New observations from the James Webb Space Telescope (JWST) delve into a mystery that has puzzled cosmologists for more than a decade: the so-called Hubble tension, which refers to the discrepancy between measurements of the universe’s current expansion rate and predictions based on standard cosmological models.

These findings suggest that the faster expansion of the universe today compared to its early stages, billions of years ago, might be due to an unknown feature of the universe rather than errors in measurement instruments.

JWST data corroborates previous measurements from the Hubble Space Telescope, strengthening confidence in the methods used to determine the Hubble constant, a value that describes the speed at which the universe is expanding. These measurements have proven crucial in addressing the discrepancy between observed values and theoretical predictions.

Universe expansion
A representation of the evolution of the universe over 13.77 billion years. The far left depicts the earliest moment we can now probe, when a period of “inflation” produced a burst of exponential growth in the universe. (Size is depicted by the vertical extent of the grid in this graphic.) For the next several billion years, the expansion of the universe gradually slowed down as the matter in the universe pulled on itself via gravity. More recently, the expansion has begun to speed up again as the repulsive effects of dark energy have come to dominate the expansion of the universe. Credit: NASA / Goddard Space Flight Center

The team led by Nobel laureate Adam Riess employed three different methods to measure galactic distances, using data collected by both telescopes. The results show remarkable consistency, with differences of less than 2% between measurements. This virtually rules out the possibility that the discrepancy in the Hubble constant values is due to errors in the Hubble telescope’s observations.

Despite this precision, a substantial difference persists between observations and predictions from the standard cosmological model. This model, based on data from the cosmic microwave background — the leftover radiation from the Big Bang — suggests a Hubble constant value of between 67 and 68 kilometers per second per megaparsec. In contrast, observations of the nearby universe consistently yield higher values, around 72 to 76 km/s/Mpc, with an average of 73 km/s/Mpc.

This discrepancy of approximately 5–6 km/s/Mpc is too significant to be attributed to methodological errors. According to researchers, it might indicate gaps in our understanding of the universe’s physics, particularly concerning the influence of mysterious components like dark energy and dark matter, which make up 96% of the cosmos’s content.

Universe expansion
Three views of NGC 4258, also known as Messier 106, which is about 23 million light-years away in the constellation Canes Venatici. The first two images show it in visible light as seen by The Kitt Peak National Observatory and the Hubble Space Telescope. The image on the right is from the James Webb Space Telescope in the infrared. Credit: ESA/WEBB, NASA & CSA, J. Glenn, KPNO/NOIRLAB/NSF/AURA / The Hubble Heritage Team (STSCI/AURA)

Some scientists propose that the conflict between measurements could stem from still-unknown properties of dark matter, exotic particles, or even modifications to existing physical laws. Another theory suggests the existence of a form of “early dark energy” that could have accelerated the universe’s expansion shortly after the Big Bang.

Marc Kamionkowski, a cosmologist at Johns Hopkins University, explains that resolving this tension could open doors to more advanced physics. Perhaps we’re overlooking a key ingredient in the early universe’s evolution. This puzzle provides theorists with vast opportunities for creativity, he says.

Although the Hubble constant does not directly affect our daily lives, its importance lies in describing how the universe evolves on a large scale. It is a fundamental pillar for mapping cosmic structure, understanding the expansion of space, and calculating critical events in the universe’s history, such as the time elapsed since the Big Bang.

The recent observations by the JWST, along with its capability to observe the universe in high definition, mark a milestone in cosmological research. As more data is gathered, scientists hope to clarify whether the Hubble tension reveals a flaw in current models or points to a completely new phenomenon in the cosmos.

SOURCES

Johns Hopkins University

Adam G. Riess, Dan Scolnic, et al., JWST Validates HST Distance Measurements: Selection of Supernova Subsample Explains Differences in JWST Estimates of Local H0. ApJ 977 120. DOI 10.3847/1538-4357/ad8c21

  • Share on:

Discover more from LBV Magazine English Edition

Subscribe to get the latest posts sent to your email.

Something went wrong. Please refresh the page and/or try again.

Follow LBV Magazine on Google News