Chameleon Theory Challenges Einstein's Ideas About Gravity

Jul 29, 2019

Einstein's theory of general relativity was revolutionary when it was introduced. Over the past century, aspects of the theory have been proven in experiment after experiment and much of it has become an assumed underpinning of daily life, even for non-scientists.

Take Einstein’s description of gravity.

Gravity is gravity, right? How strong it is depends on the mass of the objects involved. Or maybe not.

Scientists have been struggling to account for the majority of mass and energy in the universe. Decades of searching have so far failed to turn up a new particle to fill the void of so-called dark matter.

A new idea called chameleon theory takes a different approach.

“In chameleon theory, the strength of gravity changes both over time and within space,” Christian Arnold told Living Lab Radio. Arnold is physicist at Durham University in England who has been developing the theory.

In a less-dense region of the universe, say, a cosmic void, the forces described in chameleon theory are stronger compared to those described by general relativity. Meanwhile, in our solar system, the forces in chameleon theory work the same way as they do in general relativity.

“So, in this way, the theory changes its behavior or its color like a chameleon,” Arnold said.

Arnold and his colleagues ran supercomputer simulations of the evolution of the universe to test if realistic galaxies could form using chameleon theory. It worked.

“What we found was that galaxies like our Milky Way—so spiral galaxies, the spiral arms and a disk like shape in the stellar structure—can actually form,” he said.

Does that mean Einstein was wrong?

“It's very possible that we find out in a couple of years our theory is actually wrong and Einstein's works much better,” Arnold said.

“But I think, as a physicist, you have to constantly keep challenging theories and ideas and think in new ways. Otherwise you won't make any progress.”


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