Final answer:
The visible parts of galaxies contribute approximately 5% of the critical density of the universe, not one-tenth, with 1% from luminous matter and an additional 4% from interstellar hydrogen and helium.
Step-by-step explanation:
The statement that the visible parts of galaxies contribute about one-tenth of the critical density of the universe is false. According to current best estimates, luminous matter in stars and galaxies, including neutrinos, contributes roughly 1% of the mass needed to reach critical density. An additional 4% comes from hydrogen and helium in interstellar and intergalactic space. Most of the critical density, about 95%, is attributed to dark matter (approximately 27%) and dark energy (about 68%). This means that the combined contribution of dark matter and dark energy vastly outweighs the contribution of visible matter in galaxies.