Cosmology is like an orchestra where different sections suddenly start playing out of sync. Measurements of the universe's expansion rate (the Hubble constant) from the early and late universe give different numbers. Other observations hint at a "negative" mass for neutrinos neutron stars — a physical nonsense. And data on dark energy dark energy seem to suggest it changes over time.
The authors of a new study have found a way to restore harmony without adding new instruments. They propose that the parameter describing when the universe became transparent to light (the optical depth to reionization, τ) is slightly higher — around 0.11. It's as if the conductor nudged the strings' entrance a bit, and the whole orchestra fell into place. It turns out that this value of τ simultaneously resolves all three tensions within the standard ΛCDM model expansion of the universe.
The resulting picture is surprisingly coherent. Predictions for distances in the late universe match data from the DESI spectroscopic instrument dark energy. The properties of dark energy stop "evolving" and agree with a simple cosmological constant. To test this hypothesis, new precise measurements of the cosmic microwave background polarization cosmic dust are needed — for example, with the future LiteBIRD satellite.
Neutrinos are so light and elusive that every second, trillions of these particles, emitted by the Sun, pass through your body without you noticing.