Astronomers have produced the largest 3D map of the universe, which can be explored in an interactive VR video. In the process, they’ve uncovered some tantalizing hints that our understanding of physics, including the ultimate fate of the cosmos, could be wrong.
The Dark Energy Spectroscopic Instrument (DESI) is a huge international project to map out the universe in three dimensions, which began collecting data in 2021. This early version of the map only includes data collected during the first year – 5.7 million galaxies and quasars out of the planned goal of 40 million. This data allows the scientists to peer as far as 11 billion light-years into deep space and time, providing a glimpse into the very early universe with an unprecedented precision of less than 1%.
With a view that zoomed-out, the cosmos resembles a colossal web, made up of bright strands of galaxies separated by unimaginably empty voids. If you feel up for an existential crisis, check out this VR fly-through video and remember that each of these blurry blobs of light is an entire galaxy, each containing millions of stars and billions of planets.
DESI isn’t just designed to make mind-boggling maps and videos though. Its purpose is to search for evidence of dark energy, the mysterious force that’s causing the expansion of the universe to accelerate. According to our current best model of cosmology – the Lambda cold dark matter (LCDM) model – dark energy constitutes 68% of the contents of the universe, but we know disturbingly little about it.
This telescope is designed to image millions of galaxies and quasars to measure their distance and speed, and with enough objects catalogued astronomers can calculate how the rate of the universe’s expansion has changed over time. That can then tell us more about the nature of dark energy at different epochs in deep time.
“No spectroscopic experiment has had this much data before, and we’re continuing to gather data from more than a million galaxies every month,” said Nathalie Palanque-Delabrouille, co-spokesperson for the experiment. “It’s astonishing that with only our first year of data, we can already measure the expansion history of our universe at seven different slices of cosmic time, each with a precision of 1-to-3%.”
Most of the analysis so far agrees with the LCDM model, which says that dark energy should remain constant throughout cosmic time. But when the team combined the DESI data with that from other studies, they found some intriguing hints that don’t quite fit with the accepted model. Galaxies closest to us didn’t seem to be moving away as fast as they should be, if dark energy was a constant. That implies its influence may be weakening over time.
If that’s the case, it could have major implications for the ultimate fate of absolutely everything. Previously, the most plausible scenario for the end of the universe was that dark energy would eventually push everything so far apart that atoms would no longer be able to group together into molecules, leaving the cosmos a cold, dark, boring place. But if dark energy is more variable, this “heat death” might not be how it all ends.
Before we get too ahead of ourselves though, it’s important to note that DESI’s data is still very preliminary. The hints haven’t been backed up with the five-sigma rigor that’s required for them to be sure it’s not a statistical anomaly. For now there’s a very good chance that these inconsistencies disappear entirely after the full five years’ worth of data is collected and analyzed.
“It’s certainly more than a curiosity,” Dr Palanque-Delabrouille told The New York Times. “I would call it a hint. Yeah, it’s not yet evidence, but it’s interesting.”
DESI is due to finish its data collecting run in 2026, and after that it may receive an upgrade to continue its work. The next few years could see scientists solve arguably the most confounding question in cosmology.
The research is available in a series of early papers on arXiv.
Source: Berkeley Lab