Looking Forward to interpreting the movements of galaxies

Prof. Mordehai Milgrom: "Of course, I enjoy the recognition brought about by my discoveries; but what is much more gratifying to me is the process I went through in trying to understand how the universe works and why galaxies exist as we know them – the knowledge that I've had a part in the revealing of truth."

Why Do They Exist?

The universe behaves as though it contains much more matter than what's on display. Though galaxies may hold billions of stars, to stay together they would theoretically need ten times more matter than we see through our telescopes. According to calculations based on Newton's laws and Einstein's theory of relativity, galaxies should be breaking up, their celestial objects moving off in all directions. But galaxies do, in fact, exist, and this has led many scientists to postulate the existence of "dark matter," which has not yet been seen or detected, to explain why galaxies keep themselves whole.

Astrophysicist Prof. Mordehai (Moti) Milgrom of the Condensed Matter Physics Department has suggested a new approach to the issue – one that doesn't invoke dark matter. His approach goes, rather, to the basis of the calculations themselves – Newton's laws of motion and the theory of relativity, which, he postulates, require major amendment. It's known that Newton's laws are violated in extreme circumstances: When a moving object approaches the speed of light, for instance, relativity takes over from Newtonian laws. And at the extraordinarily tiny scale of subatomic particles, the rules of quantum mechanics replace Newtonian and relativistic laws of motion. In Milgrom's theory, the conventional laws of motion are essentially valid for the solar system, but on the colossal scale of galaxies, they need serious readjustment. A growing minority of scientists has been coming over to this theory, which has been steadily garnering interest, as well as support from various astrophysical studies.

Prof. Mordehai Milgrom is the incumbent of the Isidor I. Rabi Chair of Physics.