canineraytube
canineraytube t1_j277ik4 wrote
Reply to comment by Aseyhe in How fast does the Milky Way spin? How far does Earth move through space in a year? by Sabre-Tooth-Monkey
To what extent could it be said that the distribution of dark matter changes the effective dimensionality of our galaxy? I ask this because, in contrast to typical circular orbits in our 3+1 dimensional spacetime, which slow with increasing radius, all circular orbits around a given mass in 2+1 dimensional gravity (attenuating at 1/d^1) share the same velocity. Is this coincidental?
canineraytube t1_jddaj5o wrote
Reply to comment by CrustalTrudger in Does the metal in the solid core of a rocky planet have any special properties? by VillagerNo4
>Actually, no.
But the four densest elements—osmium, iridium, platinum, and rhenium—are all in fact highly siderophilic. So wouldn’t we still expect a high concentration of those to be found at the very center of the inner core?