Wed Sep 15, 2004 7:02 pm by Griffon_26
OMG, a thread about quantum mechanics...*sigh* calm down kiddies...I guess your talking about probabilty waves, about particles in a state of being here or there according to probabilty, until we actually observe (take measurements) of it where they become here and not there, and their probability wave collapses elswhere and shoots up to 100 percent to where it is observed? Although there is definantly something there scientists aren't decided as to what this actually means, its called the quantum measurement problem I beleive.
Anyway, has anyone ever looked into the photon (or whatever particle) beam splitter experiments, where photons are fired at say a cardboard wall with 2 slits, one left side on right side, and behind that there is a screen that records where the photons hit. It is found that the photons build up an interference pattern on the screen (some light strips, then a dark strip, then a light strip etc) which shows that they are moving through either slit as a wave, and the peaks and troughs of each wave cancel out each other as they mingle with each other.
However if you slow the firing to the rate of a SINGLE photon of say one every phew seconds, over time it will build up an interference pattern. How can this be? What is causing the interference if only one particle is fired at a time? Well the answer is thought to be probability waves, and it can be said that the particle goes through *both* slits! However, if we want to see which one it went through and set up detectors over each slit to find out wether the particle went through the right slit or the left slit, then we would find that the photons DO NOT BUILD UP THE SAME INTERFERENCE PATTERN as if they would if they were not observed. To counter this, how about we put the detectors far away from the slits, and turn them off until after the particles have gone through the slits, then turn them on. Well we would still find that it does not build up an interference pattern, its as if the past was altered!
Now lets say we do something different, lets say instead of detecting the particle as it goes through a slit, we just label it as say either Left or Right as it passes through the left or right slit. (in real life this is done by altering the particles spin) now because we have observed it, the particle ceases to act like a wave and acts like a particle, so it would not build up an interference pattern. However, say we were to erase the labels, left or right, just before it hits the detector screen. Well since the particles have already passed the split as particles, we cannot expect them to build up an interference pattern, as it needs to act like a wave and go through both slits. However, it DOES build up an interference pattern, even though it could be LONG after it passed the slits! Why does it change like this, just because we observe it?
(remember this is all confirmed by experiments, the only things uncertain is WHY this happens)
Now quantum entanglement, theres another........*no* ok I should shut up now, I could go on all day!
Edited by - Griffon_26 on 9/15/2004 8:02:47 PM
i would tell you what i think but i will only tell it via email cus i dont feel like posting something long and having everyone bug me about it
