Answer:
Cosmologists estimate that the acceleration began roughly 5 billion years ago. Before that, it is thought that the expansion was decelerating, due to the attractive influence of matter. The density of dark matter in an expanding universe decreases more quickly than dark energy, and eventually the dark energy dominates.
Explanation:
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Answer:
1988
Explanation:
Dark energy was discovered in 1998 with this method by two international teams that included American astronomers Adam Riess and Saul Perlmutter and Australian astronomer Brian Schmidt.
