Mass of the Universe

This equation provides an estimate of the mass of the observable universe.

According to an article posted on the University of Massachusetts website  ¹ , "the mass density of visible matter (i.e., galaxies) in the Universe is estimated at `3 X 10^-28 "kg"/m^3`, while "the radius of the visible Universe is estimated at `1.7 X 10^26 m` (18 thousand million lightyears) plus or minus 20 percent or so". This translates to a mass of `6 X 10^51 kg` , which is equivalent to the weight of `4 X 10^78` hydrogen atoms.

1. ^ Mass, Size and Density of the Universe