Largest 3D map of the universe spanning over 47 million galaxies could rewrite physics forever

From a mountaintop in Arizona, an army of robotic eyes has been peering into the deep past of the universe for the past five years. They captured ancient light that began traveling through space up to 11 billion years ago.

On Tuesday, April 14, scientists completed the main mission of the Dark Energy Spectroscopy Instrument (DESI) ahead of schedule. The team has successfully constructed the largest and highest resolution 3D map of the universe ever constructed.

The completed map illustrates more than 47 million galaxies and quasars, the ultra-bright cores of distant galaxies driven by supermassive black holes. It also includes the 20 million stars in our Milky Way.

This incredible data set represents a six-fold increase in all previous galaxy measurements combined. With such sophisticated data at hand, astronomers are preparing for a revolution in the field.

DESI found intriguing evidence that dark energy is weakening by tracking how galaxies cluster together at different times. If the final data confirm this, scientists will have to completely rewrite the Standard Model of cosmology.

“Ultimately, we are doing this for all of humanity to better understand the universe and its ultimate fate,” Stephanie Juneau, an associate astronomer at the National Science Foundation’s NOIRLab, said in a statement.

Reevaluating the expanding universe

In the late 1990s, astronomers realized that the universe was not just expanding, but that it was expanding at an accelerating rate. Some invisible force is actively pushing the galaxy outward, and it seems to be growing stronger and stronger. Scientists called this placeholder concept dark energy. Today, we know that it accounts for approximately 70% of the universe’s total matter and energy budget.

But we still don’t know what it actually is.

All along, the prevailing theory relied on Albert Einstein’s cosmological constant. In the standard model of cosmology (technically called the lambda cold dark matter (LCDM) model), dark energy describes the static energy density of empty space. It is supposed to function as a constant, unchanging force throughout the history of the universe.

But early data from DESI shows that the cosmological constant…is not constant at all. Analyzing the first few years of the study, scientists noticed that the dark energy driving force appeared to fluctuate over time.

“This is a major paradigm shift. All previous data have been compatible with the standard cosmological model, in which the accelerating expansion of the universe is driven by a cosmological constant,” Berkeley Lab DESI collaborator and scientist Nathalie Palanque-Delabreuil told science journalist Robert Lee. space dot com. “The weakening of the acceleration observed by DESI can no longer be explained by the cosmological constant. This may be the most interesting discovery in cosmology since the discovery of dark energy itself.”

“After finding hints that dark energy could deviate from the environment, [cosmological] This potentially fate-changing moment leaves you feeling on the edge of your seat as you analyze new maps to see if those hints are confirmed. We are also very intrigued by the many other discoveries that await with this new dataset,” Juneau added.

5,000-eye robotic spectrometer

How do you accurately map 47 million objects spanning billions of light years? You will build the world’s most powerful multi-object survey spectrometer.

Engineers installed DESI on the Nicholas U. Mayall 4-meter telescope at Kitt Peak National Observatory in Arizona. The device relies on 5,000 individual fiber-optic sensors.

During operation, a robotic positioner automatically aims these tiny fiber optic eyes at preselected galaxies. Once locked on, 10 giant spectrometers split the incoming light into separate colors. This process reveals each galaxy’s exact location, velocity, and physical properties.

The speed of this operation is amazing. The telescope targets a new batch of 5,000 galaxies every 20 minutes. On a clear night, the observatory can see more than 100,000 galaxies.

“We’ve been learning about this instrument for five years, and we know its character and operation pretty well. This is important because the instrument is so efficient, which is why so much good data and so much science has been published and why we’ve reached the end of DESI’s first study,” DESI co-instrument scientist Connie Roccosi, a professor at the University of California, Santa Cruz, said in a statement.

The resulting map reveals a tangled cosmic web. There is a predictable logic to how galaxies move through the universe. They clump together to form huge clusters and long glowing filaments. A vast emptiness stretches between these shining threads.

Surviving fires and pandemics

The scale of the DESI project reflects the vastness of the universe it studies. More than 900 researchers from more than 70 institutions in 14 countries collaborated on the instrument and its data.

The U.S. Department of Energy’s Lawrence Berkeley National Laboratory led the massive international effort. When the project’s main scientific expedition began in May 2021, the team aimed to map 34 million galaxies. They exceeded that goal by more than 13 million objects.

This achievement did not come easily.

“Our ability to complete the study in five years was more than a one-time feat. Everyone on the operations team worked incredibly hard to keep the study moving forward with high efficiency, and I think we’re all very proud that we were actually able to achieve this goal,” said Klaus Honscheid, principal investigator for DESI instrument operations. space dot com.

The team kept the telescope running even in the midst of a global pandemic. They also survived the devastating Contreras Fire, a massive wildfire that struck Kitt Peak Observatory in 2022 and threatened to destroy the entire facility.

Peek deeper into the web of the universe

With the completion of a major five-year mission, the team will now focus on processing huge mountains of data. The astronomical community expects the first definitive papers on dark energy to decline throughout 2027 from a five-year plan.

But the telescope hasn’t stopped.

Scientists plan to continue scanning the sky with DESI until at least 2028. The expansion will expand the space map by an additional 20%. The study expands its reach from 14,000 square degrees of the night sky to 17,000 square degrees.

This next step will see researchers push the device to its absolute limits. They plan to aim the telescope at regions obscured by nearby bright stars and peer into the southern sky through the thick layer of Earth’s atmosphere to track fainter, more distant objects.

“DESI’s five years of research have been a spectacular success,” Michael Levi, DESI director and Berkeley Lab scientist, said in a statement. “We will celebrate the completion of the first study and then begin the work of thoroughly examining the data, because everyone is interested in what new surprises await us.”

As we look at the results of 2027, one thing is clear: the universe is a much stranger place than we imagined.

“We built a great device that met all expectations and then some,” Levi said. “We’re now moving beyond our original plans. We don’t know what we’ll find, but I think it’s going to be pretty exciting.”