Today, Scientific American reports:
This Weird Galaxy Is 99.99 Percent Dark Matter
Usually, we use kg or g to describe matter, be it ordinary or dark, and we also use joules or ergs to describe energy.
Well, as I checked out Dark Matter and Dark Energy in Wiki, I found it says:
Again, on a mass–energy equivalence basis, the density of dark energy (~ 7 × 10−30 g/cm3) is very low, much less than the density of ordinary matter or dark matter within galaxies.
What? It has used g/cm3 to directly describe dark energy. Although Einstein's equation E=mc2 offers energy-mass converting relationship, the use of g as the unit of energy is new to me.
My question is: is g used properly here? Does it stand for gram?
Thanks in anticipation