Ottawa physicist challenges dark matter's existence, doubles universe's age

According to the most popular theory, the universe, when simplified, consists of ordinary matter, dark matter, and dark energy, and is about 13.8 billion years old. However, a physicist from Ottawa in a new publication challenges this model. He argues that there is no place for dark matter and dark energy in space, and that the universe itself is much older.

Last year, Rajendra Gupta, a theoretical physicist from the University of Ottawa, suggested that the universe is 26.7 billion years old, not 13.8 as previously thought. This, according to him, may explain why some galaxies observed by astronomers appear surprisingly mature, although according to prevailing theories, they should have existed for only about 300 million years. Now, he has proposed an expansion of his concept, which assumes that dark matter does not exist in the universe. His study challenging the current model of the universe was published in "The Astrophysical Journal".

In cosmology, "dark matter" refers to everything that seems not to interact with light or the electromagnetic field, or can only be explained by gravity. Dark matter cannot be observed directly. We do not know what it is made of, whether it is an unknown type of particle, or waves traversing the universe. However, it is believed to be present throughout the universe.

The only evidence we have to confirm the existence of dark matter comes from various indirect proofs. Its existence is revealed by the gravitational effects it exerts, at least that's how scientists explain anomalies in the rotation of galaxies and the motion of galaxies in clusters. There is too little visible matter to explain the effects observed in these cases.

It is believed that dark matter holds galaxies together and acts like glue bonding them. Meanwhile, dark energy is thought to accelerate the expansion of the universe. In other words, leading cosmological theories treat dark matter as something that slows the expansion of the universe, and dark energy as something that constantly accelerates it. However, despite years of searching, the existence of dark matter and energy has not been confirmed.

Rajendra Gupta, a professor of physics at the University of Ottawa, in his work combined the tired light theory with one of the variations of the current model, namely the Lambda-CDM model.

The scholar merged two ideas in his work. The first, the concept of tired light, proposes that light loses energy as it traverses vast distances. This idea was suggested by Fritz Zwicky in 1929. Astronomers as far back as the 19th century noticed that light coming from a significant distance from Earth is redshifted. This phenomenon consists of a shift towards longer wavelengths of the spectral lines of electromagnetic radiation. This measurement in astrophysics is used, among other things, to estimate the age of observed objects. Light needs time to travel through space. A greater redshift effect is observed for more distant objects.

According to Zwicky, if photons lost energy over time due to collisions with other particles, more distant objects would appear redder than those closer. He admitted that any dispersion of light blurs the images of distant objects more than what can be seen. However, Zwicky's tired light concept encountered many problems and was not supported by observations, and so it remained on the fringes of astrophysics. His hypothesis competed with the currently accepted theory that the frequency shift of light towards red results from the expansion of space.

The second idea Gupta combined suggests that the forces of nature change over time. This concept was proposed by British Nobel laureate Paul Dirac. He suggested that the physical constants governing interactions between particles might evolve over time, possibly weakening. Allowing constants to evolve, the timeframes for the formation of early galaxies observed by, for example, the Webb telescope at large redshifts, can be extended from a few hundred million years to several billion years. This offers a more realistic explanation of the advanced level of development and mass observed in some ancient galaxies.

Combining these two theories, as Gupta explains, aligns with several observations, such as the dispersion of galaxies and the evolution of light from the early universe. Incidentally, it challenges the prevailing theories that indicate that only about five percent of the universe consists of ordinary, baryonic matter, and the rest is dark energy and dark matter.

“Our previous work on the age of the universe being 26.7 billion years allowed us to discover that the universe does not need dark matter to exist,” explains Gupta. “In standard cosmology, it is said that the accelerated expansion of the universe is caused by dark energy, but in reality, it is caused by the weakening of natural forces during its expansion, not dark energy,” explains the scholar.

Gupta suggests that his concept can explain fluctuations in the distribution of baryonic matter, that is, the ordinary one, caused by acoustic waves in the early history of the universe.

“There are several papers questioning the existence of dark matter, but mine is the first to eliminate its cosmological existence, while remaining consistent with key cosmological observations that have been confirmed,” says Gupta.

Gupta believes that by questioning the need for dark matter in the universe, he has provided evidence for a new cosmological model. According to him, this work opens up new possibilities for studying the fundamental properties of the universe.

Source: University of Ottawa, Science Alert