You've got plenty of scientists as company. There are cute names like WIMP and MOND for different types of hypotheses about what the heck dark matter actually i

You've got plenty of scientists as company. There are cute names like WIMP and MOND for different types of hypotheses about what the heck dark matter actually is, or how to explain what's going on if it doesn't exist at all. Each of these is a huge headache for astrophysicists in one respect or another.