Key Takeaways:

  • Astronomers’ use of the Hubble-Lemaitre constant to explain the universe’s expansion faces challenges due to observed discrepancies, termed “Hubble tension.”
  • Researchers propose a novel solution based on recent findings suggesting our solar system resides in a region with less matter density, akin to an “air bubble in a cake.”
  • By studying the speed of nearby supernovae, scientists arrived at a different value for the Hubble-Lemaitre constant, indicating faster expansion in our vicinity.
  • This discovery potentially explains why there’s a local “under-density” in our cosmic neighborhood and challenges the current standard model of cosmology.
  • Advocating for “modified Newtonian dynamics,” researchers propose revisiting fundamental laws of gravity to reconcile the observed discrepancies and address the Hubble tension.

Delving into the Void

For nearly a century, astronomers have utilized the Hubble-Lemaitre constant to explain the expanding universe’s acceleration, a pivotal element endorsing the Big Bang theory.

To simplify, the concept suggests that the speed at which galaxies diverge from one another is directly linked to their spatial separation.

However, empirical observations have unearthed critical discrepancies, perplexing scientists. This ensuing “Hubble tension” has prompted numerous researchers to propose remedies, but so far none has been particularly satisfying to the broad scientific community.

Presently, scholars from the University of Bonn in Germany and St Andrews in Scotland assert they’ve devised a new, clever solution.

Their fresh hypothesis builds upon recent observations indicating our solar system resides in a sector with relatively little matter compared to other expanses of the known universe, analogous to an “air bubble in a cake,” as per a press release — essentially a big void where matter is significantly less dense than elsewhere in the cosmos.

Bubble Theory

The researchers reached this conclusion by studying the speed of nearby supernovae moving away from Earth. By computing their speed, the team arrived at a markedly distinct value for the Hubble-Lemaitre constant.

“Consequently, the universe appears to be expanding at a swifter pace in our vicinity — that is, up to approximately three billion light years — than in its entirety,” explained astrophysicist and University of Bonn professor Pavel Kroupa, co-author of a recent paper published in the journal Monthly Notices of the Royal Astronomical Society, in a statement.

This finding could explain why astronomers recently observed a local “under-density” in our cosmic locale.

“Hence, they are receding from us at a speed surpassing what would be anticipated,” added University of St. Andrews research fellow and co-author Indranil Banik.

Given that the current conventional model overlooks these “voids,” the researchers advocate revisiting certain fundamental principles dating back over a century.

“The conventional model hinges on Albert Einstein’s theory concerning the nature of gravity,” Kroupa noted. “Nonetheless, gravitational forces might behave dissimilarly from Einstein’s projections.”

Consequently, the team endorses “modified Newtonian dynamics,” initially posited by Israeli physicist Mordehai Milgrom in 1982.

In theory, this concept could obviate the Hubble tension altogether. However, it necessitates enduring thorough scientific scrutiny before attaining validation.

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