The Bullet Cluster has, for almost 20 years, been hailed as an empirical “proof” of darkish matter. Can their detractors clarify it away?
It’s some of the well-accepted concepts within the Universe, and but some of the controversial: the notion of darkish matter. Right here within the Photo voltaic System, the Solar and planets are sufficient to elucidate all the gravitational results that we see: merely use the legislation of Basic Relativity and what you expect matches what you observe precisely. However on bigger scales — the scales of galaxies, teams and clusters of galaxies, and even the grand cosmic internet — the traditional matter that we all know of, together with all the pieces made from protons, neutrons, and electrons, merely isn’t adequate to elucidate what we observe. Another large ingredient, i.e., darkish matter, is required to convey issues again into alignment.
On the size of a single galaxy and under, different explanations, equivalent to modifications to gravity, are simply as profitable as darkish matter, with MOND being a main instance. In actual fact, exams of huge binary stars might quickly be capable of check these concepts in opposition to the notion of darkish matter immediately. However on bigger cosmic scales, such because the scales on which clusters of galaxies collide, those self same modifications of gravity are not any…
