Features numbers that define the essence of the Universe. They tell us how strong its forces are, and what its fundamental laws can do: the strength of gravity, of magnetism, the speed of light and the masses of the smallest particles of matter. They express our greatest knowledge and our greatest ignorance about the cosmos.

Constants of Nature are the numbers that define the essence of the Universe. They tell us how strong its forces are, and what its fundamental laws can do: the strength of gravity, of magnetism, the speed of light and the masses of the smallest particles of matter. They express our greatest knowledge and our greatest ignorance about the cosmos. Yet, while we have become skilled at measuring the values of these constants, our frustrating inability to explain or predict their values shows how much we still have to learn about the inner workings of the Universe.