Dark Energy as a Modification of the Friedmann Equation

Dark energy could actually be the manifestation of a modification to the Friedmann equation arising from new physics (e.g., extra dimensions). Writing the correction as (1-ΩM)H^α/H₀α-2, we explore the phenomenology and detectability of such. We show that: (i) $α$ must be 1; (ii) such a correction behaves like dark energy with equation-of-state weff = -1 + α 2 in the recent past (10⁴> z 1) and $w=-1$ in the distant future and can mimic $w