Who owns Cross Creek? The red-birds, I think, more than I, for they will have their nests even in the face of delinquent mortgages. . It seems to me that the earth may be borrowed, but not bought. It may be used, but not owned. It gives itself in response to love and tending, offers its sesonal flowering and fruiting. But we are tenants and not possessors, lovers, and not masters. Cross Creek belongs to the wind and the rain, to the sun and the seasons, to the cosmic secrecy of seed, and beyond all, to time. . . "
Tsung-Dao Lee
Since the beginning of physics, symmetry considerations have provided us with an extremely powerful and useful tool in our effort to understand nature. Gradually they have become the backbone of our theoretical formulation of physical laws.
