The analyses showed that there are two-dimensional objects called, naturally enough, membranes (another possible meaning for the “M” in M-theory) or—in deference to systematically naming their higher-dimensional cousins—two-branes. There are objects with three spatial dimensions called three-branes. And, although increasingly difficult to visualize, the analyses showed that there are also objects with p spatial dimensions, where p can be any whole number less than 10, known—with no derogation intended—as p-branes. Thus, strings are but one ingredient in string theory, not the ingredient.
