Question

how has scientific understanding about the composition of the universe changed over time? select the two correct answers. (1 point)the percentage of dark matter has shrunk in scientists estimates since the 1980s.the percentage of dark energy has shrunk in scientists estimates.the percentage of unknown material has grown in scientists estimates since the 1970s.the percentage of ordinary matter has grown in scientists estimates.

Explanation:

1. Over time, astronomers revised estimates: dark matter's estimated percentage decreased since the 1980s as dark energy was discovered and quantified.
2. Since the 1970s, scientists have learned most of the universe is made of unknown dark matter and dark energy, so the estimated percentage of unknown material has grown.
3. Estimates of dark energy have increased, not shrunk, and estimates of ordinary matter have decreased, not grown.

Answer:

• The percentage of dark matter has shrunk in scientists' estimates since the 1980s.
• The percentage of unknown material has grown in scientists' estimates since the 1970s.