Quantum Indeterminacy

[Barquentine]

What happens to the photon in the double-slit experiment if no one ever looks at it? Until someone looks it was in a wave-form set of alternate states (I think?), so if no one bothers to look does it just stay hovering in a multitude of possible outcomes?

[R1Geezer]

all I'll say about quantum theory is that if you don't find it disturbing you haven't understood it!

[Barquentine]

Thanks for your input R1Geezer. I didn't say I didn't find it disturbing; then again, maybe I did. Maybe I'm in a quantum hyperstate of indeterminacy myself. Maybe until someone looks I won't have made up my mind one way or another. Maybe I'll be in two minds simultaneously. I do wish someone would look in my box to see what state I'm in!!

[Clanad]

I'm sure you're aware that this is exactly the premise discussed in Schr�dinger's Cat theory of superposition, no? It's as much to do with philosophy (or perhaps Metaphysics) because in the end, there's no answer and it doesn't really matter anyway...

[jake-the-peg]

What your asking is effectively what is called the an "interpretation" of quantum mechanics.

There are several see here:

http://en.wikipedia.org/wiki/Interpretation_of _quantum_mechanics

Quantum mechanics does not explain how and why things happen what it does is gives a ery powerful very accurate way of calculating the probability of certain events.

If you try to figure out what is happening using your everyday experience you will fail because you don't have everyday experience of quantum events. It's like an undiscoverred Amazonian tribe tring to figure out how a plane flies based on a canoe.

A lot of people really hate this - Einstein was one and Shroedinger was another - that's why he devised the cat thought experiment - top show how ludicrous it was.

The Irony is that that very thought experiment is now one of the classic illustrations of quantum theory....

[jake-the-peg]

...ctd.

Anyway it's actually unknowable what "happens" but that hasn't stopped people coming up with these interpretations. The many worlds is probably the most famous - SciFi writers love it to death.

But in reality it is not possible to devise an experiment to differentiate between them so in a very real sense it's a question that science cannot answer.

Try asking a budhist - I believe they're big on trees falling in empty forests :c)

[mibn2cweus]

If you wait long enough to look . . . it's almost certain the cat is dead . . . ~O">

[R1Geezer]

I was just saying what others above have said more thoroughly. Understanding quantum mechanics requires that you throw away all previous ideas of reasoning!

[beso]

There is actually a way of imaging an object using the double slit design without actually photons falling on the object .

A special filter is used to increase the probability of the photons travel along one of the double slit paths. The proportions can be arbitrarily designed by the filter.

With a limited number of photos it is possible for every photon in the experiement to take just one of the two paths. However the presence of an object blocking the potential alternative path can be detected by absence the interference pattern. If an object blocks the path there will be no diffreaction pattern but of the path is open the diffraction pattern will appear yet no photon was blocked by the object.

I can't find any site explaining this so if you can please link.

The original explanation I saw was in Scientific American many years ago.

For the mythologist: They even postulated that Herecles may have been able to combat the Hydra using this mechanism. The mythology holds that anyone who looked at the Hydra would immediately die so it was impossible to fight it.

The article questioned if "looking" involved the reflection of light falling onto an object and this unusual diffraction mechanism may not technically be "looking". Therefore Herecles could locate the Hydra without looking and slay it.

[Barquentine]

Jake I also heard about some experiment called 'Watching the Quantum Pot' which seemed to say that the more frequently that observations were made, the less likely the (caesium) electrons would jump up to their next energy level when being 'heated' by some kind of radioactive input (I forget exactly how it worked - not that I understood much in the first place). I think the article was suggesting that things change only because they are not observed all the time. I'm not sure how this fits in with the doble-slit experiment. Maybe that isn't comparing like with like? It doesn't matter how many times I re-read this stuff; I just can't seem to grasp what they are saying! I need a biger brain!