parsec
Astronomical unit of distance: 1 parsec = 3.26 light-years = 200 000 astronomical units = 20 trillion miles = 30 trillion kilometres. Abbreviation: pc. Parsec is an acronym for "parallax ...
oxygen
Chemical element whose atoms have eight protons each in their nuclei. In the context of relativity, more concretely: cosmology, oxygen is interesting as an indicator of chemical evolution: Oxygen nuclei are not produced during Big Bang Nucleosynthesis, but ...
Olbers’ paradox
In an infinitely extended universe that does not change over time and is evenly filled with stars, the "night sky" would look as bright as the surface of the sun. The reason: The farther away a star, the weaker the light we receive from it. But: The greater ...
observer
In the context of relativity, "observer" can mean two different things. Often, observer is synonymous with reference frame or (spacetime-)coordinate system: An observer in this sense is someone who assigns coordinates to everything that happens around him. ...
numerical relativity
Subdiscipline of physics devoted to the use of computer simulations for exploring the structure and consequences of Einstein's theories, special and general relativity. Notably, the centerpiece of general relativity are Einstein's equations, which relate ...
nucleus
Extremely dense central region of an atom, consisting of protons and neutrons held together by nuclear forces. The number of protons determines what chemical element a nucleus represents. Typical diameter for atomic nuclei are in the region of a ...
nuclear physics
That branch of physics dealing with the properties of atomic nucleus. One connection to relativistic physics is the fact that nuclear physics is needed to describe the properties of matter in the early universe of the big bang models and in the ...
