Physical cosmological concepts

electromagnetic radiation as a remnant from an early stage of the universe in Big Bang cosmology

repulsive property with constant energy density theorized to make up most of the universe’s energy content to account for its observed expansion

spherical region of the Universe comprising all matter that can be observed from Earth at the present time

theory of rapid universe expansion

constant representing stress-energy density of the vacuum in Einstein's equation, which accounts for the rate of expansion of the universe

increase in distance between parts of the universe over time

time elapsed since the universe came into being

nucleosynthesis that occurred during the Big Bang (between ca. 10⁻² and 200 seconds after the Big Bang)

notion that the spatial distribution of matter in the universe is homogeneous and isotropic at large scales

group of stars sharing similar characteristics

area of study in astrophysics

physical quantity representing the energy per volume

succession of methods by which astronomers determine the distances to celestial objects

earliest period of time in the Universe where the temperature was at or above the Planck temperature

In physical cosmology, baryogenesis (also known as baryosynthesis) is the physical process that is hypothesized to have taken place during the early universe to produce baryonic asymmetry, the observation that only matter (baryons) and not antimatter (antibaryons) is detected in the universe (other than in cosmic ray collisions). Since it is assumed in cosmology that the particles we see were created using the same physics we measure today, and in particle physics experiments today matter and antimatter are always symmetric, the dominance of matter over antimatter is unexplained.

subject of cosmology

increase in the expansion rate of the universe, attributed to dark energy

The systematic spread of matter and energy across the (observable) universe

dark matter that moves slowly compared to the speed of light and interacts very weakly with ordinary matter and electromagnetic radiation

possible non-random component of the peculiar velocity of galaxy clusters

thumb|Phases of the reionization In the fields of Big Bang theory and cosmology, reionization is the process that caused electrically neutral atoms in the primordial universe to reionize after the lapse of the "dark ages". Detecting and studying the reionization process is challenging but multiple avenues have been pursued. This reionization was driven by the formation of the first stars and galaxies.

cosmological fine-tuning problem

distortion of cosmic microwave background in galaxy clusters

background energy existing in space

hypothetical vacuum, less stable than true vacuum

trend in astronomy

class of hypothetical redshift mechanisms

production of the elements in a supernova explosion

purported correlation of the cosmic microwave background with the Earth’s ecliptic

dark matter consisting of particles that travel with ultrarelativistic velocities

background particle radiation composed of neutrinos that arose when neutrinos decoupled around 1 second after the Big Bang

hypothetical form of dark energy

astronomical spectroscopic term

spherical region of the observable universe surrounding an observer beyond which objects recede from that observer at a rate greater than the speed of light due to the expansion of the Universe

non-mainstream theory in physics remaining to be validated

formation of galaxies, galaxy clusters and larger structures from small early density fluctuations

random gravitational-wave signal potentially detectable by gravitational wave experiments

empirical power-law relation between the luminosity and the central stellar velocity dispersion of elliptical galaxy