Cosmology has reached an era where precise calculations can be made of the contri butions of ordinary matter and radiation, dark matter, and dark energy, to the energy density of the universe. our universe at this time is thought to be dominated by dark matter and dark energy, which together make up about 95% of the energy density. or- di in the following, ? ? is the current nary matter and radiation make up the last 5% value of the density of dark energy, and s2m refers to the energy density of everything .all al mar, dark matter, aul ralati. a) what is the effect of dark energy on the expansion of the universe? explain how type ia supernova observations are used to constrain the relative contributions of dark energy and all other matter to the energy density of the universe.