Physicists at Durham University, UK, have now stimulated the cosmos using the f(R)- gravity or the Chameleon Theory. The supercomputer simulations of galaxies have shown that Einstein's theory of General Relativity might not be the only way of explaining how gravity works or how galaxies are formed. The results of the study are published in Nature Astronomy.
The resulting images produced by the simulation show that galaxies like our Milky Way could still form in the universe even with different laws of gravity.
The findings highlight the viability of Chameleon Theory as an alternative to General Relativity in explaining the formation of structures in the universe.
The research could also help further understanding of dark energy.
Albert Einstein had developed General Relativity in the early 1900s to explain gravitational effect of large objects in space and it has become the foundation of modern cosmology.
Scientists have already known from theoretical calculations that the Chameleon Theory can reproduce the success of General Relativity in solar system and now the Durham team has shown that the theory allows realistic galaxies like the Milky Way to form and can be distinguished from General Relativity on very large cosmological scales.
Speaking about it, co-lead author Dr Christian Arnold, said, "Chameleon Theory allows for the laws of gravity to be modified so we can test the effect of changes in gravity on galaxy formation.” He further added, “Through our simulations we have shown for the first time that even if you change gravity, it would not prevent disc galaxies with spiral arms from forming.”
He further added that the research does not mean that General Relativity is wrong, but shows it does not have to be the only way to explain gravity's role in the universe’s evolution.
Researchers looked at the interaction between gravity in Chameleon Theory and supermassive black holes at the centre of galaxies.
Notably, black holes play a key role in galaxy formation because the heat and material they eject when swallowing surrounding matter can burn away the gas needed to form stars, effectively stopping star formation. When the amount of heat spewed out by black holes is altered by changing gravity, affecting how galaxies form.
However, the new simulations showed that even after accounting for the change in gravity caused by applying Chameleon Theory, galaxies were still be able to form.
Speaking about it co-author of the study, Professor Baojiu Li, of Durham University's Institute for Computational Cosmology, said, "In General Relativity, scientists account for the accelerated expansion of the universe by introducing a mysterious form of matter called dark energy -- the simplest form of which may be a cosmological constant, whose density is a constant in space and time.”
He further added, “However, alternatives to a cosmological constant which explain the accelerated expansion by modifying the law of gravity, like f(R) gravity, are also widely considered given how little is known about dark energy."
The Durham researchers expect their findings can be tested through observations using the Square Kilometre Array (SKA) telescope, based in Australia and South Africa, which is due to begin observations in 2020.
