UC News
A swirl of clouds and and colors in a distant nebula captured by a space telescope.

Some physicists question existence of dark energy

BBC turns to UC physicist for context about one of science's big perplexing mysteries

headshot of Michael Miller By Michael Miller 513-556-6757
4 minute read October 12, 2026

BBC Science turned to a physicist at the University of Cincinnati for context about dark energy, which scientists say makes up 70% of the universe.

UC College of Arts and Sciences Assistant Professor Jessica Muir was among a group of 400 scientists from around the world who took part in the Dark Energy Survey led by the U.S. Department of Energy’s Fermi National Accelerator Laboratory.

They used powerful high-altitude telescopes to survey the night sky between 2013 and 2019, cataloguing hundreds of millions of galaxies to calculate the distribution of matter in the universe. By studying patterns of structure in the universe, researchers hope to provide some answers about dark energy. 

Not all physicists agree with the prevailing theories surrounding dark energy.

The BBC spoke to physicist David Wiltshire at the University of Canterbury, who argues that the universe isn't consistently homogeneous in every corner. He argues the clumping of galaxies might explain why the universe appears to be expanding at a faster rate since time is relative to gravity.

Portrait of Jessica Muir.

UC Assistant Professor Jessica Muir. Photo/Provided

Muir is working hard to find ways to explain the seeming paradoxes surrounding dark energy. Muir has a background in applied mathematics, earning a master’s degree from Cambridge University before she earned a doctoral degree in physics. Muir contributed to the data analysis for the Dark Energy Survey using UC’s Advanced Research Computing Center.

“There are things in our model that don’t make sense,” Muir told the BBC. “It’s not very satisfying that we don’t know what 95 per cent of the Universe is made of.”

But she told the BBC she isn't ready to dismiss dark energy and Albert Einstein's prevailing notions on the cosmological constant yet.

“It would be very exciting if we say, ‘Oh, we missed this thing, and it turns out we don’t need a mysterious substance that has negative pressure and that makes up 70 per cent of the mass and energy in the universe,'” Muir told the BBC.

Muir elaborated on her BBC interview this week.

“More excitingly, in my opinion, is that new cosmology results in the last couple years have shown a preference for time-evolving dark energy properties,“ she said.

“This would require an extension of our model of dark energy beyond the simplest 'cosmological standard model,' in which dark energy is described as a cosmological constant,“ Muir said.

“If this is the case, it would be a huge deal, but it certainly isn't a rejection of the prevailing theory of dark energy,“ she said. “It's a step towards building a more fundamental understanding of the physics of this mysterious substance that makes up 70% of the energy density in our Universe — and understanding what the available data can tell us about it.“

Featured image at top: NASA's Hubble Space Telescope captures the Tarantula Nebula. Photo/NASA

An observatory is framed by a starry sky at night.

UC Assistant Professor Jessica Muir used Chile's Cerro Tololo Inter-American Observatory to collect data for Fermilab's Dark Energy Survey. Photo/Reidar Hahn/Fermilab

Tags

Related Stories