Einstein’s Relativity May Not Reach All Corners of the Universe. Some Say It’s a ‘Cosmic Glitch’

The scientist's theory of relativity often fails to predict motions on large scales like those of galaxies.

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Pablo Martínez-Juarez

Albert Einstein’s theory of relativity is one of humanity’s greatest advances in understanding the workings of gravity. However, some areas of our knowledge seem to escape it, places where the theoretical and the observational disagree. In other words, a “cosmic glitch” in the models.

A cosmic glitch. An international group of astronomers has detected what they call a “cosmic glitch” in Einstein's theory of relativity and its way of describing the gravitational interaction. The study, published in the Journal of Cosmology and Astroparticle Physics, also presents a way to overcome this glitch.

Extreme darkness. Relativity perfectly describes gravitational interactions in the everyday world and beyond. However, it fails at extreme scales, such as the quantum and cosmological scales.

Some of these known discrepancies include the challenge of reconciling quantum mechanics with relativity, which is seen as one of the “holy grails” of contemporary physics. Another inconsistency is the existence of unknown phenomena like dark energy and dark matter in standard models, such as the Λ-CDM model.

1%. The new research is based on studying the motion of groups of galaxies on a scale that goes beyond their internal motion. The team’s calculations suggest that gravity becomes 1% weaker on scales of billions of light-years.

“It’s almost as if gravity itself stops perfectly matching Einstein’s theory. We are calling this inconsistency a ‘cosmic glitch,’” study co-author Robin Wen noted in a recent press release.

Solving the puzzle. The study's authors believe that their failure to solve the puzzle is because they're using the wrong theoretical framework. “[It’s] like making a puzzle on the surface of a sphere, then laying the pieces on a flat table and trying to fit them together,” study co-author Niayesh Afshordi told outlet Live Science.

They argue that this failure indicates a violation of Einstein’s equivalence principle and Lorentz symmetry, suggesting that what scientists believed to be universal rules may actually be local and change at different scales.

A constant variable. The team’s hypothesis centers on the assumption that the gravitational constant isn’t actually a constant but instead decreases on a cosmic scale, resulting in a weaker gravitational interaction.

An alternative to MOND? This hypothesis shares many similarities with Modified Newtonian dynamics (MOND). This theory also aims to explain the observed shortcomings of relativity on large scales, but with a key distinction.

While the authors of the “cosmic glitch” study focus on the gravitational constant, MOND focuses on Newton’s laws of motion. MOND suggests modifying the equation that relates force to the product of mass and acceleration, which also varies with scale.

A slight tweak or a complete do-over? The cosmic glitch hypothesis is currently just that–a hypothesis. The team believes that new instruments used to study galaxies in the observable universe may one day confirm it.

However, some argue that this hypothesis may not be enough to explain the discrepancies we observe in the cosmos. As per Live Science, scientists like Scott Dodelson suggest that instead of making adjustments, we may need paradigm shifts. Perhaps this new hypothesis is just a piece in a puzzle that we’re building within a framework that doesn’t fit.

Image | Bryan Goff via Unsplash

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