This means that light travels in straight lines rather than on curved trajectories. If no peaks had shown up, inflation would have difficulties. We'd be back to the drawing board. The ratio of the intensity between the first and second peaks tells scientists how much ordinary matter exists in the universe. The DASI data indicate that ordinary matter, the stuff of which humans, stars and galaxies are made, accounts for only 4.5 percent of the universe's total mass and energy.
Astrophysicists know that eight times as much dark matter exists in the universe.
The 4.5 percent figure agrees with the estimate of ordinary matter that Turner and David Schramm published in 1998 using a completely different method based on the amount of deuterium produced in the big bang. The University of Chicago's Schramm, who died in 1998, was among the first to realize that deuterium was a sensitive indicator of the density of ordinary matter in the universe, Turner said. The underlying physics is completely different. The big bang framework and Einstein's general relativity have passed a major new test. Even though astrophysicists have nearly nailed down the validity of inflation, more work remains.