Approximately about 20 years ago, the scientists drew a conclusion that the universe is expanding and also that this expansion is speeding up.
They explained it by introducing a force called “dark energy” that pushes the space apart. When the cosmologists began studying cosmic acceleration, they kicked off the concept of “cosmological constant” provided by Einstein. This cosmological constant is interchangeable with dark energy. The mathematicians such as Temple, Vogler, Davis, Smoller were not satisfied with that explanation. They began their research to figure out the cause of anomalous acceleration of the galaxies within Einstein's original theory without dark energy. It is known that the “Friedman universe” assumes that all matter is expanding. At the same time, it is evenly distributed in space at every time. The mathematicians estimated that the equations of General Relativity show the instability of the Friedmann space- time. This reflects that the local time spaces that accelerate faster should be measured rather than unstable Friedmann universe. The mathematicians concluded that the best method to establish the acceleration of the galaxies is through the Einstein’s original theory of General Relativity. There is no need to make reference to the cosmological constant/dark energy at all.
By: Anuja Arora