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Recent results of research by scientists using the Dark Energy Spectroscopic Instrument (DESI) spectroscope to study dark energy indicate that this mysterious power can change, which challenges standard models of the universe.
Although researchers are still working to confirm the results, the indications are that dark energy may change over time. Dark energy represents one of the key secrets for modern cosmology. Scientists know that it exists because they observe the accelerated expansion of the Universe, but they cannot explain what this dark energy is.
Using the new Aurora
«If the DESI result is confirmed, it will mean that the cosmological constant is not a source of cosmic acceleration. This would mean that space is filled with dynamically evolving matter with negative gravity, which has never been observed in any experiment on Earth», — explains physicist at the Argonne National Laboratory of the US Department of Energy Andrew Hearin.
For support in conducting research Hirin and his colleagues turned to the Aurora supercomputer. With its help, they conducted large-scale modeling Universe to analyze DESI data.
DESI collects spectra of light from distant galaxies to determine their structure, distances, and motion. During its first year of operation, this spectrograph helped scientists create the most detailed three-dimensional map of the Universe and track its expansion over the past 11 billion years. Initially, the data obtained with DESI were consistent with the standard model of cosmology. However, minor differences may indicate that dark energy can change over time. It is challenges current theory cosmic acceleration — cosmological constant.
It was first added to his equations of general relativity by Albert Einstein in 1917. The cosmological constant was supposed to counteract gravitational collapse, supporting the idea of a static universe. However, the discovery about a decade later that the Universe is expanding forced scientists to abandon this idea.
Comparing two models of the Universe, similar to each other at the beginning, but with different properties of dark energy, where in one model dark energy is constant and in the other — dynamic, scientists compared the results of both simulations with data obtained from DESI, determining which of these models most closely matches real-world observations.
«The idea is that you create a model of the universe with one set of assumptions and then compare your model of the universe to the real universe. If the agreement is sufficient, it gives you some confidence that your assumptions are correct. But if you have some kind of gross mismatch, it means that your assumptions don’t match the real universe and don’t reflect the truth», — Andrew Hearin explains.
Although the simulations cannot directly confirm the conclusions based on the DESI results, they provide critical feedback between theory and observations.
«If looking at these two simulations gives us an idea of the type of measurement we need to make to narrow down the field to a cosmological model, then we can go back to the real DESI data, make the same measurement, and see what it tells us», — notes the researcher University of Argonne Gillian Belz-Mormann.
The results of the research were published on the preprint server Arxiv
Source: SciTechDaily