The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. The notion of an expanding universe was first scientifically originated by physicist Alexander Friedmann in 1922 with the mathematical derivation of the Friedmann equations.
Physical cosmology is a branch of cosmology concerned with the study of cosmological models. A cosmological model, or simply cosmology, provides a description of the largest-scale structures and dynamics of the universe and allows study of fundamental questions about its origin, structure, evolution, and ultimate fate. Cosmology as a science originated with the Copernican principle, which implies that celestial bodies obey identical physical laws to those on Earth, and Newtonian mechanics, which first allowed those physical laws to be understood.
In physical cosmology, cosmic inflation, cosmological inflation, or just inflation, is a theory of exponential expansion of space in the very early universe. Following the inflationary period, the universe continued to expand, but at a slower rate. The re-acceleration of this slowing expansion due to dark energy began after the universe was already over 7.7 billion years old.
The cosmic microwave background, or relic radiation, is microwave radiation that fills all space in the observable universe. With a standard optical telescope, the background space between stars and galaxies is almost completely dark. However, a sufficiently sensitive radio telescope detects a faint background glow that is almost uniform and is not associated with any star, galaxy, or other object. This glow is strongest in the microwave region of the radio spectrum. The accidental discovery of the CMB in 1965 by American radio astronomers Arno Penzias and Robert Wilson was the culmination of work initiated in the 1940s.
In astronomy, dark matter is a hypothetical form of matter that does not interact with light or other electromagnetic radiation. Dark matter is implied by gravitational effects which cannot be explained by general relativity unless more matter is present than can be observed. Such effects occur in the context of formation and evolution of galaxies, gravitational lensing, the observable universe's current structure, mass position in galactic collisions, the motion of galaxies within galaxy clusters, and cosmic microwave background anisotropies.
The universe is all of space and time and their contents. It comprises all of existence, any fundamental interaction, physical process and physical constant, and therefore all forms of matter and energy, and the structures they form, from sub-atomic particles to entire galactic filaments. Since the early 20th century, the field of cosmology establishes that space and time emerged together in the Big Bang 13.787±0.020 billion years ago and that the universe subsequently expanded. Today the universe has expanded into an age and size that is physically only part of the observable universe, currently about 93 billion light-years in diameter, while the spatial size of the entire universe is by definition unknown and theorized to be possibly infinite.
Weakly interacting massive particles (WIMPs) are hypothetical particles that are one of the proposed candidates for dark matter.
In cosmology, the cosmological constant, alternatively called Einstein's cosmological constant, is a coefficient that Albert Einstein initially added to his field equations of general relativity. He later removed it; however, much later it was revived to express the energy density of space, or vacuum energy, that arises in quantum mechanics. It is closely associated with the concept of dark energy.
The Lambda-CDM, Lambda cold dark matter, or ΛCDM model is a mathematical model of the Big Bang theory with three major components:
- a cosmological constant, denoted by lambda (Λ), associated with dark energy
- the postulated cold dark matter, denoted by CDM
- ordinary matter
Alexei Yuryevich Smirnov is a neutrino physics researcher and one of the discoverers of the MSW Effect.
A dark star is a hypothetical type of star that may have existed early in the universe before conventional stars were able to form and thrive.
Simon David Manton White, FRS, is a British-German astrophysicist. He was one of directors at the Max Planck Institute for Astrophysics before his retirement in late 2019.
The chronology of the universe describes the history and future of the universe according to Big Bang cosmology.
In physical cosmology and astronomy, dark energy is a proposed form of energy that affects the universe on the largest scales. Its primary effect is to drive the accelerating expansion of the universe. Assuming that the lambda-CDM model of cosmology is correct, dark energy dominates the universe, contributing 68% of the total energy in the present-day observable universe while dark matter and ordinary (baryonic) matter contribute 26% and 5%, respectively, and other components such as neutrinos and photons are nearly negligible. Dark energy's density is very low: 7×10−30 g/cm3, much less than the density of ordinary matter or dark matter within galaxies. However, it dominates the universe's mass–energy content because it is uniform across space.
Joanna Dunkley is a British astrophysicist and Professor of Physics at Princeton University. She works on the origin of the Universe and the Cosmic microwave background (CMB) using the Atacama Cosmology Telescope, the Simons Observatory and the Large Synoptic Survey Telescope (LSST).
Shirley Ho is an American astrophysicist and machine learning researcher, currently at the Center for Computational Astrophysics at the Flatiron Institute, and an affiliated faculty at the Center for Data Science at New York University.
Katelin Schutz is an American particle physicist known for using cosmological observations to study dark sectors, that is new particles and forces that interact weakly with the visible world. She was a NASA Einstein Fellow and Pappalardo Fellow in the MIT Department of Physics and is currently an assistant professor of physics at McGill University.
Cora Dvorkin is an Argentine physicist, who is a professor at the physics department at Harvard University. Dvorkin is a theoretical cosmologist. Her areas of research are: the nature of dark matter, neutrinos and other light relics, and the physics of the early universe. Dvorkin is the Harvard Representative at the newly NSF-funded Institute for Artificial Intelligence and Fundamental Interactions (IAIFI)'s Board. In 2022, she was voted “favorite professor” by the Harvard senior Class of 2023. She has been awarded the 2019 DOE Early Career award and has been named the "2018 Scientist of the year" by the Harvard Foundation for "Salient Contributions to Physics, Cosmology and STEM Education". She has also been awarded a Radcliffe Institute Fellowship and a Shutzer Professorship at the Radcliffe Institute. In 2018 she was awarded a Star Family Challenge prize for Promising Scientific Research, which supports high-risk, high-impact scientific research at Harvard. In 2020, Dvorkin gave a talk on machine learning applied to the search for dark matter as part of the TEDx Río de la Plata event.
Raphael Flauger is a German theoretical physicist and cosmologist.
