We point out that, due to the nonlinearity of the Einstein equations, a, homogeneous approximation in cosmology leads to the appearance of an additional term in the Friedmann equation. This new term is associated with the spatial inhomogeneities of the metric and can be expressed in terms of density fluctuations. Although it is not constant, it decays much slower (as t -2/3) than the other terms (like density) which decrease as t -2. The presence of the new term leads to a correction in the scale factor that is proportional to t2 and may give account of the recently observed accelerating expansion of the universe without introducing a cosmological constant.
- Relativistic cosmology
ASJC Scopus subject areas
- Nuclear and High Energy Physics
- Astronomy and Astrophysics
- Physics and Astronomy(all)