View Full Version : Dual existence


apendrapew
05-23-03, 08:58 PM
My teacher was talking about this today. He said and warned the class before he told about the experiment, "I'm not even going to try and pretend to understand what's going on here"

But he told us about the experiment which goes a little like this. There's a light source that shines light through two slits. When the light goes through the paper, it behaves as a wave and diffracts as it passes through the slits onto the wall.

In another case, if there's a counter, which counts exactly how many photons go through the slits, they exhibit particle-like properties. As a result, the light does not diffract. All of this simply because of an observation. This experiment seems to suggest philosophical implications. This leads me to another question. What if you have a counter counting the photons passing through, but you do not observe the counter. Does it still exibit particle properties?

What if one person observes the counter, while another does not?

Can someone tell me more about this, or at least give me something to read about it?

I know this has something to do with quantum mechanics and how quantum computers will work some day.

Hoth
05-26-03, 01:02 AM
The two split experiment is the basis of the idea of wave-particle duality (note: apparant duality, which only some take as objective duality) and ties in across most all of quantum mechanics.

Illustration: http://einstein.byu.edu/~masong/HTMstuff/quantumEX.html

Some in depth discussions of the various issues:

http://plato.stanford.edu/entries/qm/
http://theory.uwinnipeg.ca/mod_tech/node154.html
http://www.qmw.ac.uk/~zgap118/


Copenhagen types say the two slit experiment shows that observation creates the path. Others disagree with that idealism.

wesmorris
05-26-03, 01:26 AM
Originally posted by Hoth
Copenhagen types say the two slit experiment shows that observation creates the path. Others disagree with that idealism.

I would say that observation allows the path to become meaningful. I don't think there is another path to meaning.

Well, besides a club to the head.

*shrug*

Okay so maybe I don't have a point. It seemed right going in... I'll just stick with it and see what happens.

Siddhartha
05-26-03, 09:25 AM
The photons pass through individually, though to satisfy wave functions in quantum mechanics, they also traverse every one of the infinite possible paths between the light source and the measuring device, often meeting themselves or other photons and cancelling themselves out at points, thus producing the observed wave-like behaviour.