I've been reading a book over the past week that is titled The God Effect by Brian Clegg. And let me just say right here and now, "WOW!" My mind had been stretched to the limits of comprehension with this one. The author does a fairly decent job in bringing quantum physics to the layman, but I still have to read some of the paragraphs (or pages) 3, 4, or 5 times to wrap my head around ideas such as local reality, Einstein's theories of relativity and special relativity, quantum encryption, etc.
Just to give you an idea of what I'm talking about, I'll chat a little about the concept of local reality (taking an example from the book). Let's say we have a can sitting on a fence post, and we want to knock that can onto the ground. As most of us know the universe and how it works, the can has to be struck. To accomplish this, we can pick up a rock, and by throwing it at the can, transfer our energy into the rock, sending it hurling towards the can, and when the rock strikes the can, it will be knocked down. A directly manipulates B to directly effect C. Local Reality.
Now, here's the good stuff. Two particles that are entangled (as when a photon of light is split into two by some means) can directly effect each other no matter the distance in between. The easiest way I can explain this also comes from the book. If we want to measure the spin state (up or down) of these particles, the mere act of observing collapses the entanglement. However, since the particles are said to be occupying both states of up AND down until observed, when we do finally look at them, the probability of being in a state of up or down is 50 / 50. So, we have 2 particles (A and B) both occupying spin states of up and down simultaneously. We measure the spin of particle A, and discover that at the time of measurement, it's spin is down, and instantly particle B would have a spin state of up, no matter the distance in between. Crazy, right?!
Even though my examples are a little shaky, this is a great book. It goes into detail of time travel, super fast computers, and teleportation technologies (as well as fun things about how your reflection you see in a mirror isn't the original reflection of light) all based off of quantum entanglement. I recommend it because it will learn you some things that you never would even know that you didn't know. Also, the author explains these concepts much better than I.