The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos

by Brian Greene

you are anchored to the floor because your body is trying to slide down an indentation in space (really, spacetime) caused by the earth.*

the art of knowing what to ignore.

In an infinite universe, most regions lie beyond our ability to see, even using the most powerful telescopes possible. Although light travels enormously quickly, if an object is sufficiently distant, then the light it emits—even light that may have been emitted shortly after the big bang—will simply not have had sufficient time to reach us.

the task of the theoretical physicist is to figure out which complications in a given context can be discarded, yielding a manageable mathematical formulation that still captures essential details.