Scientists have questioned the persistence of dark energy in the universe

Scientists continue to look for an explanation for the accelerated expansion of the universe, which is associated with dark energy. In the standard cosmological model, its properties are considered unchanged, but new observations force us to verify this assumption. By combining data on almost three thousand supernovae, the researchers found additional signs of possible changes in dark energy over time. See the Izvestia article about why observations of exploding stars can change our understanding of the universe.

What was shown by almost three thousand supernovae

An international team led by scientists from the University of Queensland's School of Mathematics and Physics has combined observations of 2,884 Type Ia supernovae. These white dwarf explosions are used to measure distances in space and study the history of the expansion of the universe. The consolidated database combines data collected over 30 years.

According to graduate student Ryan Camilleri, the work made it possible to bring many years of astronomical observations into a single system and get the most detailed picture of the changes in cosmic expansion. The researchers also compared data on supernovae with other cosmological measurements, including the cosmic microwave background radiation from the Big Bang and maps of the distribution of galaxies.

According to him, the results not only confirm the standard cosmological model, in which dark energy is considered constant and unchanging, but also provide additional grounds to assume that its properties may change over time. The work was published in the journal Science Daily.

How scientists combined old observations

The new database includes historical measurements of supernovae and the results of the Dark Energy Survey (DES) project, published in 2024. In order for the data obtained in different years to be correctly compared, the researchers reanalyzed previous observations using updated processing methods.

The scientists took into account that the telescopes used to collect the data vary in their capabilities. The measurements are also influenced by cosmic dust and the mass of galaxies, which can alter the light of distant supernovae. In addition, the researchers included gravitational lensing in the analysis — the bending and amplification of light under the influence of gravity of massive objects on the way from the supernova to the Earth.

Camilleri noted that over the years, scientists have learned more about the behavior of supernovae and have been able to apply this knowledge to earlier observations. This has improved the consistency and accuracy of measurements collected over several decades.

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Why is dark energy in question?

In the standard cosmological model, dark energy is considered as a permanent characteristic of the universe. However, the results of supernova observations in 2024 have already indicated possible changes in its properties. The new combined database also showed a deviation from the standard model, albeit in a slightly different direction.

Astrophysicist Tamara Davis noted that additional interest in the results is related to data from another independent project, the Dark Energy Spectroscopic Instrument (DESI). He studies the relic sound waves of the early universe, and his results also contain signs of possible changes in dark energy.

The researcher emphasized that two independent sets of measurements indicate the possible variability of dark energy. However, the results do not match the exact nature of the deviation from the standard model. Therefore, they provide grounds for further testing of the hypothesis, but do not mean that the variability of dark energy has already been proven.

What observations will help to test the hypothesis?

The researchers plan to expand the database as new data becomes available. One of the sources is the Dark Energy Bedrock All—Sky Supernova (DEBASS) program, which detects hundreds of supernovae at shorter distances from Earth than objects studied as part of the Dark Energy Survey. The new observations will allow us to supplement the measurements and verify whether dark energy really changes as the universe evolves.

The study of dark energy may have implications for other issues of theoretical physics. According to Davis, these studies can potentially help figure out how to reconcile gravity with quantum physics. The work offers new evidence in favor of the possible variability of dark energy, but a final conclusion will require further observations and verification of the results.