Question

based on current evidence, how does the actual average density of matter in the universe compare to the critical density? the actual average density of matter, even with dark matter included, is only about a quarter of the critical density. the actual density of average matter is about twice the critical density. if we include dark matter, the actual average density of matter equals the critical density. the actual average density of matter less than 1% of the critical density.

Answer 1

The actual average density of matter in the universe, including dark matter, is about 0.3 times the critical density. When dark energy is also factored in, the total average density matches the critical density, which allows the universe to continue expanding at its current rate.

Step-by-step explanation:

The question pertains to the comparison of the actual average density of matter in the universe, including both normal and dark matter, versus the theoretical critical density required to halt the expansion of the universe. Critical density is a cosmological concept that denotes the density at which the universe is precisely balanced between expanding forever and eventually recollapsing.

Based on the evidence provided, including current estimates and the standard model of the universe, the actual average density of matter is roughly 0.3 times the critical density, contributed by ordinary matter plus dark matter. In contrast, dark energy contributes around 0.7 times the critical density, leading to a total density that equals the critical density, thanks to its mass-energy equivalence as indicated by Einstein's formula E = mc². Thus, including dark matter and dark energy, the universe achieves a total average density that matches the critical density.