Seasons

So one might say, "Well, let's close slit A. Then we'll know, when we see a scintillum on the screen, that it went through slit A. Then we do the same for B. The total pattern ought to be just the sum of the patterns for A-only and for B-only."
But no! When you close one slit, you get just what you would expect from a classical particle going through such a slit: vrtually all the hits are in a rectangular region of the scren, from which one could see the source. (We make the slits large enough so there is no significant diffraction effect.) The same thing happens when we close slit A and open slit B. The pattern with both slits open is in no way the sum of the patterns obtained with single slits open! [breathes heavily]

So I would guess that what they mean when they say it goes somewhere else is, that an electron goes somewhere else on the screen, when only one slit is open, than it does when both slits are open.

Is this what you are looking at?

http://infophilia.blogspot.com/2006/11/quantum-mechanics-for-dummies-1-wave.html

Oh...the interference pattern also goes away if you put a detector on one slit, even though the detector is of a kind that allows the electron to pass.

The site I cited on my previous post has a (rather small) picture of the two-slit experiment.

I just looked at, and rather like, the Wikipedia article on the two-slit experiment:

http://en.wikipedia.org/wiki/Double-slit_experiment

Here is a more detailed discussion:

http://www.upscale.utoronto.ca/GeneralInterest/Harrison/DoubleSlit/DoubleSlit.html

I still have to insist that they are separate phenomena.

No you don't, because I never said that the wavefunction for light was the same as the classical electromagnetic wave. In fact, I said that they weren't. You are beating an imaginary dead horse. Which is quite a trick...unless you, too, are imaginary...in which case, I, too, must be imaginary...[ponders deeply] ...I'm not sure where that leads me. PETA presumably won't be after you for beating an imaginary dead horse...but what about an imaginary PETA? We could certainly imagine PETA doing that. But horses do not live by PETA bread alone. If you think that horses exist because they think, you are putting DesCartes before the horse. You slipped me some of your absinthe, didn't you? Do you get it from an absinthesizer? Or is that just what tells you how big it is?
I imagine that Psi is imaginary. [sigh]

So, I must be dragged, kicking and screaming, back to that quasi-orgasmic (according to Bev, message 3917) state of working on a problem. Ah, the sacrifices I make!

No no, you have to solve the problem in order to release those endorpnins. Although I gather the longer and harder you work on it, and the more you build up to your solution. You should tak ethe time to start slow, and set up your problem properly. Then you gather momentum, alternating between working slowly and feverishly until the work takes over and you forget everything else until you explode in blinding inspiration, with satisfying spurts of intellectual satisfaction or even multiple solutions. (I am pretty sure those multiply solutions can be expressed as a wave function).

Tell me, have you ever had to fake enthusiasm for your topology text?

I like this one http://www.ncsu.edu/felder-public/kenny/papers/quantum.html
<-2>We'll start with the single-slit experiment. Instead of a light source, we have an M&M-throwing-machine. Each M&M is covered with white ink so that it leaves a stain on the black wall behind (since, as we all know, the milk chocolate only melts in your mouth). You set your M&M-throwing-machine going, it throws out a ton of M&Ms one at a time, and then you look at the ink pattern on the wall—this will tell you where the M&Ms hit. What do you see? Well, the machine is just mechanically spitting out M&Ms in the same way every time, so of course there is just one spot on the wall, where they all hit. M&Ms, unlike light, don't radiate outward in all directions: they just follow a single course to a single destination.

So that wasn't much fun. Let's mix it up a bit: say, stand behind the M&M machine and rattle it around a lot, so the M&Ms get thrown off in all directions. Now, a lot of them bounce off the cardboard. The ones that get through tend to hit the wall near the slit, but not all right behind the slit. So, after enough M&Ms hit, you get a result very much like the single-slit experiment with light: a big white bar that gets dimmer as you move out.

Now, let's add a second slit and do it again, still throwing M&Ms at random angles. What do you see this time? Are there alternating bands of white and black? No, certainly not. Since we are throwing the M&Ms one at a time, what you will see is all the ink from M&Ms that went through the left slit, and all the ink from M&Ms that went through the right slit, added together. So there aren't any bands that suddenly go dark. There's a big white bar behind each slit, and it gets darker as you go away from the slits.



(Note from our lawyers: the authors of this paper accept no responsibility for the consequences if you attempt to repeat this experiment at home.)

PS yeah, I need help. At least I'm not hitting on a toaster.

Prob123, did you use really fine print or did my expression of intellectual self gratification make me go a little blind?

Oooh! Now, This site has really cool graphics! (Did I use "cool" correctly?)

http://www.colorado.edu/physics/2000/schroedinger/index.html