“I soon became convinced… that all the theorizing would be empty brain exercise and therefore a waste of time unless one first ascertained what the population of the universe really consists of.” –Fritz Zwicky
When we look out at the galaxies in the Universe, watching how they rotate, we find that the starlight we see is woefully insufficient to explain why the galaxies move as they do. In fact, even if we add in the gas, dust, and all the known matter, it doesn’t add up.
Normally, we talk about dark matter as the only viable solution, but it turns out that MOND, or MOdified Newtonian Dynamics, is actually superior at explaining galactic rotation to dark matter. Could it be the solution to the “missing mass” (or “missing light”) problem?