19 February 2015

Dark matter could be the wild card in extinction events

by Will Parker

Our planet's long path around and through the Milky Way means that dark matter could be the ultimate wild card in our ability to predict asteroid strikes, and scientists are now speculating that dark matter could also be affecting the Earth's core, potentially leading to major volcanic events.

In a new paper in Monthly Notices of the Royal Astronomical Society, New York University Biology Professor Michael Rampino suggests that Earth's cyclic journey through the galactic disc may have a direct effect on geological and biological phenomena occurring on Earth. He concludes that movement through dark matter may perturb the orbits of comets and lead to additional heating in the Earth's core, both of which could be connected with mass extinction events.

Our solar system resides in the galactic disc of the Milky Way galaxy. It is crowded with stars and clouds of gas and dust, and also concentrations of elusive dark matter - detectable only by its gravitational effects.

The Earth rotates around the Milky Way once every 250 million years, but the Earth's path around the galaxy is wavy, with the Sun and planets weaving through the crowded disc approximately every 30 million years. Analyzing the pattern of the Earth's transitions through the galactic disc, Rampino notes that these disc passages seem to correlate with times of comet impacts and mass extinctions of life - such as the supposed comet strike 66 million years ago that led to the extinction of the dinosaurs.

What causes this correlation between Earth's passes through the Galactic disc and the impacts and extinctions that seem to follow? "While traveling through the disc, the dark matter concentrated there disturbs the pathways of comets typically orbiting far from the Earth in the outer Solar System," Rampino explains. "This means that comets that would normally travel at great distances from the Earth instead take unusual paths, causing some of them to collide with the planet."

Even more remarkably, Rampino suggests that with each dip through the galactic disc, dark matter could accumulate within the Earth's core. "Eventually, the dark matter particles annihilate each other, producing considerable heat. The heat created by the annihilation of dark matter in Earth's core could trigger events such as volcanic eruptions, mountain building, magnetic field reversals, and changes in sea level, which also show peaks every 30 million years."

Rampino's work adds to other theorists who have linked our Solar System's path around the galaxy to Earth-based extinction events. In 2008, Cardiff University scientists said the Earth's galactic cycle "is a beautiful match with the mass extinction events that occur periodically."

Rampino's model of dark matter interactions with the Earth could have a broad impact on our understanding of the geological and biological development of Earth, as well as other planets within the Galaxy. "The history of the Earth is punctuated by large scale extinction events, some of which we struggle to explain," he concludes. "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. As well as being important on the largest scales, dark matter may have a direct influence on life on Earth."

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Source: New York University