A “cosmic glitch” in the universe forces astronomers to rethink Einstein's theory of relativity

Over the past 100 years, countless studies have proven that Albert Einstein's greatest theory—his general theory of relativity—is virtually bulletproof, capable of everything from predicting the behavior of black holes to controlling GPS technology.

However, as scientists arm themselves with increasingly powerful and sophisticated technologies that can peer into space in unprecedented detail, they are observing phenomena that Einstein's theory cannot explain.

Einstein's general theory of relativity states that the curvature of space-time causes gravity. But as the scale increases, for example, galaxy clusters stretching over billions of light years, the laws of gravity theory change.

“It’s as if gravity itself is no longer perfectly aligned with Einstein’s theory,” says Robin Wen, a recent graduate of the University of Waterloo, in press release university.

Wen is part of a joint working group between the University of Waterloo and the University of British Columbia that is trying to solve this mystery, calling the discrepancy in Einstein's theory a “cosmic glitch.”

Their new study, published in the peer-reviewed Journal of Cosmology and Astroparticle Physics, suggests that gravity becomes about 1% weaker at very large scales. If gravity behaved according to Einstein's theory, then this 1% difference should not exist.

Cosmologists have no plans to abandon general relativity anytime soon. It remains a strikingly accurate basis for understanding gravity at small scales.

“We're not disrupting GPS or the black hole. We were just trying to understand if there were any abnormalities at the largest scales,” Wen told Business Insider.

If this glitch really exists, it could help cosmologists explain some of the universe's greatest mysteries.

Easing cosmological tension

The research team was looking at data on the cosmic microwave background when they discovered this apparent glitch.

Cosmic RI is a huge long-lasting radiation scattered throughout space, left over after the Big Bang. Scientists use it to understand the earliest stages of the universe, such as how the first galaxies formed and what happened immediately after the Big Bang.

Wen and his colleagues used a model based on fundamental physical laws, such as Einstein's general theory of relativity, and compared the model's predictions of what the CMB data should look like with data from actual CMB observations.

Their scientific model did not match observations – what we see in the distant Universe.

However, when they tweaked Einstein's theory to account for the 1% gravitational deficit, their model began to fit the observational data more closely, Wen told BI in an email interview.

A 1% adjustment may seem insignificant, but it is enough to suggest that Einstein's theory needs to be rethought. Moreover, this glitch may help us better understand some of the strange behavior of the Universe.

Space, as we understand it, is full of contradictions. Sometimes different measurements of the same phenomenon do not agree with each other. One example of such a phenomenon is the Hubble tension, a problem that has puzzled astronomers for many years.

The Hubble tension refers to inconsistent measurements of the expansion rate of the Universe. According to our standard model of physics, the expansion rate of the universe should be the same everywhere. However, observations of the nearby Universe show that the expansion rate here is higher than in regions of the distant Universe. Astronomers have proposed many possible explanations, but have not yet reached a consensus.

Now, after studying this “cosmic glitch,” a new explanation has emerged.

Attenuating gravity by 1% at large scales could reduce the Hubble tension, bringing the expansion rate of the universe closer to local observations, Nyaesh Afshordi, study co-author and professor of astrophysics at the University of Waterloo, said in a recent YouTube interview.

Thinking outside the box

The fact that this cosmic glitch could potentially help astronomers solve the Hubble tension problem is a good sign that it might actually exist. But this study is not definitive proof of a 1% gravity deficit at large scales, Wen says.

There is still a possibility that this failure may be the result of a statistical error. “With future data in the next 10 years, we should see whether this is a real detection or just a fluctuation due to statistical processing of the data,” Wen said.

Valerio Faraoni, professor of physics and interim dean of the Faculty of Science at Bishop University, told BI that it is reasonable to think the glitch may exist because general relativity has not been tested in the distant universe.

So “it's entirely possible, at least in principle, that we don't understand gravity at large scales,” said Faraoni, who was not involved in the study.

He believes that to resolve contradictions between predictions and observations of our Universe, we need to think outside the box. And this study of the “cosmic glitch” is aimed at just that.

“We probably need something outrageous,” he said. “It does look exotic, it does look strange. But I think we should be absolutely open to all these strange ideas.”

Next, Wen and his colleagues will take a close look at new data obtained from the Dark Energy Spectroscopic Instrument (DESI). DESI measures the influence of dark energy on the rate of expansion of the Universe and creates the largest 3D map of the cosmos to date.

DESI also found that dark energy, like gravity, behaves differently than astronomers expect on large cosmological scales. Wen wants to find out whether these two “glitches” are related, which would serve as further evidence that general relativity needs to be adjusted.

But even he is skeptical about the limitations of general relativity. “If you asked me to bet, I would bet on general relativity. Because general relativity works so well, right? As for alternative models, it's hard to say anything about them at this stage,” he says.