Wheeler\'s delayed choice (Introduction)

by David Turell , Thursday, August 08, 2013, 23:53 (4125 days ago)

Since one of Ruth's papers is based on Wheeler's famous gedanken experiment I thought I would present a good website description:-"In summary, we have chosen whether to know which slit the particle went through, by choosing to use the telescopes or not, which are the instruments that would give us the information about which slit the particle went through. We have delayed this choice until a time after the particles "have gone through one slit or the other slit or both slits," so to speak. Yet, it seems paradoxically that our later choice of whether to obtain this information determines whether the particle passed through one slit or the other slit or both slits, so to speak. If you want to think of it this way (I don't recommend it), the particle exhibited after-the-fact wave-like behavior at the slits if you chose the screen; and it exhibited after-the-fact particle-like behavior at the slits if you chose the telescopes. Therefore, our delayed choice of how to measure the particle determines how the particle actually behaved at an earlier time."- http://www.bottomlayer.com/bottom/basic_delayed_choice.htm