IUB researcher co-authors ‘groundbreaking’ paper on future of the universe

The paper presents evidence that dark energy – a proposed form of energy that affects the universe – may not be a constant

Anowar Jaman Shajib, an associate member of the Center for Astronomy, Space Science and Astrophysics (CASSA) at Independent University Bangladesh (IUB), has authored a new research paper challenging assumptions about the nature of dark energy, a force that is theorised to drive the expansion of the universe.

The paper, titled “Scalar‑field dark energy models: Current and forecast constraints”, was published in the journal Physical Review D on Sept 8. Anowar, an Einstein Fellow at the University of Chicago, authored the paper alongside Joshua A Frieman, an emeritus professor at the university.

“It presents evidence suggesting that dark energy may not be a constant after all, opening up new possibilities for understanding the fate of the universe,” IBU said in a statement.

For over two decades, the dominant theory of dark energy has indicated that it is constant. But recent astronomical surveys suggest that this energy may change over time, the press release said.

“If dark energy weakens over time, it could affect the future trajectory of the universe. Instead of ending in a catastrophic ‘Big Rip’ or collapsing in a ‘Big Crunch,’ the universe may cool and fade slowly into a ‘Big Freeze’.

“If dark energy continues to grow stronger over time, then in the distant future, everything from galaxies to atoms and particles – even the fabric of space and time – will be torn apart and scattered. This catastrophic scenario is known as the Big Rip.”

The Big Crunch describes, essentially, the reverse of the Big Bang, where gravity pulls galaxies and matter towards each other, collapsing the universe into a single, dense point.

The research by Anowar and Frieman says that, if dark energy evolves very slowly, the universe will continue to expand indefinitely. If this occurs, galaxies will drift further apart, new stars will stop forming, old ones will burn out, and the universe will grow cold, dark, and inactive. The final, motionless state in which the universe may end up is called the Big Freeze, or heat death.

Anowar, who studied physics at the University of Tokyo before moving to the US to complete a PhD, explained that the paper’s model draws on a hypothetical ultra-light particle proposed in the 1970s called an axion.

“Our analysis shows that these models, where dark energy changes slowly over billions of years, fit the data better than the models where dark energy is unchanging,” he said. “The density of dark energy appears to have decreased by about 10% in recent cosmic history.”

The paper’s implications are not yet definitive, but it rules out the constant dark matter model with a 99.6 percent confidence.

“The exciting part,” said Shajib, “is that this research represents the combined knowledge of the cosmology community. We may be getting closer to answering one of cosmology’s most fundamental questions.”

Dr Khan Muhammad Bin Asad, assistant professor of Physical Sciences and founding director of CASSA, said, “CASSA is still in its early days. In many ways, it also marks the beginning of astronomy and astrophysics research in Bangladesh. As we develop our research capacity, we are building a network that includes Bangladeshi scientists working overseas as associate members. The idea is to connect local research efforts with global experience.”