in box dead or alive) significantly better than chance. As soon as you think of it in these terms you realize that it is impossible.

Quantum mechanics offers no support for belief in the paranormal, or for mind-over-matter theories, or for assuming that consciousness is the 'ground of all being'. Sadly, our spiritualized, macrobioticized, dekarmarized and ascended New Age pals will never understand enough physics to know why.

Correction

Originally posted by Astyanax
Inside Schrödinger's Catbox, however, there is a 50-50 chance that the cat is alive at the moment the box is opened.

This is wrong, of course. The probability varies depending on how long the cat has been inside the box. Apologies for posting misleading rubbish on ATs, something I'm forever berating others for doing.

Surprising none of you eager 'quantum physics' fans caught me on it.

Originally posted by Astyanax
But divisibility is not infinite. You cannot, for example, divide a photon into components. Even if you think in terms of string theory, a photon is just a single string with specific properties.

I think the point I was trying to make was that, just because the current limitations of our technology and understanding of physical theory don't allow us to divide these elements, it doesn't mean that it can't be done. Surely we should err on the side of caution and always be prepared to make the concession that we don't have the whole picture, and may indeed never have the whole picture?

Let us not forget what happened when atoms were first discovered. We thought we had discovered the fundamental and indivisible building blocks of reality, how wrong we were...

Obviously, infinite divisibility is theoretical, and possibly will never be provable (indeed, it seems axiomatic that this would be the case, since proving infinite divisibility would take forever!). But science uses theory all the time, so I don't see that there is any justification for saying that infinite divisibility does not exist in absolute terms.

I guess this kind of thing could only ever come down to a belief or faith that it does or doesn't exist. The problem this poses though, is that science itself is founded on the idea (at least, it was originally, probably less so now) that we don't need belief or faith, because it can show us what is 'true' in objective terms. However, the whole quantum theory thing calls objectivity into question. It doesn't disprove objectivity, but it shows that it may not be provable either.

Originally posted by Astyanax
On the contrary, it is very simple. All that is required is that the 'observer' correctly predict the outcome of the random quantum process he is observing (e.g. photon detected at slit A or B; cat in box dead or alive) significantly better than chance. As soon as you think of it in these terms you realize that it is impossible.

Sorry, I probably didn't make myself clear in my meaning here. When I spoke about thought, I didn't mean in the sense of some innate free will, i.e. "I want it to go through slit A, so I will make it so by the power of thought". What I meant is that thought is an inherent part of what we are, so even though thought may be a deterministic process and therefore we have no free will, this in itself does not disprove that it is thought itself that determines the outcome. I'm not saying I believe this to be the case, just that it is inherently not provable that it isn't.

reply to post by CaninE.G


Objects have exact values whether we can define them accurately or not. Bacasically, we are not some semi-divine observer of the universe and as such, there may be things that we do not know about and to an extreme, will not know about in relation to events we observe on an everyday basis.

My idea was to overlap two things that we couldn't mathmematically measure with any certainty: The life of an animal approaching death and distance in respect to an arbitrary midpoint. The kicker was that both factors simultaneously assumed values we couldn't accurately measure.

Then I hoped to show how despite three possible outcomes, only one would happen, only one did happen, and a third variable (the animals intial momentum) was the only real variable that would determine the outcome. Since the momentum only had one exact value and that value had only one exact cause, we could have predicted a 100% accurate outcome.

This implies that there is only one possible outcome to every event in the universe and that only that one event has any chance of happening. The "outside" force (as quantum physics calls its) acting on a system to bring about an event from a field of probabilities can be predicted to cause the event as it is connected with the initial system on a bigger level. Everything is connected and as such, everything that will happen in the future has exact set-up events occuring right now that will only bring about that future.

Our will isn't free, it is consequential of every other event occuring in the one big system that is the universe. If you could account for all these events, you would know what would happen in the future without fail. That is a big task and one that is more than likely far beyond the capabilites of a human or any significant group of lifeforms but that does not disqualify the idea that everything is connected despite our inability to observe and account for such things.

Nothing is proved by opening the box and finding the cat either alive or dead.

it's been a few years since i read the info on it and looking back over the subject i see where i made my mistake (et.al, observing causes the wave to collapse to a particle instead of the other way around, which doesn't make alot of sense, but whatever).

well i think what he was hoping to prove with it was that it has to be either alive or dead. he was ...i think...arguring against superposition (?) being a constant state.

also, if you'll notice my posts are riddle with ? and "i think" or "if i recall correctly", so please don't get wound too tight about my interest in the subject.

[edit on 9-7-2009 by undo]