Editing Physics (section)

====Astrophysics====
{{Main|Astrophysics|Physical cosmology}}
[[File:Hubble ultra deep field high rez edit1.jpg|thumb|left|upright=1.5|The deepest visible-light image of the [[universe]], the [[Hubble Ultra-Deep Field]]. The vast majority of objects seen above are distant galaxies.]]

Astrophysics and astronomy are the application of the theories and methods of physics to the study of [[stellar structure]], [[stellar evolution]], the origin of the Solar System, and related problems of cosmology. Because astrophysics is a broad subject, astrophysicists typically apply many disciplines of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics.<ref>{{cite web |url=http://manoa.hawaii.edu/astronomy/bs-in-astrophysics/ |title=BS in Astrophysics |publisher=University of Hawaii at Manoa |access-date=14 October 2016 |archive-url=https://web.archive.org/web/20160404195943/http://manoa.hawaii.edu/astronomy/bs-in-astrophysics/ |archive-date=4 April 2016 }}</ref>

The discovery by [[Karl Jansky]] in 1931 that radio signals were emitted by celestial bodies initiated the science of [[radio astronomy]]. Most recently, the frontiers of astronomy have been expanded by space exploration. Perturbations and interference from the Earth's atmosphere make space-based observations necessary for [[infrared astronomy|infrared]], [[ultraviolet astronomy|ultraviolet]], [[gamma-ray astronomy|gamma-ray]], and [[X-ray astronomy]].

Physical cosmology is the study of the formation and evolution of the universe on its largest scales. Albert Einstein's theory of relativity plays a central role in all modern cosmological theories. In the early 20th century, [[Edwin Hubble|Hubble]]'s discovery that the universe is expanding, as shown by the [[Hubble diagram]], prompted rival explanations known as the [[steady-state model|steady state]] universe and the [[Big Bang]].

The Big Bang was confirmed by the success of [[Big Bang nucleosynthesis]] and the discovery of the [[cosmic microwave background]] in 1964. The Big Bang model rests on two theoretical pillars: Albert Einstein's general relativity and the [[cosmological principle]]. Cosmologists have recently established the [[Lambda-CDM model|ΛCDM model]] of the evolution of the universe, which includes [[cosmic inflation]], [[dark energy]], and [[dark matter]].