Cosmology
The Big Bang, dark matter, dark energy, and the fate of the universe
Astronomy: Big Bang Nucleosynthesis
Big Bang Nucleosynthesis In physical cosmology, Big Bang nucleosynthesis (also known as primordial nucleosynthesis, and abbreviated as BBN) is a model for the production of light nuclei (including, b...
Astronomy: Cosmic Inflation
Cosmic Inflation In physical cosmology, cosmic inflation, cosmological inflation, or just inflation, is a theory of exponential expansion of space in the very early universe. This enormous expansion ...
Astronomy: Cosmic Microwave Background
Cosmic Microwave Background The cosmic microwave background (CMB, CMBR), or relic radiation, is microwave radiation that fills all space in the observable universe. With a standard optical telescope,...
Astronomy: Cosmic Strings
Cosmic Strings Cosmic strings are hypothetical 1-dimensional topological defects which may have formed during a symmetry-breaking phase transition in the early universe when the topology of the vacuu...
Astronomy: Cosmic Voids
Cosmic Voids Cosmic voids (also known as dark space) are vast spaces between filaments (the largest-scale structures in the universe), which contain very few or no galaxies. In spite of their size, m...
Astronomy: Dark Energy
Dark Energy In physical cosmology and astronomy, dark energy is a proposed form of energy that affects the universe on its largest scales. Its primary effect is to drive the accelerating expansion of...
Astronomy: Dark Matter
Dark Matter In astronomy and cosmology, dark matter is an invisible and hypothetical form of matter that does not interact with light or other electromagnetic radiation. Dark matter is implied by gra...
Astronomy: Gravitational Lensing
Gravitational Lensing A gravitational lens is matter, such as a cluster of galaxies or a point particle, that bends light from a distant source as it travels toward an observer. The amount of gravita...
Astronomy: Gravitational Waves
Gravitational Waves Gravitational waves are waves of spacetime curvature that propagate at the speed of light and are produced by the relative motion of gravitating masses. They were first predicted ...
Astronomy: Heat Death of the Universe
Heat Death of the Universe The heat death of the universe (also known as the Big Chill or the Big Freeze) is a scientific hypothesis regarding the ultimate fate of the universe which posits the unive...
Astronomy: Large-Scale Structure
Large-Scale Structure The observable universe is a spherical region of the universe consisting of all matter that can be observed from Earth; the electromagnetic radiation from these astronomical obj...
Astronomy: Olbers' Paradox
Olbers' Paradox Olbers' paradox, also known as the dark night paradox or Olbers and Cheseaux's paradox, is a historical argument in astrophysics and physical cosmology that says the darkness of the ...
Astronomy: Redshift
Redshift In physics, a redshift is an increase in the wavelength, or equivalently, a decrease in the frequency, of electromagnetic radiation (such as light). The opposite change, a decrease in wavele...
Astronomy: The Big Bang
The Big Bang The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. Various cosmological models based on the Big Bang concep...
Astronomy: The Big Crunch
The Big Crunch The Big Crunch is a hypothetical scenario for the ultimate fate of the universe, in which the expansion of the universe eventually reverses and the universe recollapses, ultimately cau...
Astronomy: The Cosmic Web
The Cosmic Web The observable universe is a spherical region of the universe consisting of all matter that can be observed from Earth; the electromagnetic radiation from these astronomical objects ha...
Astronomy: The Drake Equation
The Drake Equation The Drake equation is a probabilistic argument used to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way Galaxy. The equation was formula...
Astronomy: The Expanding Universe
The Expanding Universe The expansion of the universe is the increase in distance between gravitationally unbound parts of the observable universe with time. It is an intrinsic expansion, so it does n...
Astronomy: The Fermi Paradox
The Fermi Paradox The Fermi paradox is the discrepancy between the lack of conclusive evidence of advanced extraterrestrial life and the apparently high likelihood of its existence. In simple terms, ...
Astronomy: The Great Attractor
The Great Attractor The Great Attractor is a region of gravitational attraction in intergalactic space and the apparent central gravitational point of the Laniakea Supercluster of galaxies that inclu...
Astronomy: The Hubble Constant
The Hubble Constant Hubble's law, officially the Hubble–Lemaître law, is the observation in physical cosmology that galaxies are moving away from Earth at speeds proportional to their distance. In ot...
Astronomy: The Multiverse Theory
The Multiverse Theory The multiverse is the hypothetical set of all universes. Together, these universes are presumed to comprise everything that exists: the entirety of space, time, matter, energy, ...
Astronomy: The Observable Universe
The Observable Universe The observable universe is a spherical region of the universe consisting of all matter that can be observed from Earth; the electromagnetic radiation from these astronomical o...