The nature of dark energy is still not fully understood, and scientists are actively researching its properties. Dark energy is believed to be responsible for the observed accelerated expansion of the universe, but its exact composition remains unknown.
Currently, the most widely accepted model of dark energy is the cosmological constant, represented by the symbol Λ (lambda). The cosmological constant is a measure of the energy density of empty space. However, the cosmological constant is not considered to be a true "density" in the same sense as matter or energy.
In the context of the cosmological constant, the energy density of dark energy is thought to be around 7 x 10^-30 grams per cubic centimeter. This value is extremely low compared to the density of ordinary matter or even dark matter in the universe. It implies that dark energy is very diffuse and spread out throughout the vastness of space.
To provide a rough estimate of the amount of dark energy per cubic kilometer (km^3), we can convert the density from grams per cubic centimeter to grams per cubic kilometer. There are 1 x 10^15 cubic centimeters in a cubic kilometer. Therefore, multiplying the dark energy density by this conversion factor gives us approximately 7 x 10^-15 grams of dark energy per cubic kilometer.
It's important to note that this estimate assumes dark energy behaves like the cosmological constant. If other models or theories of dark energy are considered, the density and distribution may differ. As our understanding of dark energy evolves, our estimates and knowledge about its properties may also change.