The universe is believed to be constantly expanding since the Big Bang. This expansion rate was said to be relatively consistent for the first eight years due to gravitational force. However, some missions revealed that the expansion has been accelerating in the last five billion years. Many attributed this acceleration to either a mysterious force called Dark Energy or a change in gravity. But, a new study suggests that the nature of gravity has remained constant for the entire history of the universe. As per Einstein’s General Theory of Relativity, the curvature of space-time gets altered due to gravity. This theory has proven accurate in predicting a host of phenomena in the universe including the existence of black holes and gravitational lensing.
Despite this, scientists grew skeptical of the theory when they noticed some discrepancies. One of those was that the gravitational effects of massive cosmic structures were not in line with their observed mass. This skepticism spawned the theory that space is filled with invisible mass. The expansion of the cosmos, meanwhile, gave rise to the theory of Dark Energy and the Lambda Cold Dark Matter (Lambda CDM) cosmological model.
To make things clearer, researchers from the Dark Energy Survey (DES) Collaboration have used the Cerro Telolo Inter-American Observatory’s Victor M. Blanco 4-metre telescope in Chile and observed galaxies up to 5 billion light-years away. With this, they aimed at determining if gravity has changed in the past 5 billion years.
The team observed the images and noticed the subtle distortions in them due to dark matter. This distortion of space-time by a gravitational lens helps scientists to know the strength of gravity. The DES team too utilised this method and measured the shapes of more than 100 million galaxies with all their observations matching the predictions of the General Relativity theory.
The findings were published in a paper in the American Physical Society journal Physical Review D.