The density of the universe determines its geometry and fate. Current measurements show it is composed of 5% normal matter, 27% dark matter, and 68% dark energy, with a total density very close to the critical value. This article explores the cosmic density budget, the epochs that shaped the universe, and the evidence from missions like Planck and WMAP.
The tensor-to-scalar ratio (r) measures the relative strength of primordial gravitational waves versus density fluctuations in the early universe. It is a key observable for testing cosmic inflation and is probed through the B-mode polarization of the cosmic microwave background.
Quantum gravity is the theoretical bridge between general relativity and quantum mechanics, essential for understanding the Planck epoch — the earliest phase of the universe. This interactive guide explores the full cosmic timeline from the initial singularity to the present day, covering inflation, nucleosynthesis, recombination, and structure formation.
The first galaxies formed a few hundred million years after the Big Bang, ending the cosmic dark ages. Their observational signatures include ultraviolet continuum, Lyman-alpha emission, and nebular lines like H-alpha, which JWST is now detecting.
Explore the electroweak epoch, the Higgs mechanism, and the full cosmic timeline from the Planck epoch to structure formation. This definitive guide explains how the universe evolved, how particles gained mass, and what evidence supports our current model.
The Sachs-Wolfe effect describes how gravitational redshift imprints temperature variations on the cosmic microwave background, revealing the seeds of cosmic structure. This article explains the effect, its role in cosmology, and the cosmic epochs it helps illuminate.
Cosmic variance is the inherent statistical uncertainty in cosmological observations because we can only see one universe. This article explains its origins, its impact on measurements of the cosmic microwave background, and how it shapes our understanding of the cosmos.
The deceleration parameter q measures how the expansion of the universe changes over time. A negative q today indicates cosmic acceleration, a discovery that reshaped modern cosmology.
Baryogenesis is the hypothetical process that generated the observed imbalance between matter and antimatter in the early universe. This article explains the Sakharov conditions, the leading scenarios, and how this asymmetry shaped the cosmic timeline from the Planck epoch to the formation of galaxies.
Baryon acoustic oscillations (BAOs) are a fossil imprint of sound waves in the early universe, appearing as a subtle clustering pattern in galaxy distributions. Galaxy surveys detect this pattern by measuring the correlation function or power spectrum, revealing a characteristic scale that serves as a standard ruler for cosmic expansion. This guide explains the detection method, its cosmic significance, and the full timeline of cosmic evolution from the Planck epoch to today.
