Along the way, though, some fun candidates have emerged. One of them is string theory, which suggests that the universe is not built out of zero-dimensional point particles but instead is constructed from tiny one-dimensional strings—not tiny like minimarshmallow tiny, but tiny like 10−35 meters tiny. The theory says that these strings can vibrate in lots of ways, and each vibrational mode corresponds to a different particle. When you look at the strings from far enough away (a resolution of only 10−20 meters) they look like point particles because you can’t see their true stringy nature. One
...more
