Thank you. Dark matter is the issue in cosmology that "it appears as though undetectable matter is present in the universe causing X, Y, Z phenomenon."
The issue that I have with people calling dark matter a theory is that they think it requires matter to solve. It doesn't. MOND is a dark matter theory. It explains(in part) why it appears as though undetectable matter is present in galaxies causing disc velocity to not match expectations.
The issue that I have with people calling dark matter a theory is that they think it requires matter to solve. It doesn't. MOND is a dark matter theory. It explains(in part) why it appears as though undetectable matter is present in galaxies causing disc velocity to not match expectations.