There's no shortage of theories as to what killed off the dinosaurs millions of years ago – asteroids, volcanoes, climate change, take your pick – but a New York University geologist has suggested a new candidate: dark matter.
Yes, dark matter – the mysterious but invisible stuff that makes up much of the mass in the universe – may have been responsible for the periodic mass extinctions that swept over Earth, according to geologist Michael Rampino.
"It may be that dark matter – the nature of which is still unclear but which makes up around a quarter of the universe –holds the answer," he said. "As well as being important on the largest scales, dark matter may have a direct influence on life on Earth."
His reasoning is as follows: if, as some scientists have theorized, there's a thin disk of dark matter running horizontally through our Milky Way galaxy — then our solar system, on its slow journey around the galactic center, may have occasionally bobbed up and down through it.
That could have had a couple of different effects that led to mass extinctions, he suggested in a study published in the Monthly Notices of the Royal Astronomical Society.
First, he theorized, the sun, as it passed through dark matter, could have generated gravitational waves strong enough to dislodge comets from their usual orbits, sending them on a collision course with Earth, bringing bad news for life on our planet.
A second possibility, he explained, is that dark matter may have accumulated in Earth's core during our journey around the galaxy — eventually self-destructing and releasing sufficient heat to cause worldwide volcanic activity.
Rampino's theories have, predictably, been met with considerable skepticism.
Jo Bovy, an astrophysicist at the Institute for Advance Study in Princeton, New Jersey, says the foundation requirement for Rampino's conjectures – the presence of a layer of dark matter somewhere in the Milky Way – is speculative at best.
"Statistically, there is only a few percent chance that such a thin disk of dark matter exists," he said.
Rampino, for his part, points out that no one has yet been able to identify an unambiguous cause for the dramatic and catastrophic events life on our planet has periodically experienced.
"We are fortunate enough to live on a planet that is ideal for the development of complex life," he said. "But the history of the Earth is punctuated by large-scale extinction events, some of which we struggle to explain."