Scientific riddles don’t come much more baffling than this: entire galaxies seem to be in the grip of something that affects their behaviour, but no one knows what this ‘something’ is. If it’s a form of matter, then it must be the most abundant matter in the cosmos, yet all attempts to get a sample of it have failed. Not even the Large Hadron Collider has seen a glimpse of it. It remains as enigmatic as its name: dark matter.
Now, one theorist has provoked controversy with a devastatingly simple explanation for why dark matter still hasn’t been found: it doesn’t exist.
But that’s not the only reason Prof Erik Verlinde of the University of Amsterdam is attracting so much attention. After all, others have previously suggested dark matter may be some kind of illusion.
What sets Verlinde apart is his explanation for the source of the illusion. He believes it’s the result of nothing less than a fundamental misconception about the most familiar force in the Universe: gravity.
It’s a claim that brings Verlinde up against the work of some of the greatest minds in science – including Albert Einstein, whose celebrated theory of gravity is one of the cornerstones of modern physics. Known as General Relativity, it has led to a host of triumphs, including the detection in 2015 of gravitational waves – ripples in the fabric of space-time caused by the collision of two black holes.
The truth about gravity
Verlinde has spent years piecing together clues from theory and observation to create a whole new vision of the force we call gravity. Now his ideas are being put to the test, with intriguing results. And at the centre of them all is the mystery of dark matter.
Verlinde has been hailed as the intellectual successor to Einstein in the media, yet he sees his goal in more down to earth terms. “I’m just trying to explain where gravity comes from,” he says.
That might seem a bizarre statement, coming a century after Einstein showed that gravity is the result of matter warping space and time around it. Yet according to Verlinde, this overlooks the fact that General Relativity remains just a description of the force we call gravity. It leaves unanswered the key question of exactly how matter affects space and time.
To carry out his research, Verlinde has had to grapple with some of the deepest problems in science, including the quest for the so-called Theory of Everything – a theory that unites gravity with quantum mechanics that has been considered the holy grail of physics for decades.
Theorists have long known that General Relativity cannot be the last word about gravity. That’s because it fails to incorporate the other cornerstone of modern physics, quantum theory. As well as describing the subatomic world with astonishing precision, quantum theory has been able to account for all the fundamental forces of nature apart from one: gravity. Since the 1950s, theorists have tried to marry the two views of nature to…
This is an extract from issue 314 of BBC Focus magazine.
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