Importance Score: 75 / 100 🔴
Fresh indications from a comprehensive cosmic survey suggest that enigmatic dark energy might be changing, potentially altering current astronomy understandings of the universe. The Dark Energy Spectroscopic Instrument (DESI) collaboration’s latest data indicates this mysterious force, believed to drive the accelerating expansion of the cosmos, may not be constant as previously thought.
Unraveling the Mystery of Dark Energy
Dark energy, a term employed by scientists to define an energy or force propelling the universe’s accelerating expansion, constitutes approximately 70% of the cosmos’ total energy. Despite its prevalence, its precise nature remains unknown, according to Mustapha Ishak-Boushaki, a physics and astrophysics professor at the University of Texas at Dallas.
Ishak-Boushaki co-chairs a working group for the DESI project. This instrument, currently in its fourth year of sky observation, is capable of simultaneously capturing light from 5,000 galaxies. Upon the project’s completion next year, it will have scrutinized the light emanating from roughly 50 million galaxies.
The DESI collaboration, encompassing over 900 researchers, released its most recent data findings on March 19, derived from the instrument’s initial three years of observation. The data incorporates measurements of nearly 15 million galaxies and quasars, among the most luminous objects in the universe. Ishak-Boushaki played a key role in analyzing this recent data release, which proposes that dark energy, traditionally considered a static “cosmological constant,” may be exhibiting dynamic behavior, possibly diminishing in strength over time.
“The discovery of dark energy nearly three decades ago was already the biggest surprise of my scientific career,” stated David Weinberg, an astronomy professor at The Ohio State University involved in the DESI analysis. “These new measurements present the most compelling evidence to date suggesting dark energy evolves, a potentially revolutionary shift in our comprehension of the universe’s workings.”
These findings bring astronomers closer to deciphering the enigmatic nature of dark energy, potentially necessitating revisions to the standard model of the universe, scientists suggest.
DESI: A Deep Dive into the Cosmos
The Dark Energy Spectroscopic Instrument is situated at the Nicholas U. Mayall 4-meter Telescope of the National Science Foundation, located at Kitt Peak National Observatory in Tucson, Arizona. DESI’s array of 5,000 fiber-optic “eyes” and extensive survey capabilities are enabling scientists to construct one of the largest 3D maps of the universe and trace dark energy’s influence on the cosmos across the past 11 billion years.
Time-Traveling Through Light
Light from distant celestial bodies, such as galaxies, requires considerable time to reach Earth. This temporal aspect allows DESI to effectively observe the cosmos as it existed at various epochs, spanning billions of years into the past to the present day.
“DESI’s capacity to simultaneously observe numerous independent objects is unparalleled,” noted John Moustakas, a physics professor at Siena College and co-lead of the data release.
The latest results incorporate data from more than twice the number of cosmic objects surveyed in the previous data release less than a year prior. These earlier findings initially hinted at the potential evolution of dark energy.
“We are allowing the universe to reveal its mechanisms, and it might be indicating a complexity exceeding our prior assumptions,” commented Andrei Cuceu, a postdoctoral researcher at Lawrence Berkeley National Laboratory, which manages DESI, and co-chair of DESI’s Lyman-alpha working group. “The consistency across multiple lines of evidence is compelling and bolsters our confidence in this direction.”
Accumulating Cosmic Evidence
DESI can measure the baryon acoustic oscillation (BAO) scale, a crucial cosmological yardstick. BAO reflects patterns imprinted on the distribution of matter throughout the universe originating from early cosmic events. Astronomers utilize the BAO scale, characterized by matter separations of roughly 480 million light-years, as a standard measure of cosmic distance.
“This separation scale acts as a colossal ruler in space, enabling us to gauge distances. We then combine these distance measurements with redshifts—the velocities at which objects recede from us—to quantify the universe’s expansion,” explained Paul Martini, an analysis coordinator and astronomy professor at The Ohio State University.
Assessing dark energy’s influence throughout cosmic history demonstrates its significance as a dominant force.
When researchers integrated DESI observations with other cosmic light measurements, such as exploding stars, gravitationally lensed light from distant galaxies, and the cosmic microwave background—the afterglow of the early universe—the data suggested a possible weakening of dark energy’s influence over time.
“If this trend persists, dark energy may eventually cease to be the prevailing force in the universe,” Ishak-Boushak stated. “Consequently, the universe’s expansion will cease accelerating, potentially reaching a constant rate, or even, in certain models, halting and reversing into collapse. While these scenarios are far in the future, unfolding over billions of years, the mounting evidence for evolving dark energy, if sustained, represents a monumental shift for cosmology and physics as a whole. My 25 years investigating cosmic acceleration leads me to believe these findings hold profound implications.”
Towards Solving a Cosmic Puzzle
Definitive proof of evolving and weakening dark energy remains forthcoming; however, a breakthrough discovery could materialize within the next few years, according to Ishak-Boushak.
“My primary question is whether we will observe continued evidence for evolving dark energy as our measurements refine,” Martini stated. “Should the evidence become overwhelming, my subsequent inquiries will center on the nature of dark energy’s evolution and the most plausible physical explanations.”
The recent data release may also provide insights into the evolution of galaxies and black holes, as well as the nature of dark matter. Although undetected to date, dark matter is theorized to constitute 85% of the universe’s total matter.
Scientists involved in the DESI collaboration are eager to enhance their measurements utilizing the instrument.
“The essence of dark energy, whatever it may be, will dictate the future trajectory of our universe,” remarked Michael Levi, DESI director and a scientist at Lawrence Berkeley National Laboratory. “It is truly remarkable that we can observe the sky with telescopes and endeavor to answer one of humanity’s most fundamental questions.”
Future experiments, such as Spec-S5 (Stage 5 Spectroscopic Experiment), are being planned to survey ten times more galaxies than DESI to further probe dark energy and dark matter, according to Martini.
“Spec-S5, employing telescopes in both hemispheres, would comprehensively map galaxies across the entire sky,” Martini explained. “We also anticipate valuable data from the Vera Rubin telescope’s supernova studies, offering a novel, uniform dataset for investigating the universe’s expansion history.”
Space-based observatories like the Euclid space telescope and the Nancy Grace Roman Space Telescope, slated for launch by 2027, will further contribute critical measurements of dark matter and dark energy in the coming years, potentially resolving existing knowledge gaps, noted Jason Rhodes, an observational cosmologist at NASA’s Jet Propulsion Laboratory. Rhodes, while not associated with DESI, is the US science lead for Euclid and principal investigator for NASA’s Euclid dark energy science team.
Rhodes described the DESI results as intriguing, highlighting a subtle but persistent discrepancy between measurements from the early and later universe.
“This tension implies that our simplest dark energy model is insufficient to reconcile the observed early universe with the late universe,” Rhodes explained. “DESI and other recent findings suggest a preference for a more complex dark energy model. This is genuinely exciting as it may indicate novel, undiscovered physics governing the universe’s evolution. DESI has provided tantalizing clues potentially signaling the need for a revised cosmological model.”