It seems that perhaps the easiest way to begin describing what quantum mechanics is is by describing what quantum mechanics is not.
Or, put another way, by describing what’s known as classical mechanics.
Classical mechanics is what you learned in seventh grade science class.
Apples fall from trees, hit you in the head (jerks!), then land on the ground. They stay there until you pick them up or some violent storm carries them off in the wind. To overgeneralize a bit, this is the realm of Isaac Newton.
That’s not to say that classical mechanics is simple. Rather, it’s generally used to describe and predict those aspects of the world which we can observe with our eyes.
Space ships are pretty easy to see. Controlling them is an entirely different matter.
Quantum mechanics, on the other hand, describes the invisible world.
That, once again (and like pretty much every other statement in this post), is an over-generalization. But it’s as good a place as any to begin our discussion.
We first started studying the world of the ‘quantum realm’ in the early 20th century, around the time of Einstein. His work played a crucial role in opening the door to the field, though (quite ironically) he hated what was found there more than almost anyone else.
One way to think about the difference is that quantum mechanics describes motion on an unfathomably small scale, while classical mechanics describes motion on just about every other scale we commonly think about.
Quantum mechanics describes the motion of particles.
How big is a particle? I have no idea. I hear it’s pretty darn small. See what I mean?
But the thing is… you and I are ultimately composed of particles. So are apples and space ships and (I’m pretty sure) everything else in the universe.
So what applies to particles has to at least in some sense apply to the rest of us, right?
Well, as we’ll explore throughout the rest of the week, that would be a bizarre and even frightening prospect.
*Photo Credit: Tim Daniels (Creative Commons)