Astronomers have found evidence that Earth might be located inside a massive void, a nearly 2-billion-light-year-wide gap in space. This could explain the “Hubble tension,” a long-standing disagreement over how fast the universe is expanding.
The discovery was made using sound waves from just after the Big Bang, known as baryon acoustic oscillations (BAOs). These sound waves were created when matter and radiation first cooled enough for neutral atoms to form. They act like a “standard ruler” that helps chart the cosmic expansion history.
By analyzing BAOs over 20 years, researchers found that the data supports a void model about 100 million times more likely than a void-free model. The study suggests that if Earth is near the center of a billion-light-year-wide void, it would cause matter to be pulled towards higher density regions, leading to a faster local expansion rate.
This idea could help resolve the Hubble tension, which arises from discrepancies between measurements of the universe’s expansion rates in different parts of space. The researchers propose that our galaxy is close to the center of this large void, which could shed light on the universe’s age and expansion history.
Further studies will compare this local void model with other methods, such as cosmic chronometers, which use galaxies’ redshifts to estimate their age and the universe’s expansion history.
Source: https://earthsky.org/space/earth-could-be-in-a-void-big-bang-sound-waves-hubble-tension