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March 19, 2007

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Actually, I did come up with a way to determine whether or not consciousness is necessary through a relatively simple experiment; I just don't have the clout to get it performed. The trick is to run the double-slit experiment, and have a detector on each slit that, when turned on, will tell us which hole the electron (or whatever) passes through. It's known from prior experiments that if we don't use a detector, we'll see the classic interference pattern, but if we do use it, we'll see the sum of two diffraction patterns from the two slits.

Now, here's the trick: What if we turn the detector on, but don't look at what it's telling us? We can stop the flow of information immediately before any conscious observer knows anything about which hole the electron went through. Hell, we could dump the data as soon as it's collected to be on the safe side. This way, we know that if we see an interference pattern, then consciousness (or something else in a step we blocked off) is what causes the collapse. If we don't see an interference pattern, then we can rule out consciousness as causing the collapse.

I tried running this experiment by my Quantum Professor, but he refused to act on it as he was already sure that consciousness was the key ingredient. I have to see if I can find someone who's unsure and who'll listen to me.

Two links I give aspiring Quantum Quakers:

Quantum Quackery

Schrödinger's Zombie

a detector on each slit that, when turned on, will tell us which hole the electron (or whatever) passes through.

You can't, I'm afraid, infophile. I believe that when cunning experiments have been performed to constrain an given electron to a single slit, it goes through both of them. I don't pretend to "grok" it, but I guess nobody does.

Actually, when you set up a detector, you do indeed force the wavefunction to collapse at the slits, so if you only shoot out one electron at a time, you'll find it at only one of the slits. And then, after it passes through, you'll see the classical sum of two diffraction patterns.

This is the first stop in YesBut’s tour of blog land. I arrived here by entering the key words “proves nothing” in Google Blog Search.

The blog certainly gave me something to think about, but now I must move on using the keyword chosen at random from your blog: “irrational”. If you want to know where that takes me check my blog http://grumpyandfarting.blogspot.com on Tuesday 2oth March

Infophile,

Would that experiment really do it? People could always argue that whatever means you sued to store the measurement was actually in a supersposition of states and that you need to observe that for one of those states to be "chosen", much like the cat itself.

So, in these terms, at least, the Copenhagen Interpretation is unfalsifiable.

However, I have the feeling that something like what you suggested has been and it gave non-woo results...

Wouldn't the cat itself be an observer in this instance? What if it were two cats in the box, or a person and a cat?

Well, presumably the person and/or second cat would be equally affected by the poison. But the point is that the system inside the box is closed off from the outside, so there is no transfer of information between them. Until a measurement occurs, in which information (photons, noise, the smell of rotting cat) is transmitted from the system inside the box to a measurement device outside the box (a monitor, an eye, a person's nose), then the system inside the box is in a superposition state, from the point of view of the measure-er.

Great post!

it's actually an interesting read to see what theists have to say about quantum mechanics. Take it from me, someone with an obsessive interest - but no formal training - in Quantum mechanics, that all of what Alex is saying is twaddle.

http://www.vision.net.au/~apaterson/esoteric/esoteric_theory.htm

Why wouldn't a recording device in the box with the cat replayed at a later time be sufficient to prove or disprove the indeterminacy of its state?

Moreover, why isn't this the cat thought experiment obviously understood as a reductio? What exists that is not specifically what it is, e.g. either dead or alive? Why conflate lack of measurement with metaphysical indeterminacy?

Why wouldn't a recording device in the box with the cat replayed at a later time be sufficient to prove or disprove the indeterminacy of its state?
Because the state is only indeterminate as long as there is no net transfer of information from the system to its surroundings (i.e., from the box to the outside world). Once you pull the recording device out, there has been a transfer of information, and the system collapses. As long as the recording device is inside the box, it is part of the system; it is the system which is in a superposition state.

I think a lot of people get hung up on the cat in this experiment; all the cat is is a recording device, a tool for measurement. The activating of the poison and the death of the cat are both just ways to measure whether or not the isotope has decayed. It makes no difference if you have this Rube Goldbergian cat-killing device or just a simple sensor to tell whether or not the isotope has decayed. It's the system which is in a superposition state, and any such system would remain in that state until there were a net information transfer between it and its surroundings.

I think.

Moreover, why isn't this the cat thought experiment obviously understood as a reductio? What exists that is not specifically what it is, e.g. either dead or alive? Why conflate lack of measurement with metaphysical indeterminacy?
And this is where some of the quantum weirdness comes in, specifically with regard to wavefunction collapse and superposition states. It's not metaphysical in the least, it's simply counterintuitive. Before we make a measurement (a transfer of info from system to surroundings), the system could be in two states, for which there is equal probability. While we have this uncertainty (not Heisenbergian uncertainty, mind you), the system is in a superposition of two states, simultaneously occupying both and neither. When the measurement is made, the wavefunction of the system collapses randomly into one of the possible states (or eigenstates).

This may sound utterly useless and metaphysical, but it can be observed and has practical implications, particularly when we talk about double-slit experiments and wave/particle duality. I could go in-depth, but the Wiki entry on superposition is pretty decent as far as summarizing it.

I think the biggest problem with QM and woos is that so much of QM is counterintuitive and just-plain-weird that the woos think it justifies anything counterintuitive and weird.

I seem to recall discussion of this "large superposition" issue in the pages of Scientific American. (They used balanced playing-cards for their examples and images, if that helps locate the article.) The upshot was that in practice, a superposition that large (or anything like "human scale") is hopelessly unstable, even without an explicit information transfer. The system collapses into a single result within some unimaginably tiny speck of a finely-ground second.

I am a student at All Saints Catholic school who is currently doing a GCSE course in I.C.T. As part of my course, I have to collect images due to my course relating to a younger audience about eating heathlily. I am asking for your permission if I could use some of the cartoon images to include into my documents.

Thank you for your time
Miss F.O

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