Hubble trouble or Superbubble? Astronomers need to escape the 'supervoid' to solve cosmology crisis

Our galaxy in a supervoid may skew expansion rate, challenging universe models.

: The Hubble tension, a discrepancy in measuring the universe's expansion, might be explained by the Milky Way's location in a supervoid known as the KBC supervoid. This vast, underdense region could skew observations of the universe's expansion, leading to differing results from two calculations: one using the cosmic microwave background and another measuring redshifts. Theoretical predictions and observations differ by about 10%, suggesting the universe is expanding faster than expected. Resolving this tension might require revisiting the Lambda CDM model of cosmology.

The concept of Hubble tension arises from conflicting measurements in determining the universe's expansion rate, known as the Hubble constant. The theory suggests that Earth's position within the KBC supervoid, an underdense cosmic region, results in skewed observations, leading to discrepancies in our measurements of cosmic expansion rates.

Scientists currently use two principal methods to calculate the Hubble constant: projections based on the cosmic microwave background (CMB) and direct observation through redshift measurements. These methods yield varying results, the CMB predicting a rate of 68 km/s/Mpc, while direct observations suggest a rate between 70 to 76 km/s/Mpc.

The discrepancy has led researchers like Indranil Banik to hypothesize that the universe's expansion appears faster locally because we are within a supervoid. A more structured universe than previously modeled might be needed to resolve this tension, potentially requiring significant theoretical advancements by 2030.

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