Expansion of the universe may be an illusion, study points out – 7/3/2023 – Science

The expansion of the universe may be an illusion, according to a study recently published in the scientific journal Classical and Quantum Gravity.

Such an innovative approach could also shed light on the enigmas of dark energy and dark matter, which scientists say make up about 95% of the universe’s total energy and matter.

The new approach was presented by Professor of Theoretical Physics Lucas Lombriser, from the University of Geneva, in an article released in June.

Expansion of the universe and the cosmological constant

According to the scientific news portal live Sciencescientists know that the universe is expanding because of the so-called redshift, that is, an increase in the wavelength of light towards the redder end of the spectrum as the object that emits light moves away from us.

Distant galaxies have a greater redshift than those closer to Earth, which suggests that they are moving further and further away from our planet.

Recently, scientists discovered that the expansion of the universe is not constant, but is accelerating more and more. This acceleration is attributed to the so-called cosmological constant or lambda. However, since Albert Einstein described such a constant more than 100 years ago, it has been a challenge for cosmologists, as theoretical predictions differ greatly from actual observations, leading them to propose new particles or forces to explain such a discrepancy. .

New hypothesis on the accelerated expansion of the universe

Rather than proposing new particles or physical forces, Lombriser suggests rethinking what is already known. In an interview with live science about his new study, the astrophysicist said that his new hypothesis involves a new look at the long-established theory of the accelerated expansion of the universe.

“In this work, we put on a new pair of glasses to observe the cosmos and its undeciphered enigmas, performing a mathematical transformation of the physical laws that govern it”, said Lombriser.

“I was surprised that the cosmological constant problem just seems to disappear in this new perspective on the cosmos.”

flat and static universe

In Lombriser’s mathematical interpretation, the universe is not expanding but is flat and static, as Albert Einstein initially proposed, before the introduction of the idea of ​​the cosmological constant.

According to the astrophysicist, the effects that we observed that point to an expansion are explained by the evolution of the mass of particles, such as protons and electrons, over time.

In this scenario, these particles arise from a field that permeates spacetime. The cosmological constant is defined by the mass of the field, and as this field fluctuates, the masses of the particles it generates fluctuate as well. The cosmological constant still varies with time, but in this model, this variation is due to the changing mass of particles over time, not the expansion of the universe.

Regarding dark matter, which cannot be directly observed, Lombriser’s study suggests that this mysterious material could behave like an axion field, a hypothetical particle that is considered one of the main candidates to explain dark matter.

Furthermore, fluctuations in this field could mean that dark energy, the mysterious force responsible for the accelerated separation of galaxies, is not needed, Lombriser told the live Science.

Promising approach, but difficult to verify

While the proposed approach may be promising for addressing the challenges associated with the cosmological constant, physicist Luz Ángela García, a researcher at ECCI University in Bogotá, cautions that caution is needed when evaluating the paper’s conclusions.

To Live Science, she said that the new theoretical model contains elements that probably cannot be verified observationally, at least not in the near future.