Unlocking the Mysteries of Dark Energy: Did 2024 Reveal the Secrets?

When you purchase through links on our articles, Future and its syndication affiliates may receive a commission.

The year 2024 marked a significant milestone for space science in various aspects, potentially becoming the most pivotal year for the universe’s most perplexing and enigmatic “component,” dark energy, since its identification nearly three decades prior. This was the inaugural year when researchers received an exhilarating observational clue indicating that the force propelling the accelerated expansion of the universe might be “maturing.”

Dark energy presents a substantial challenge for researchers. Constituting 68% of the universe’s overall matter-energy inventory, it is the force driving the acceleration of the expansion of the universe. This occurrence is distinct from the early inflation of the universe instigated by the Big Bang, which had nearly ceased when dark energy began to dominate!

To comprehend why this is alarming, envision pushing a child on a swing once, witnessing their motion stop, and then, inexplicably, they start swinging again, with their movement accelerating.

This late-time acceleration was identified in 1998 by two groups of astronomers measuring distances via supernovas in remote galaxies. “Dark energy” was merely a temporary label assigned to the force causing this acceleration, with the hope that eventually a more precise concept and name would be established.

Related: What is dark energy?

Despite this, dark energy has remained part of our universe’s makeup, its existence serving as a reminder that the essential component of the cosmos continues to be an enigma. You might liken this to Colonel Sanders’ secret formula of herbs and spices, except it’s more like dining at KFC without knowing what constitutes chicken or the origin of it! Quite concerning.

While 2024 did not provide a more definitive solution to this enigma than any of the preceding 25 years, a notable crack has emerged in the facade of dark energy, offering a tantalizing indication that may direct researchers toward solving this urgent cosmological conundrum.

2024 was DESI’s year

These recent dark energy indications arose from the preliminary year of data from the Dark Energy Spectroscopic Instrument (DESI), which produced one of the deepest mappings of the cosmos ever achieved.

The 5,000 robotic sensors of DESI capture light from millions of galaxies covering over a third of the sky visible from Earth, analyzing this light into a spectrum of colors. The DESI data have enabled scientists to gauge the alteration in the wavelengths of light from distant galaxies as they move away from us on the expanding fabric of space-time, a phenomenon referred to as “redshift.”

The findings from DESI provided researchers with a suggestion that dark energy is evolving over time. Notably, it seems that this enigmatic force is diminishing.

This is crucial, as in our current leading model of cosmology — the Standard Model or the Lambda Cold Dark Matter (LCDM) model — dark energy is depicted by the cosmological constant (symbolized by the Greek letter lambda). The cosmological constant is expected to remain unchanged over time in the LCDM framework.

“The unveiling of these results was a monumental occasion for cosmology, indicating a ‘decreasing’ impact of dark energy over time, suggesting it is evolving and thus, not constant after all,” said Luz Ángela García Peñaloza,

A previous DESI team participant, currently a cosmologist at the Universidad ECCI in Colombia, revealed to Space.com in April 2024 following the release of the DESI data. “If the evolution of dark energy is validated by future data, its discovery would be as groundbreaking as identifying the accelerated expansion of the universe itself.”

Space.com engaged with García Peñaloza to delve deeper into the significance of this finding and to speculate how future cosmologists might retrospectively view the year 2024.

“Up until this year, most data was aligned, suggesting that dark energy is a cosmological constant. Yet, 2024 was replete with indications that this could be incorrect,” stated García Peñaloza. “Numerous cosmic surveys have contradicted the idea of a cosmological constant and are instead providing encouraging results that point toward evolving dark energy.”

Dark energy becomes dynamic!

The suggestion that dark energy might be diminishing or transforming in any manner was a true surprise for cosmologists. As García Peñaloza highlighted, previously, observations had aligned with an “equation of state” for the universe, where the cosmological constant—and hence dark energy—remains constant over time.

García Peñaloza remarked that this deviation from past consistency “opens possibilities” for cosmological models that incorporate a type of dark energy which varies with time. This could signify the conclusion of the cosmological constant and the rise of “dynamical dark energy.”

One concept of dynamical dark energy that was endorsed by García Peñaloza even prior to the release of the DESI results was an “early dark energy” (EDE) model. This hypothesis centers around the notion that, although dark energy currently dominates the universe, it wasn’t always the scenario.

Until approximately 4 to 5 billion years ago, matter was the prevalent force in the universe, followed by radiation driving Big Bang-related inflation that had previously been supreme. EDE models propose that dark energy did not simply arise from nowhere to govern the cosmos when it was between 9 and 10 billion years old; instead, dark energy had been consistently present, playing a significant role.

This implies that it is dynamic and in flux. The initial DESI data appears to support this idea.

Related: What is the Big Bang theory?

Cosmologists will likely not be disheartened to witness the conclusion of the cosmological constant, should it be proven that dark energy is indeed evolving.

The theoretical predictions of the cosmological constant representing “vacuum energy” in space can diverge from observations by as much as 10 to the power 121 (10 followed by 120 zeroes).

It is hardly surprising that the cosmological constant has been a source of frustration for cosmologists for many years and has been labeled as “the most egregious theoretical prediction in the history of physics.”

However, let us not dismiss lambda too hastily. Additional data will be required to refute this model. And the data that could potentially do this is already on its way!

The DESI survey commenced operations from the Mayall Telescope situated atop Kitt Peak.near Tucson, Arizona, in 2021, and it is projected to function for five years, wrapping up in 2026. Excitingly, the findings we’ve already explored indicate a potential transformation for dark energy science that has emerged from just the preliminary year of outcomes.

To initiate a significant re-evaluation of dark energy, researchers will require additional data indicating that this cosmic component varies over time. Luckily, the DESI Year 2 and Year 3 information is anticipated in Spring 2025.

“Dynamical dark energy could align better with DESI Year 1 observations than the cosmological constant,” stated García Peñaloza. “That said, it is not yet definitive; they are merely suggestions leaning towards dark energy as an evolving [phenomenon] rather than the standard cosmological candidate. Nonetheless, it is quite exhilarating.

“Perhaps it is slightly premature to assert that we are uncovering this enigma, but I would argue that we now possess a deeper understanding of the behavior of this mysterious component.”

Related articles:

— ‘Astounding’ dark energy instrument findings confirm Einstein was correct about gravity — again

— In a manner, Space.com and the dark universe matured concurrently

— Dark energy might be diminishing, implying the universe could conclude in a ‘Big Crunch’

García Peñaloza elaborated on the advancements in dark energy research that she anticipates in the coming year. DESI will receive assistance in its pursuit to unveil the mysteries of dark energy, she mentioned, through additional data from the Euclid space telescope.

The European Space Agency’s (ESA’s) “dark energy investigator” was launched in July 2023, and since October that same year, it has been impressing scientists with its breathtaking images of the universe. Next year, it could replicate this with substantial data.

“Initially, Euclid will unveil the first data sets, which have been long awaited by the community. Furthermore, other measurements of the universe on large scales will publish their findings that complement the recent revelations from the James Webb Space Telescope,” concluded García Peñaloza. “The latest high-resolution numerical simulations will persist in providing new insights into what dark energy may be and likely introduce novel inquiries we are not yet aware of regarding the connection between dark energy and other cosmological phenomena.”

Like the universe itself, our enthusiasm for 2025 and the discoveries it will bring is accelerating at a rapid pace!