Dr. Richard Lieu, a physics professor at 草榴社区 (UAH), a part of The University of Alabama System, in the journal that proposes a universe built on steps of multiple singularities rather than the Big Bang alone to account for the expansion of the cosmos. The new model forgoes the need for either dark matter or dark energy as explanations for the universe鈥檚 acceleration and how structures like galaxies are generated.
The researcher鈥檚 work hypothesizing gravity can exist without mass that has garnered 41,000 reads and numerous citations since its publication in 2024.
Dr. Richard Lieu, a physics professor at 草榴社区.
Michael Mercier / UAH
鈥淭his new paper proposes an improved version of the earlier model, which is also radically different,鈥� Lieu explains. 鈥淭he new model can account for both structure formation and stability, and the key observational properties of the expansion of the universe at large, by enlisting density singularities in time that uniformly affect all space to replace conventional dark matter and dark energy.鈥�
Lieu鈥檚 improved model doesn鈥檛 rely on exotic phenomena like 鈥渘egative mass鈥� or 鈥渘egative density鈥� to work. The theory offers instead the notion that the universe is expanding due to a series of step-like bursts called 鈥渢ransient temporal singularities鈥� that flood the entire cosmos with matter and energy, yet happen so rapidly, they cannot be observed as these singularities wink in and out of existence.
鈥淪ir Fred Hoyle opposed Big Bang cosmology and postulated a 鈥榮teady state鈥� model of the universe in which matter and energy were constantly being created as the universe expands,鈥� Lieu notes. 鈥淏ut that hypothesis violates the law of mass-energy conservation. In the current theory, the conjecture is for matter and energy to appear and disappear in sudden bursts and, interestingly enough, there is no violation of conservation laws. These singularities are unobservable because they occur rarely in time and are unresolvedly fast, and that could be the reason why dark matter and dark energy have not been found. The origin of these temporal singularities is unknown 鈥� safe to say that the same is true of the moment of the Big Bang itself.鈥�
These singularities in space in lieu of dark matter also generate something called 鈥渘egative pressure,鈥� a type of energy density, like that of dark energy, that has a repulsive gravitational effect, causing the universe to expand at an accelerating rate.
鈥淎n example is the negative pressure exerted by a magnetic field along a field line,鈥� Lieu says. 鈥淓instein also postulated negative pressure in his 1917 paper on the Cosmological Constant. When positive mass-energy density is combined with negative pressure, there are some restrictions which ensure the mass-energy density remains positive with respect to any uniformly moving observer, so the negative density assumption is avoided in the new model.鈥�
The title of Lieu鈥檚 new paper 鈥� Are dark matter and dark energy omnipresent? 鈥� hints at the researcher鈥檚 ultimate conclusions: 鈥淭hey are not omnipresent 鈥� meaning, not present at all times,鈥� the researcher says. 鈥淭hey only appear in brief instances during which the matter and energy do fill the entire universe uniformly, apart from random spatial density variations which grow to form bound structures like galaxies. In between which they are not to be found anywhere. The only difference between this work and the standard model is that the temporal singularity occurred only once in the latter, but more than once in the former.鈥�
Looking to the future of his research, Lieu says the next step to validating his model of the cosmos could come through observations using earthbound instruments rather than something like the James Webb Space Telescope.
鈥淭he best way to look for the proposed effect is actually to use a large ground-based telescope 鈥� like the [Waimea, Hawaii], or the in La Palma, Spain 鈥� to perform deep field observations, the data of which would be 鈥榮liced鈥� according to redshift,鈥� the researcher notes. 鈥淕iven sufficient redshift (or, equivalently, time) resolution effected by the redshift slicing, one might just find that the Hubble diagram exhibits jumps in the redshift distance relation, which would be very revealing.鈥�