The researcher suggests that gravity can exist without matter, which alleviates the need for a hypothetical dark matter

Dark matter is a hypothetical form of matter that is implied by gravitational effects that cannot be explained by general relativity unless there is more matter present in the universe than can be seen. It remains virtually as enigmatic as it was nearly a century ago, when Dutch astronomer Jan Oort first proposed in 1932 to explain the so-called “missing matter” necessary for things like galaxies to cluster together.

Now Dr. Richard Lieu at the University of Alabama in Huntsville (UAH) published an article in Monthly Notices of the Royal Astronomical Society which shows for the first time how gravity can exist without matter and provides an alternative theory that could potentially alleviate the need for dark matter.

“My own inspiration came from my quest to further solve the gravitational field equations of general relativity—a simplified version of which, applicable to the conditions of galaxies and galaxy clusters, is known as Poisson’s equation—which gives the ultimate gravitational force. in the absence of any detectable matter,” says Lieu, Distinguished Professor of Physics and Astronomy at UAH, part of the University of Alabama system.

“This initiative, in turn, is driven by my frustration with the current state of affairs, namely the notion of the existence of dark matter despite the lack of any direct evidence for a century.”

The researcher claims that the “excess” gravity necessary to hold a galaxy or cluster together could be caused by concentric sets of shell-like topological defects in structures commonly found throughout the universe, which were most likely created during the early universe when a phase transition occurred. . A cosmological phase transition is a physical process where the overall state of matter changes together throughout the universe.

“It is currently unclear what exact form of phase transition in space could lead to topological defects of this kind,” says Lieu.

“Topological effects are very compact regions of space with very high matter density, usually in the form of linear structures known as cosmic strings, although 2D structures such as spherical shells are also possible.

“The shells in my paper consist of a thin inner layer of positive matter and a thin outer layer of negative matter; the total mass of the two layers – which is all that can be measured in terms of mass – is exactly zero, but when the star lies on this shell it experiences a large the gravitational force pulling it toward the center of the shell.”

Since the gravitational force essentially involves warping space-time itself, it allows all objects to interact with each other, whether they have mass or not. For example, massless photons have been confirmed to experience the gravitational effects of astronomical objects.

“The gravitational bending of light by the set of concentric singular shells that make up a galaxy or cluster is caused by a beam of light being deflected slightly inward—that is, toward the center of a large-scale structure or set of shells—as it passes through a single shell,” notes Lieu.

“The cumulative effect of passing through many shells is a finite and measurable total deflection that mimics the presence of large amounts of dark matter in much the same way as the velocity of stellar orbits.

“Both the deflection of light and stellar orbital velocities are the only means by which to measure the strength of the gravitational field in a large-scale structure, be it a galaxy or a cluster of galaxies. I argue that at least the shells it assumes are massless. Then there is no need to maintain this seemingly endless search for dark matter.”

Questions for future research are likely to focus on how a galaxy or cluster is formed by the alignment of these envelopes, as well as how the structures evolve.

“This paper does not attempt to solve the problem of structure formation. The point of contention is whether the shells were originally planar or even straight strings, but the angular momentum winds them up. There is also the question of how to confirm or disprove the proposed shells.” Of course, the availability of a second solution, while highly suggestive, is not in itself enough to discredit the dark matter hypothesis – it could be an interesting mathematical exercise at best,” concludes Lieu.

“But it is the first evidence that gravity can exist without matter.