Question

What fraction of the mass needed to halt expansion is known to exist in the form of visible mass in the universe?

A) 1 percent
B) 4 percent
C) 22 percent
D) 74 percent
E) 100 percent

Answer 1

Visible mass constitutes about 5% of the universe's critical density, with the remaining 95% being dark matter and dark energy.

Step-by-step explanation:

The fraction of the mass needed to halt expansion that is known to exist in the form of visible mass in the universe is about 5%. This includes the luminous matter in stars and galaxies, as well as neutrinos. Most of the critical density of the universe is not visible as luminous matter; dark matter and dark energy, which have not been detected in earthbound laboratories, are thought to account for roughly 95% of the universe's content. Out of this, dark matter is about 27%, and the mass equivalent of dark energy is approximately 68% according to E = mc².