Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Observed peak flux from supernovae of type Ia, as a function of red shift (= distance); Lower reiterates Upper, with the overall gradient removed. Shown are the predictions of different cosmological models (see text). The data favor the Upper model, in which the universe’s expansion is accelerating, due to a cosmological constant (11, 12).
