Calculations of the relativistic effects in many-electron atoms and space-time variation of fundamental constants

Theories unifying gravity and other interactions suggest the possibility of spatial and temporal variation of physical "constants" in the Universe. De tection of high-redshift absorption systems intersecting the sight lines to wards distant quasars provides a powerful tool for measuring these variatio ns. We have previously demonstrated that high sensitivity to the variation of the fine-structure constant alpha can be obtained by comparing spectra o f heavy and light atoms (or molecules). Here we describe new calculations f or a range of atoms and ions, most of which are commonly detected in quasar spectra: Fe II, Mg II, Mg I, C II, C Iv, N v, O I, Al III, Si II, Si rv, C a I, Ca II, Cr II, Mn II, Zn II, Ge II (see the results in Table Ill). The combination of Fe II and Mg II, for which accurate laboratory frequencies e xist, has already been used to constrain alpha variations. To use other ato ms and ions, accurate laboratory values of frequencies of the strong E1 tra nsitions from the ground states are required. We wish to draw the attention of atomic experimentalists to this important problem. We also discuss a me chanism which can lead to a greatly enhanced sensitivity for placing constr aints on variation on fundamental constants. Calculations have been perform ed for Hg II, Yb II, Ca I, and Sr II where there are optical transitions wi th the very small natural widths, and for hyperfine transition in Cs I and Hg II. [S1050-2947(99)04601-6].