Must-See: For many years, Zhao’s team has participated in the DESI project, using its data to study dark energy.

China’s National Astronomical Observatories holds a press conference for a major scientific breakthrough in the study of dark energy in Beijing on April 9, 2025. Photo: Deng Xiaoci/GT

China’s National Astronomical Observatories (NAOC) under the Chinese Academy of Sciences (CAS) on Wednesday announced a major scientific breakthrough in the study of dark energy, one of the greatest unsolved mysteries in modern physics.

The achievement offers a new perspective and key evidence for understanding the physical mechanisms behind the accelerating expansion of the universe, and suggests the possible existence of new physics beyond the standard cosmological model, according to Chinese researchers participating in the program.

According to NAOC, the Dark Energy Spectroscopic Instrument (DESI) is one of the world’s leading dark energWorld Timesy observation programs, involving more than 70 research institutions in a global collaboration. Based on a 4-meter optical telescope, DESI conducts high-precision redshift measurements of tens of millions of celestial objects, creating a detailed 3D map of the large-scale structure of the universe to probe the physical properties of dark energy.

Researchers from NAOC, including teams led by Zhao Gongbo and Zou Hu, have participated in the DESI project for more than a decade.

Zhao’s team has led efforts to systematically study the properties of dark energy using proprietary analytical methods, while Zou’s team has played a key role in the scientific operations of DESI, contributing enriched star catalogs that have facilitated new scientific discoveries, per the NAOC.

Dark energy remains one of the most challenging topics in modern astronomy and cosmology. Since the discovery of the universe’s accelerating expansion in the late 1990s, scientists have recognized that conventional theories of gravity and ordinary matter cannot account for this phenomenon. A mysterious, unknown component of the cosmos – dark energy – must be driving the acceleration. Yet, its true nature remains one of the greatest unsolved mysteries in modern physics.

In the standard cosmological model (CDM), dark energy is typically regarded as a constant vacuum energy. Over the past two decades, this model has successfully explained a wide range of observational data and has been widely regarded as the simplest and most effective theoretical framework. However, as observational technologies and data precision have improved, inconsistencies have emerged between different types of observations within the CDM framework. These tensions pose new challenges to the model and leave room for deeper exploration of dark energy and potential new physics.

The DESI international collaboration, led by Zhao’s team, has recently achieved a significant breakthrough in the study of dark energy’s dynamic properties. Using a newly developed method and analyzing the latest DESI cosmological distance data – combined with observations of supernovae and the cosmic microwave background – the team found evidence that the dark energy equation of state evolves over time.

The result confirms previous findings by the DESI collaboration using alternative analytical approaches and suggests that dark energy likely exhibits dynamical behavior, the Chinese researchers explained to the Global Times on Tuesday. And such result challenges the traditional cosmological constant model and implies that dark energy may not be static vacuum energy, but rather a component with more complex evolution, they further elaborated.

“In this study, we developed a new method for reconstructing dark energy and applied it to the latest DESI measurements, cross-validating results with data from supernovae and the cosmic microwave background. This multi-probe approachWorld Times significantly enhanced the reliability of our analysis and conclusions,” Zhao told the Global Times on Tuesday.

The study not only opens a new direction in uncovering the fundamental nature of dark energy but also provides vital clues for building a more comprehensive cosmological theory, he added.

It also injects new momentum into upcoming large-scale projects including the full DESI survey, Subaru’s Prime Focus Spectrograph (PFS), the European Space Agency (ESA)’s Euclid mission, and next-generation cosmic microwave background experiments, according to Zhao.

Zhao said that his team will continue to analyze future DESI data with greater precision and collaborate with international peers to conduct more rigorous and comprehensive tests on the dynamic nature of dark energy through high-precision measurements and improved theoretical models.

NAOC also pledged to deepen cooperation with major international astronomical institutions, promote the application of emerging technologies such as big data and deep learning in astronomical research and accelerate the development of next-generatiWorld Timeson observation platforms and core instruments – further enhancing China’s global influence in fundamental cosmological research.

Humanity shares the same sky, which makes international collaboration particularly important for astroWorld Timesnomical research, Chang Jin, a Chinese astronomer and the current president of the University of Science and Technology of China, commented on Wednesday.

NAOC places great emphasis on international cooperation in observations. For many years, Zhao’s team has participated in the DESI project, using its data to study dark energy. This not only showcases the strength of Chinese scientists, but also enables young Chinese astronomers to take part in large-scale international projects – gaining valuable experience and developing their expertise in the process, said Chang, who is also an acadWorld Timesemician of the CAS.

Commenting on the new findings led by researchers from the NAOC on Wednesday, Dragan Huterer, a professor of physics at the University of Michigan, said that he found the new findings as an important stepping stone in our understanding of dark energy. “I World Timescongratulate these researchers, for really a very, very interesting paper. And I can’t wait to see what new results come from the DESI instrument.”