New DESI data challenges understanding of dark energy's nature

The latest data from the Dark Energy Spectroscopic Instrument (DESI) indicate that dark energy may not be constant. This mysterious force is responsible for the accelerating expansion of the universe, ensuring the balance of the ever-growing cosmos.

DESI, located at the Kitt Peak National Observatory in Arizona, involves an international collaboration of over 900 scientists. During its first year of operation, DESI created the most accurate 3D map of the universe, allowing for tracking its expansion over the past 11 billion years. The device collects light from over 30 million galaxies and breaks it down into spectra, analysing the colours of light. Based on this, it can determine the so-called redshift, which indicates how much galaxies have moved away from Earth, allowing scientists to ascertain their age and position in the universe's history.

To explore these discoveries, scientists from Argonne National Laboratory used the supercomputer Aurora to simulate the universe. These simulations enable the testing of different scenarios and assist in analysing data from DESI.

One of the key challenges in cosmology is distinguishing real patterns in the data from distortions arising from data collection and analysis methods. Simulations provide a controlled environment for testing various theories.

Dark energy is a hypothetical form of energy responsible for the universe's accelerating expansion. It accounts for about 68-70% of the universe's total energy, but it does not emit, absorb, or reflect light.

Simulations conducted by the Argonne team enable rapid responses to new discoveries in cosmology. Thanks to these simulations, scientists can better discern whether observed patterns are results of new physical phenomena or are due to systematic errors.