Harvard University Department of Astronomy

The Cosmological Constant Theories of Lambda and maybe not lambda Basic Idea: theorists are very puzzled. Measurable by gravity which is not well understood force. Puzzles Don't know how to calculate it Size seems unnatural relative to gravitational scales Seems many contributing effects Size relative to other energy densities changes with time, why comparable to other scales today? Methods to try to explain it (courtesy J. Lykken) give up anthropic some unrecognized symmetry existing hierarchy dynamics original counting wrong strings: some models of the universe ways to get lambda small with arguments of type above Analogy with inflation quintessence--same thing happening now? scalar field description link to inflation using same field Some references. Home Syllabus References Lecture References Useful Links Contact Info