The author explains it pretty well in the Batchelor interview: https://audioboom.com/posts/4827661-mass-extinction-and-the-structure-of-the-milky-way-joint-hor

The author explains it pretty well in the Batchelor interview: https://audioboom.com/posts/4827661-mass-extinction-and-the-structure-of-the-milky-way-joint-horner?t=0 https://audioboom.com/posts/4827661-mass-extinction-and-the-...