Relativity

rel-uh-TIV-ih-tee /ˌrɛləˈtɪvɪti/
nounC2GRE
formalscientific

The theory of the universe developed by Albert Einstein, comprising two parts: special relativity and general relativity, which deal with the relationship between space and time, and the nature of gravity.

Special relativity deals with objects moving at constant speeds and describes the relationship between space and time. General relativity extends this to include acceleration and gravity, describing gravity as the curvature of spacetime caused by mass and energy.

The story behind the word. The word 'relativity' comes from the Latin relativus, meaning 'having reference or relation to.' This root emphasizes the core idea of Einstein's theories: that measurements of space and time are not absolute but are 'relative' to the observer's frame of reference. The term was adopted to encapsulate his revolutionary ideas that challenged the absolute notions of space and time held by Newtonian physics.

Word family

  • relative (adjective): Considered in relation or in proportion to something else.
  • relativist (noun): A proponent of relativity theory.
  • relativistic (adjective): Relating to the theory of relativity.

Collocations

  • special relativity
  • general relativity
  • theory of relativity
  • quantum relativity

Example sentences

  • "Einstein's theory of Relativity fundamentally changed our understanding of space, time, and gravity." Referring to a scientific theory.
  • "The concept of time dilation, where time passes differently for observers in relative motion, is a key prediction of special Relativity." Explaining a concept.

Memory hook

Think 'RELATIVE' measurements of time and space. Everything is relative! Relative Measurements

When not to use

Do not use 'relativity' to mean simply 'relative' or 'subjective' in a philosophical sense. It refers specifically to Einstein's scientific theories. Avoid using it casually.

Fun facts

  • One of the most famous equations, E=mc², comes from Einstein's special theory of relativity.
  • GPS systems rely on both special and general relativity to function accurately, as time runs slightly differently on satellites than on Earth.
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