New ‘Chameleon Theory’ provides insight into dark energy, galaxy formation

The chameleon theory may offer an alternate explanation of origins to Einstein's theory of general relativity
Image: Christian Arnold/Baojiu Li / Durham University

The reconciliation of gravity with our increasing understanding of how the universe works has long been problematic. While Albert Einstein’s General Theory of Relativity–developed around 100 years ago–is an experimentally proven model for the workings of gravity, a new theory may help to fill in some holes left unanswered by General Relativity.

“Chameleon Theory” by no means disproves General Relativity, but rather, offers an alternative way to look at how gravity behaves. The key difference is that General Relativity recognizes gravity as a constant. Chameleon Theory, however, allows for fluctuation in the effects of gravity based on the environment.

Although Chameleon Theory doesn’t debunk General Relativity, it’s still a valid model. Supercomputer simulations have shown that Chameleon Theory would still form a universe with galaxies and black holes, just like the real thing.

Shedding Light on Dark Energy

The study out of the University of Durham, recently published in the journal Nature Astronomy, also offer insights into the mysterious dark energy. While its detection still eludes cosmologists, they believe dark energy accounts for 68% percent of the matter in the universe and could explain why the universe expands rather than contracts under the force of gravity.

Again, General Relativity treats dark energy as a uniform constant, while Chameleon Theory treats the force as a changing variable. Adjusting the variables of gravity and dark matter in the simulation changed how much cosmic gas supermassive black holes consumed, which dictated the number of stars that can form in a galaxy.

“Chameleon Theory allows for the laws of gravity to be modified so we can test the effect of changes in gravity on galaxy formation,” Durham computational cosmologist Christian Arnold says. “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.”

A New Way of Looking at the Universe

Rather than seen as in contention with General Relativity, Chameleon Theory can provide an alternate way of understanding the inner workings of the universe. “Our research definitely does not mean that General Relativity is wrong,” Arnold continued. “But it does show that it does not have to be the only way to explain gravity’s role in the evolution of the universe.”

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After all, both theories produce a universe with familiar galaxies. But by reimaging how gravity works on a cosmological scale, the Durham team hopes that it’s a step in the right direction in discovering what dark matter really is. It’s important, considering that it makes up the majority of the matter in the universe.

The Durham researchers plan to conduct experiments to test their findings through observations at the Square Kilometre Array (SKA). The array resides in both South Africa and Austalia. The team will begin its observations in 2020.