If you don't mind, break this down more for me.
ok this might be multiple posts -- mainly because this has got me thinking more deeply about quantum entanglement. feynman once said, if you can't explain it simply, you don't understand it. i will start by admitting i don't fully understand quantum mechanics. it exists at the boundary of my intuition of the physical world.
first, let's start with the an observation on the universe: things like photons, electrons, etc. have "particle-like" (e.g. think of a cannon ball) and "wave-like" (e.g. think of a ripple in a pond). we can concretely say which direction an electron is traveling (like a cannon ball being fired), but we can't firmly say where it is at a given period of time.
this is where things get wonky, and you might have to take a leap of faith. let's imagine for a moment that you have an infinite supply of free electrons at rest. now, we accelerate these electrons one at a time through a magnetic lens (e.g. like the electron guns in old boob tube tv's) at a wall at a distance. what would the impact crater on the wall look like? Well mainly, like a normal impact crater you expect from a bullet, cannon ball, your favorite projectile.
now, we repeat the experiment, but add a second wall, perfectly parallel, but in between the first wall and the electrons. this second wall, however, has a small pinhole that is perfectly in the line of fire of the electron. what does the impact crater look like? well it's similar to the first impact crater, except you will see two smaller, impact craters to the side of the main one. in fact, if you have a careful microscope, you'll see an infinite number of significantly smaller impact craters all parallel to that main crater. why does this happen? because the electron has a wave-like property of it's position. this is known as the single-slit interference phenomenon. each electron only lands in a single crater, but the *ensemble* of infinite electrons exhibit this interference pattern. we assume, based on this observation, that the position of the electron is probabilistic.
okay, a bunch of math later, electrons in confinement (e.g. bound to an atom nucleus) observe the same type of probabilistic position. but they are catty little bitches, and hate each other. they hate each other so much, that they need to be *maximally separated* from one another. this is mathematically described by their quantum numbers, and is phenomenally described as the "Pauli exclusion". Any two electrons can share all their quantum numbers except for one -- let's call the one they don't share "spin". spin is a fundamental property of the particle, but we know we can measure spin with magnetic fields. once the pair electrons have been confined into a single space, they always choose opposite spin positions.
Basically, electrons are like my wife and my sister-in-law. If my wife says she likes "blue", her sister will say she likes "red". If my wife changes her mind and says she likes "red", the sister will immediately change her mind and say she likes "blue". those pair of electrons, operate the same way. if you change the spin of one, you *automatically* change the spin of the other. this is called quantum entanglement.
more to come later on this....
