## Do I Genghis Khans' electrons?

But, something did hit D and C? Where do they get the electrons to 'shoot'? Have those electrons been transferred to the detector? Whether or not we know which is which, can we say there has been an exchange?

I've only had classical physics so its hard to think of it any other way.

 Quote by Drakkith Furthermore, if you extrapolate this out to atoms and molecules I'm pretty sure we can track where they've been.
Believe me, you don't want to know.

 Quote by chill_factor It is hard to explain this without math so lets take an example. You have 2 electrons running into each other head on when launched from electron beams directed towards each other from beams A and B. They elastically scatter off each other and hit detectors C and D. Can you tell whether A hit C and B hit D, or A hit D and B hit C?
I would take this a step further.

If there is a 50% chance that A hit C and B hit D, and a 50% chance that A hit D and B hit C, then those 2 options BOTH exist in superposition. They both happened.
If these were macroscopic particles like marbles and you performed this experiment you could say that 1 event or the other happened, you just can't tell which one because the marbles are identical. With electrons you cannot say that. All you can say is that 2 electrons were fired and 2 electrons were detected. What happened in between is not just unknowable, it is a sum over all possible histories of the particals.
This is just like the douple slit experiment where a single electron can travel through both slits.
 This question is highly philosophical in nature. Electrons are excitations of the electron field. This field decides at some point in time too look like an electron and sometimes it doesn't. This is also true for all other particles and their respective fields. What we call a human for example is just a giant number of excitations of all these fields. The fact, that a human existed the last second makes it highly likely that a human will exist now. We define that the human existing now to be the same human that existed in the past. For individual electrons this often doesn't make sense. Sometimes we can only say that due to the fact that three electrons existed in one place in the past that three electrons should exist now in some other place, but we cannot make a connection which electron was which. And this is not because we didn't watch them, but because we really have to look at the field and calculate probabilities as to where it might make an electron appear. On a larger level with atoms, giving electrons labels usually makes more sense, and since every breath you take contains atoms of Genghis Khan, it will also contain an electron of Genghis Khan (or to be more precise an electron whose existence became highly likely due to the fact that Genghis Khan existed).