Rupendra Brahambhatt writes:

According to the theory of general relativity, a galaxy must have a certain amount of mass to be held together by gravity. However, scientists don’t see enough visible mass in many galaxies in the universe, yet gravity keeps such galaxies intact. How’s this even possible?

This is where the concept of dark matter comes into play. Scientists believe that galaxies have invisible mass in the form of matter that doesn’t interact with light. The gravity holding these galaxies exists because of this invisible mass.

For decades, this explanation has supported the existence of the hypothetical dark matter. However, a new study claims that gravity can exist even without mass, potentially eliminating the need for dark matter altogether.

This unique theory “is in turn driven by my frustration with the status quo, namely the notion of dark matter’s existence despite the lack of any direct evidence for a whole century,” Richard Lieu, study author and a distinguished professor of physics and astronomy at the University of Alabama in Huntsville (UAH), said.

According to Lieu, the gravity needed to hold some galaxies or clusters together might come from “shell-like topological defects.”

Topological defects are unique compact structures in space that have a high density of matter.

Such defects likely first occurred in the early universe during phase transition — an event during which matter throughout the universe goes through a major physical change. [Continue reading…]