last week, Dark Energy Spectroscopy Instrument (DESI) has concluded its first official survey. Over the past five years, the experiment has recorded more than 47 million galaxies and 20 million stars in 11 billion years of cosmic history.
The idea of a large, important observatory completing the “last run” suggests that, as the phrase implies, experience was done. But for scientists, this could not be further from the truth. The result of a large survey is in many ways the beginning of exciting science, as hundreds of hungry scientists scrutinize the new information. This process can take anywhere from a few months to a few years – especially for data collected by an instrument as capable as DESI.
“Once you have a galaxy survey like this, it’s a real gold mine,” said a DESI co-spokesperson. Will Percival He told Gizmodo about this during a video call. “There is a lot of physics encoded in the distribution of galaxies, and there is a whole wealth of science and analysis yet to come.”
It takes a lot to explain space
If you follow cosmology, you may remember a big DESI announcement in 2025. scroll in the static cosmological constant. The research suggested that dark energy is evolving rather than fixed. According to Percival, an astrophysicist at Canada’s University of Waterloo, the finding came from studying DESI’s first three years of observations. yet investigates.
So if last year’s analysis was a small glimpse of what the DESI data can reveal, the observatory’s first completed work — the “full” data set — will surely do much more. Then again, the stakes are high. After all, the real questions here are how the universe began, how it grew, and perhaps most importantly, how it will end.
“With data as good as you get from DESI, we really need to do a careful and robust analysis,” explained Percival. Preparing the data for scientific analysis is a huge task in itself, he said, adding: “We have to do things like create mock universes and create mock catalogs of galaxies, and then look at how our observations affect the original physics (that dictate) those mock universes.”
Confirmed, but not really
This precaution ensures that the data are ready to explore ideas such as Einstein’s cosmological constant, lambda (Λ). This metric accounts for the rapid expansion of the recent universe Andrew Liddlean astrophysicist at the University of Lisbon in Portugal explained to Gizmodo. The standard cosmological model uses lambda to assume that whatever causes this acceleration — usually represented as dark energy — “maintains a perfectly constant energy density as the universe expands,” said Liddle, who is not directly affiliated with DESI.
Most observations so far have confirmed this account of the universe’s evolution, so to suggest otherwise – as DESI’s analysis in 2025 did – would be a “huge discovery that would overturn the standard model of cosmology.” Kev AbazajianAn astrophysicist at the University of California, Irvine, is also unrelated to DESI.
“However, the statistical significance of the result is not yet significant,” Abazajian said, “and it needs to be determined by an independent survey to be considered truly valid.”
“These kinds of questions really depend on how well we know the errors in the data,” Percival explained. “So we spend a lot of time making sure they’re as accurate as we can make them.”
Why do you ask such a question?
It may seem strange that if the observational results are consistent with lambda, scientists are even considering different options. This is due to the great difficulties in the theoretical side of cosmology and physics as a whole. Marina CortesAstrophysicist at the University of Portugal.
Cortes, who was involved in the earliest stages of DESI, told Gizmodo that “Lambda is so difficult to incorporate into centuries of theoretical physics that no one knows how or where to begin to change this edifice (…) due to inconsistencies that cannot be resolved by particle physics.” “Regardless of the increasing ingenuity, complexity, and concerted effort of research, the universe has remained solid (this lambda is true). This is a tug of war between the universe and established physics.”
As for the cosmological model as a whole, there are some inconsistencies related to the diversity of galaxy densities, as well as the notorious “Hubble tension” involves the expansion rate of the universe, Abazajian added.
“This is where the DESI survey plays an important role by suggesting a possible dark energy evolution,” Cortes said. “If confirmed, this provides new quantitative properties of dark energy to diagnose its true nature. Even if DESI ultimately checks (lambda) again, it will have done so with significantly higher precision…leaving lazy theorists no room to delay progress (developing new models).”
But now?
Both Abazajian and Cortês expect we’ll get some answers with DESI. EuclidAnother space telescope has been launched to investigate everything dark in the universe. The latter is scheduled to publish its first data release in October this year.
“If evolving dark energy is seen in both and with the same characteristics, it’s on its way to becoming a major discovery,” Abazajian said.
Cortês, who recently visited DESI members, told Gizmodo that the team considering the joint supernova survey Another great institution with the Rubin Observatory monster level capabilities. Other teams plans projects already in progress to both DESI and Rubin, he said.
Meanwhile, Percival told Gizmodo, the DESI team has six batches of five to ten scientific papers on various topics, all of which they plan to publish later this year. Again, this comes from DESI’s database up to its third year. It should be noted that the instrument itself has not been physically turned off and will conduct further surveys until 2028.
The team is currently working on processing the five-year data dump for scientific analysis, which Percival predicts will take about two to four months.
“And hopefully by then the team will have completed (the third-year data) and will be ready to move forward,” Percival mused. “It’s a really exciting time to be working in cosmology because we’re working with things we don’t understand. I’m biased, but I think it’s really important to get more information. This is really exciting science happening right now.”
