The Standard Cosmology Model May Be Breaking
A recent study at the American Physical Society’s Global Physics Summit has announced that dark energy, the mysterious force driving the universe’s expansion, may be changing over time. This finding could challenge the conventional model of cosmology known as ΛCDM and raise questions about the fate of the universe.
Researchers from the Dark Energy Spectroscopy Instrument (DESI) analyzed data from 15 million galaxies and quasars to determine the distances between them. They used a “standard ruler” called the baryon acoustic oscillation scale, which can be measured at every epoch going back 11 billion years. By tracking how this ruler changes over time, scientists can estimate the expansion history of the universe.
The current understanding of the universe’s expansion is based on the ΛCDM model, which includes dark matter and ordinary matter, along with a simplified version of dark energy called the cosmological constant. However, DESI’s findings suggest that this picture may not be supported by observational data. The researchers found that the density of dark energy is evolving in ways that contradict the ΛCDM model.
The study’s lead author, Enrique Paillas, stated that the new data favors a time-evolving (or dynamical) dark energy model, which would have significant implications for our understanding of the universe’s fate and the unification of gravity with quantum mechanics.
The DESI analysis also reveals that dark energy is evolving in ways that were not expected. The ratio of pressure to energy density, called w, is fixed at -1 in the ΛCDM model, but in the DESI study, its value was around -1.4 billion years ago and has decreased since then.
Cosmologists are excited about the findings, with some hailing them as a major breakthrough. Harvard string theorist Cumrun Vafa stated that the results align well with his team’s hypothesis, which suggests that dark energy evolves at a rate proportional to its strength.
However, not all experts are convinced. Cosmologist Rocky Kolb maintained some skepticism, citing a lack of compelling theoretical reasons for dynamical dark energy.
Overall, the DESI study presents a significant challenge to our current understanding of the universe’s expansion model and raises new questions about the nature of dark energy.
Source: https://physics.aps.org/articles/v18/72