However, our uncertainty about the present average density of the universe is even greater.
然而,我们对目前宇宙平均密度的不确定性更大。
传说之境
While Oahu has an average density of about 1700 people per square mile, a massive 34 times as dense as the Big Island and denser than any US state is on average.
This is what makes the Big Island an overall very rural place in comparison with an average population density of only about 50 people per square mile which is about the same as the state of Maine.
The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume. The symbol most often used for density is ρ (the lower case Greek letter rho), although the Latin letter D can also be used. Mathematically, density is defined as mass divided by volume: