how do we know electrons have different behaviours depending if they’re being observed or not? What are those behaviours?

Question

how do we know electrons have different behaviours depending if they’re being observed or not? What are those behaviours?

In: 7

Answer 1

Here’s an experiment –

Make an electron machine gun and fire it at a piece of paper, what do you see? You basically see a bunch of “bullet holes” on the paper clustered around the target just like you would with a real machine gun.

Now put an electron proof shield between the gun and the target and cut a tiny, tiny little hole into it, what do you see? You see a tinier little cluster of bullet holes on the target, only in the place where an electron could have traveled through the hole.

Now cut a second, tiny tiny hole in the shield AND aim the machine gun directly between the two holes. In theory the only way a bullet can leave the gun, go on an angle and through the hole, and then on to the target would be for really errant shots off to the side. What do you see?

Suddenly you see a weird alternating series of bullet holes – no bullet holes – bullet holes – no bullet holes splayed left to right across the target. *None* of the bullet holes corresponds to a place where a bullet could physically have gone from gun, to hole, to target. WTF is happening?

Perhaps, you think, two bullets are somehow traveling through the holes at almost the same time, and somehow they are *hitting* each other an ricocheting into that pattern.

So you have an idea, you put a metal detector over the holes, if a bullet travels through the hole the detector goes off and you which hole has a bullet and when. The important thing is a metal detector has no effect on bullets, it doesn’t bend them or something, right?

You rig this up and turn it on, what happens? The moment you flip the switch the pattern on the target instantly reverts to the two small splotches of straight line fired bullets and the pattern disappears. What? You flip the switch back off and the alternating pattern instantly reappears, flip it on, back to two splotches.

This is called the double slip experiment, you can google it for more info.