Cosmology has a huge problem. It is known as hubble tension and suggests that the nearby universe is expanding faster than the distant and primitive universe He is telling us. Something does not fit. Now, a disturbing study offers a solution.
The big problem of cosmology. Hubble tension is One of the biggest headaches of modern physics. On the one hand, we have the measurements of the cosmic microwave background (CMB), the oldest light in the universe. When applying the standard cosmological model (LBDACDM), these observations show a 67.4 km/s/mpc hubble constant.
On the other hand, when The expansion of the universe is measured Using nearby objects such as standard candles (a type of supernova), a significantly higher value is obtained: about 73 km/s/mpc. This difference, that the most recent data places in a tension of more than 5Sigma (a level that in particle physics is considered a discovery), refuses to disappear.
A disturbing explanation. A new study Prepublished in Arxiv proposes a solution as elegant as depressing. That the discrepancy is not in our measurements, but in our location.
According to Indranil Cosmologists Banik and Vasileios Kalaitzidis, we could be living in the center of a gigantic cosmic vacuum, a “bubble” of 2,000 million light years in diameter with a density 20% lower than the universal average. The test, they affirm, It is in the “Big Bang sound”.
A local vacuum. The idea of the local vacuum is not new: it is known as the empty KBC (Keenan-Barger-Cowie, in honor of the astronomers who proposed the idea based on the galaxies count). If our galaxy, the Milky Way, were in a region with less matter than normal, the severity of the surrounding, densest areas, would “throw away” out.
This effect, added to the general expansion of the universe, would cause nearby galaxies to move away from us faster than normal. “This would give the appearance of a faster local expansion rate,” explains Indranil Banik, of the New Research. The Hubble tension problem would thus become a local phenomenon, without the need to revolutionize the entire cosmological model.
The sound of the Big Bang as proof. What the new study of Banik and Kalaitzidis contributes is a much more fundamental test based on barionic acoustic oscillations. Although we call them “the sound of the Big Bang”, they are not sound waves that we can hear. They are the traces that left the pressure waves that spread through the superdense plasma of the primitive universe.
These waves were “frozen” about 380,000 years after the Big Bang and created A characteristic pattern in the distribution of matter. This pattern works as a cosmic rule of about 500 million light years in length, which astronomers use to measure the expansion of the universe to different eras.
The results. The team analyzed 20 years of measurements and compared them with two scenarios: on the one hand, the homogeneous standard model, without emptiness; and on the other, the model that includes the empty KBC. The results, presented at the National Astronomy Meeting 2025 of the Astronomical Society Royal, are blunt.
According to the statistical analysis of the study, the model with a local vacuum conforms to the data in a spectacularly better way. While the standard model has a 3.3sigma voltage with observations, vacuum models reduce it to only 1.1sigma –1.4sigma.
Calmly. The researchers consider “demonstrated” that A vacuum model is about 100 million times more likely than a model without emptiness. However, it is a preliminary study, which has not yet gone through the pairs review.
Previous studies set very strict limits to the existence of such an influential vacuum, concluding that it is not enough to explain the entire Hubble tension. They also propose early dark energy as a solution. But Banik’s work offers one of the strongest evidence to date that the Earth could be in a very lonely region of the universe.
Image | Greg Rakozy (UNSPLASH)
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