Black Holes and Dark Energy May be Connected, as Potential Link Emerges Between Two Cosmic Mysteries

New research proposes a profound connection between two of the universe’s greatest mysteries: black holes and dark energy.

According to a recent paper by an international research team, dark energy—the mysterious force that constitutes about 70% of the universe—may be a byproduct of black hole formation.

The Question of Dark Energy

“If you ask yourself the question, ‘Where in the later universe do we see gravity as strong as it was at the beginning of the universe?’ the answer is at the center of black holes,” explained study co-author Gregory Tarlé. “It’s possible that what happened during inflation runs in reverse, the matter of a massive star becomes dark energy again during gravitational collapse—like a little Big Bang played in reverse.”

To explore this theory, scientists from five institutions collaborated using the Dark Energy Spectroscopic Instrument (DESI). Located 6,880 feet above sea level on the Mayall telescope in the Sonoran Desert near Tucson, Arizona, DESI was completed in 2019 and began operating in 2020. Its five thousand fiber-optic robotic sensors are designed to scan the skies for dark energy, observing millions of distant galaxies and quasars.

The data gathered by DESI offered a glimpse into the universe as it appeared billions of years ago, given the immense distance light must travel to reach us. Despite the vast scales involved, DESI provided precise measurements, enabling researchers to calculate the universe’s expansion rate with remarkable accuracy. By tracking this expansion, the team estimated the quantity of dark energy and compared it to the formation of black holes from stellar collapse across cosmic time.

“If black holes contain dark energy, they can couple to and grow with the expanding universe, causing its growth to accelerate,” noted lead author Kevin Croker of Arizona State University.

black Holes and Dark Energy Linked?

Not everyone was immediately convinced of a connection. “When I first got involved with the project, I was very skeptical,” admitted co-author Steve Ahlen of Boston University. “But I maintained an open mind throughout the entire process, and when we started doing the cosmology calculations, I said, ‘Well, this is a really nice mechanism for making dark energy.'”

The analysis suggested a link between dark energy and black hole formation, indicating that baryons might convert to dark matter during black hole birth. This finding potentially addresses several longstanding cosmic mysteries; for instance, it suggests that dark energy’s prevalence has grown over time, linked to the formation of stars. Dark energy, the researchers propose, originates from matter itself, a relationship that could explain why it appears on the same order of magnitude as the universe’s matter content.

This connection may also clarify why the universe contains fewer baryons—fundamental particles like protons and neutrons—than anticipated, as they are thought to be consumed in creating black holes. Furthermore, scientists propose that the conversion of baryons into dark energy may account for the universe’s accelerated expansion, surpassing predictions based on Cosmic Background Radiation. This transformation, they argue, resulted in an earlier-than-expected shift, positioning dark energy as the dominant cosmic component.

“The two phenomena were consistent with each other—as new black holes were made in the deaths of massive stars, the amount of dark energy in the universe increased in the right way,” commented co-author Duncan Farah of the University of Hawaii. “This makes it more plausible that black holes are the source of dark energy.”

Younger Black Holes and Their Implications

A key difference in the DESI data lies in the age of the black holes studied. Unlike prior studies, which focused on ancient black holes, the black holes in this research are comparatively young, formed in a universe where star formation was already well underway.

“This occurs much later in the universe and is informed by recent measurements of black hole production and growth as observed with the Hubble and Webb space telescopes,” said co-author Rogier Windhorst of Arizona State University and the James Webb Space Telescope.

Future Directions

“The next question is where these black holes are and how they have been moving around for the past 8 billion years. Scientists are working to constrain this right now,” Croker said.

With DESI producing an unprecedented depth of data on black holes and dark energy, the team anticipates groundbreaking insights in the near future. As they describe it, these findings represent a “sea change” in our understanding of cosmic forces.

“Fundamentally, whether black holes are dark energy, coupled to the universe they inhabit, has ceased to be just a theoretical question,” Tarlé concluded. “This is an experimental question now.”