New research suggests that we may reside in a local cosmic void – a region devoid of galaxies and matter – which could explain the rapid expansion of the universe relative to the predictions of the Standard Model and provide a possible solution to the “Hubble tension mystery.”
New research suggests we may be living in a vast cosmic void – a region with far fewer galaxies and matter than expected. The finding could explain why the universe around us appears to be expanding faster than theoretical predictions – a mystery known as the Hubble Space Telescope.
New data on baryon acoustic oscillations (BAO) strengthen the possibility that we are in a local cosmic void. This finding offers a possible solution to the Hubble tension problem.
The problem of grief stress
Cosmology is currently in crisis: the local universe is expanding at a rate about 10% faster than expected. The expected rate is calculated from precise observations of the early universe and projected forward using the standard model of cosmology, called ΛCDM (cold lambda dark matter).
Acoustic oscillations of baryons represent the “sound of the Big Bang.” The early universe can be examined in great detail through the cosmic microwave background (CMB), a remnant radiation that originated when the universe was 1,100 times smaller than it is today. Sound waves traveling through the hot plasma in the early universe left behind regions of higher and lower density—that is, fluctuations in temperature.
Acoustic vibrations as a "standard marker""
These patterns, called baryon acoustic oscillations (BAOs), are also preserved in the distribution of galaxies observed today, so they can be used as a "standard ruler" for measuring distances in the universe.
When the BAO pattern appears larger in the sky at a given redshift, this indicates a faster expansion of the local universe.
Testing the hypothesis about cosmic space
Researchers Indranil Benik and Vassilaos Klaitsidis examined BAO measurements collected over the past 20 years. They compared the results to models with and without cosmic space.
In a model that includes space, the BAO "bar" should appear larger, especially at low redshift (i.e., in the local universe) – in accordance with the Hubble stress phenomenon. Observations have confirmed this prediction: the results indicate that a universe with a local space is one hundred million times more likely than a universe without space, assuming that the universe did indeed expand according to the ΛCDM model as derived from the CMB.
Significance of the findings
The researchers show that the ΛCDM model without local space is in a statistical tension of 3.8 sigma with the BAO data – a very low probability. In contrast, models that include space fit the data much better.
In the future it will be essential to make even more precise measurements of BAO at low redshift, where the effect of local space will be particularly pronounced.
The average age of the universe remains consistent with the age of ancient stars in the Milky Way, but understanding the structure of local space will contribute to resolving the crisis surrounding the Hubble tension.
The study was published in the Monthly Notices of the Royal Astronomical Society (May 2025) under the title: Testing the local void hypothesis using baryon acoustic oscillation measurements over the last 20 yr.
DOI: 10.1093/mnras/staf781
More of the topic in Hayadan:
One response
So we're at the bottom of a cosmic sound wave?