RAS/NYU: Dark Matter, Mass Extinctions & Geologic Upheavals

[bystander]

Does Dark Matter Cause Mass Extinctions and Geologic Upheavals?
Royal Astronomical Society | New York University | 2015 Feb 19

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Research by New York University Biology Professor Michael Rampino concludes that Earth's infrequent but predictable path around and through our Galaxy's disc may have a direct and significant effect on geological and biological phenomena occurring on Earth. In a new paper in Monthly Notices of the Royal Astronomical Society, 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.

The Galactic disc is the region of the Milky Way galaxy where our solar system resides. It is crowded with stars and clouds of gas and dust, and also a concentration of elusive dark matter – small subatomic particles that can be detected only by their gravitational effects.

Previous studies have shown that Earth rotates around the disc-shaped Galaxy 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. Analysing the pattern of the Earth's passes through the Galactic disc, Rampino notes that these disc passages seem to correlate with times of comet impacts and mass extinctions of life. The famous comet strike 66 million ago that led to the extinction of the dinosaurs is just one example.

What causes this correlation between Earth's passes through the Galactic disc, and the impacts and extinctions that seem to follow?

While travelling 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 points out. 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. ...

Disc dark matter in the Galaxy and potential cycles of extraterrestrial
impacts, mass extinctions and geological events - Michael R. Rampino

• Monthly Notices of the RAS 448(2) 1816 (2015 Apr 01) DOI: 10.1093/mnras/stu2708

[Nitpicker]

I haven't read the paper, but it seems to have a very bold conclusion. For one thing, I thought dark matter was most commonly postulated to exist in a more or less spherical shape around the centre of the Milky Way, becoming less dense with increasing radius. Another thing is that there are a lot of scientists who dispute the notion of periodic patterns in the mass extinction events on Earth. Lastly, based on my own simple knowledge of simple harmonic motion, the gravity of the rest of the galaxy en masse (which drives the "wavy " motion of the Sun), would produce greatest accelerations (and hence perturbing forces) on the comets of the Solar System, during the peaks and troughs of the 60 million year, peak-to-peak periodic motion, above and below the galactic plane, not when passing through the galactic plane.