How many metrics are there in special relativity and in general relativity? Can one metric be transformed into another? Can objects that don't have spherical symmetry have metrics? Is it possible for two different manifolds to intersect and for their metrics to be equal where they intersect? Do supermassive black holes have Schwarzschild metrics? If all the mass in the universe is at one point, space-time doesn't exist and nor does the concept of a metric.Do metrics become invalid at more normal mass-densities? Are metrics conserved:if a black hole evaporates, does a new black hole appear elsewhere in the universe? What sort of metric describes the space-time around a single proton? If a graviton has energy that curves space-time, what would its metric be?