User:Jordgette/DarkEnergyAlternatives

Alternative ideas

Some alternatives to dark energy aim to explain the observational data by a more refined use of established theories, focusing, for example, on the gravitational effects of density inhomogeneities, or on consequences of electroweak symmetry breaking in the early universe. Light from distant supernovae passes through voids containing very little matter, and due to relativistic effects, time in such regions would appear to run faster than it does from our vantage point inside a massive galaxy. The expansion of space being a function of time, space would appear to be expanding more rapidly in these voids. While weak, such effects considered cumulatively over billions of years could become significant, creating the illusion of cosmic acceleration, and making it appear as if we live in a Hubble bubble.^[1][2][3][4]

Another class of theories attempts to come up with an all-encompassing theory of both dark matter and dark energy as a single phenomenon that modifies the laws of gravity at various scales. An example of this type of theory is the theory of dark fluid. Another class of theories that unifies dark matter and dark energy are suggested to be covariant theories of modified gravities. These theories alter the dynamics of the space-time such that the modified dynamic stems what have been assigned to the presence of dark energy and dark matter.^[5]

Another set of proposals is based on the possibility of a double metric tensor for space-time.^[6][7] It has been argued that time reversed solutions in general relativity require such double metric for consistency, and that both dark matter and dark energy can be understood in terms of time reversed solutions of general relativity.^[8]

Christos Tsagas, a cosmologist at Aristotle University of Thessaloniki in Greece, has argued that the accelerated expansion of the universe is an illusion caused by the relative motion of us to the rest of the universe. The peer reviewed journal entry cites data showing that the 2.5 billion ly wide region of space we are inside of is moving very quickly relative to everything around it. If his theory is confirmed, then dark energy would not exist (but the "dark flow" still might).^[9][10]

References