Could dark matter be all around us?
7 Answers
Paddy Alton, PhD in Astrophysics
Answered 220w ago · Upvoted by Stephen Perrenod, physics degree from MIT and astrophysics Ph.D. from Harvard and Erik Nelson, M.S. Physics & Computational Cosmology, University of California, San Diego (2005) · Author has 403 answers and 1.3m answer views
Good question! The answer is yes. Our galaxy, like all galaxies, is thought to live in a large blob of dark matter (a dark matter 'halo'). There are observational reasons to believe this, principally the rotation speed of galaxies. These are very high and that tells us that there's a lot more gravity holding galaxies together than can be accounted for by stars, gas, and dust (i.e. stuff we can detect because it either absorbs or emits light) - which means there needs to be more mass out there that we can't directly detect. There are also good theoretical reasons to believe in this model: es...