Sometimes, if you want to understand how nature truly works, you need to break things down to the simplest levels imaginable. The macroscopic world is composed of particles that are-if you divide them until they can be divided no more-fundamental. They experience forces that are determined by the exchange of additional particles (or the curvature of spacetime, for gravity), and react to the presence of objects around them. At least, that's how it seems. The closer two objects are, the greater the forces they exert on one another. If they're too far away, the forces drop off to zero, just like your intuition tells you they should. This is called the principle of locality, and it holds true in almost every instance. But in quantum mechanics, it's violated all the time. Locality may be nothing but a persistent illusion, and seeing through that facade may be just what physics needs.