New theory: Gravity can exist without mass, so dark matter does not exist

For centuries, scientists have grappled with the fundamental forces that govern our universe, chief among them being gravity, and more recently, dark matter.

Gravity is the invisible force that attracts objects with mass towards each other, playing a crucial role in shaping the cosmos, from the formation of galaxies to the orbits of planets.

However, as our understanding of the universe has expanded, so too have the mysteries surrounding it.

Dark matter dilemma

One of the most perplexing of these mysteries is the concept of dark matter, a hypothetical form of matter that is believed to make up a significant portion of the universe’s total mass.

Unlike ordinary matter, which we can see and interact with directly, dark matter does not emit, absorb, or reflect light, making it invisible to telescopes and other detecting instruments.

Dark matter’s existence, first suggested by Dutch astronomer Jan Oort in 1932, is inferred solely from the gravitational effects it exerts on visible matter, such as the rotation curves of galaxies and the motion of galaxies within clusters. This leads scientists to question the very nature of gravity itself.

These observations suggest that there is far more matter present in the universe than can be accounted for by visible matter alone.

Despite decades of research, the exact nature of dark matter remains one of the greatest mysteries in modern physics, with scientists exploring various theories, such as weakly interacting massive particles (WIMPs) and axions, to explain its properties and behavior.

Ever-present force of gravity

Gravity is one of the four fundamental forces of nature, alongside electromagnetism, the strong nuclear force, and the weak nuclear force. It is the force that attracts objects with mass towards each other, and it plays a crucial role in shaping the universe at all scales.

At the Earth’s surface, gravity pulls objects towards the center of the planet, giving them weight and keeping them grounded.

On a larger scale, gravity governs the orbits of planets around the sun, the motion of stars within galaxies, and the formation and evolution of galaxies and galaxy clusters.

According to Albert Einstein’s theory of general relativity, gravity arises from the curvature of space-time caused by the presence of mass and energy. The more massive an object is, the greater its gravitational influence on other objects.

Despite its ubiquity and importance, gravity remains one of the least understood forces in physics, with ongoing research seeking to reconcile it with the principles of quantum mechanics and to explain phenomena such as dark matter and dark energy.

Seeing gravity and dark matter in a new light

Taking a fresh perspective, a recent study by Dr. Richard Lieu at The University of Alabama in Huntsville (UAH) hopes to solve the puzzle by adding a new twist to this age-old problem.

Published in the Monthly Notices of the Royal Astronomical Society, Lieu’s paper demonstrates, for the first time, how gravity can exist without mass.

This radical and thought-provoking research provides an alternative theory that could potentially mitigate the need for dark matter.

“My own inspiration came from my pursuit for another solution to the gravitational field equations of general relativity,” says Lieu, a distinguished professor of physics and astronomy at UAH.

“This initiative 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.”

Topological defects may hold the key

Lieu contends that the “excess” gravity necessary to bind a galaxy or cluster together could be due to concentric sets of shell-like topological defects in structures commonly found throughout the cosmos.

These defects were most likely created during the early universe when a cosmological phase transition occurred, a physical process where the overall state of matter changes together across the entire universe.

“It is unclear presently what precise form of phase transition in the universe could give rise to topological defects of this sort,” Lieu says.

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

Massless gravity effect resembles dark matter

The shells proposed in Lieu’s paper consist of a thin inner layer of positive mass and a thin outer layer of negative mass.

While the total mass of both layers is exactly zero, a star lying on this shell experiences a large gravitational force pulling it towards the center of the shell.

As gravitational force fundamentally involves the warping of space-time itself, it enables all objects to interact with each other, whether they have mass or not.

Massless photons, for example, have been confirmed to experience gravitational effects from astronomical objects.

“Gravitational bending of light by a set of concentric singular shells comprising a galaxy or cluster is due to a ray of light being deflected slightly inwards — that is, towards the center of the large-scale structure, or the set of shells — as it passes through one shell,” Lieu notes.

He explains that as light traverses through multiple shells, the cumulative effect results in a measurable deflection that closely resembles the gravitational influence typically attributed to the presence of a significant amount of dark matter, akin to the observed velocities of stellar orbits within galaxies.

Role of massless shells in galaxy formation

The deflection of light and stellar orbital velocities are the only means by which one gauges the strength of the gravitational field in a large-scale structure, be it a galaxy or a cluster of galaxies.

Lieu’s paper contends that the shells it posits are massless, suggesting that there may be no need to perpetuate the seemingly endless search for dark matter.

Questions for future research will likely focus on how a galaxy or cluster is formed by the alignment of these shells, as well as how the evolution of the structures takes place.

“Of course, the availability of a second solution, even if it is highly suggestive, is not by itself sufficient to discredit the dark matter hypothesis — it could be an interesting mathematical exercise at best,” Lieu concludes.

Lieu emphasizes that his research does not aim to address the issue of structure formation in the universe, and acknowledges that there are still open questions regarding the initial state of the shells and how to definitively confirm or refute their existence through targeted observations.

Despite these limitations, Lieu asserts that his work represents the first demonstration of the possibility of gravity existing without mass.

Dark matter vs. Massless gravity: Let the games begin

In summary, Dr. Richard Lieu’s fascinating research challenges the century-old notion of dark matter and offers a revolutionary perspective on the nature of gravity.

By demonstrating how gravity can exist without mass through the concept of massless shells, Lieu’s work opens up new avenues for understanding the universe and its fundamental forces.

While further investigation is necessary to confirm or refute the existence of these massless shells, this study represents a significant leap forward in our comprehension of the cosmos.

As the scientific community continues to explore the implications of Lieu’s findings, we may be on the cusp of a new era in astrophysics, one that reshapes our understanding of the mysterious force that binds galaxies and clusters together.

The full study was published in the journal Monthly Notices of the Royal Astronomical Society.

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