The cosmological constant (Ʌ ) is equated to dark energy and has units of energy/volume. Why have I read that Ʌ equals the Hubble constant squared (H2) which has units of 1/sec2? There must be an obvious explanation.
...Why have I read that Ʌ equals the Hubble constant squared (H2) which has units of 1/sec2? ...
Marcus, thanks for the explanation relating a curvature constant to energy density.
A number I have referenced for the value of dark energy is 5.81 x 10-30 gm/cm3 (assuming it exists) which is very close to what you quoted (5.2 joule/km3 to your .54 joule/km3).
Is there an online reference that shows the Friedmann and Einstein equations with units (setting c = 1 is always confuseing)?
Is the calculator you referenced the Ned Wright calculator?
Oh no! You sound discouraged. I've failed to understand what you were curious about, and proceeded in the wrong way.Thus, my question on scale is beyond my math ability.
As far as we know "dark energy" is fictional--an artificial convention. I think it became a fashionable idea after 1998 when it was found that instead of being zero (as most people had assumed) the Ʌ constant in GR equation was a small positive curvature.