Researchers from Chiba University have measured the total amount of matter in the Universe, presenting a finding that ordinary matter makes up only about one third of the universe’s total mass-energy content. The results were published in a major scientific journal, The Astrophysical Journal, and contribute a fresh perspective to the longstanding baryon budget debate in cosmology.
The team employed a well-established method that matches the observed abundance and mass of galaxy clusters per unit volume against predictions from large-scale computer simulations. This approach helps infer the overall matter density of the cosmos by comparing real measurements with model universes created in silico.
According to the analysis, roughly 31 percent of the Universe consists of matter. The remainder is attributed to dark energy, a pervasive component driving the accelerated expansion of the cosmos. This partition aligns with a growing body of work that seeks to reconcile observations of galaxy distributions, cosmic microwave background data, and other probes under a single cosmological framework.
For the first time, spectroscopy enabled an accurate distance measurement to each galaxy cluster in the survey, enhancing the reliability of the distance ladder used in the analysis. By obtaining precise redshift information, researchers could refine the three-dimensional mapping of clusters and tighten constraints on the matter density parameter that defines the cosmic matter budget.
The study notes that the matter content of the Universe is not uniform in composition. While ordinary baryonic matter, including stars, planets, gas, and dust, accounts for a significant portion of visible structures, cosmological calculations indicate that such baryonic matter represents only about 20 percent of all ordinary matter. The remaining 80 percent of baryonic matter is believed to be tied up in diffuse forms or atmospherically concealed reservoirs that are not readily detectable with conventional observational methods. Beyond baryons lies the vast, unseen realm of dark matter, expected to make up a substantial fraction of the universe’s total matter content and to interact with visible matter primarily through gravity.
These findings reframe how researchers search for the elusive dark matter component. The results reinforce the idea that there are still substantial amounts of matter to be accounted for beyond what telescopes directly observe. Ongoing and future surveys, alongside advances in simulation techniques and spectroscopic capabilities, are expected to further illuminate the distribution and nature of both baryonic and dark matter, as well as the enigmatic dark energy that dominates the cosmic energy budget.
Overall, the results provide a more nuanced picture of how matter is distributed across cosmic scales. They highlight the power of combining galaxy cluster statistics with sophisticated simulations and precise distance measurements to quantify the universe’s composition. The work represents a meaningful step forward in understanding the matter-energy balance that shapes the evolution of cosmic structures over billions of years, offering a clearer lens through which to view the interplay between visible matter, dark matter, and dark energy [Attribution: The Astrophysical Journal].