Definition/Meaning  Word/Phrase 
physicist born in Germany who formulated the special theory of relativity and the general theory of relativity; Einstein also proposed that light consists of discrete quantized bundles of energy (later called photons) (18791955) 
Albert Einstein
,
Einstein

arbitrary constant in the equations of general relativity theory 
cosmological constant

English theoretical physicist who applied relativity theory to quantum mechanics and predicted the existence of antimatter and the positron (19021984) 
Dirac
,
Paul Adrien Maurice Dirac

English astronomer remembered for his popular elucidation of relativity theory (18821944) 
Eddington
,
Sir Arthur Stanley Eddington

generalization of special relativity to include gravity (based on the principle of equivalence) 
Einstein's general theory of relativity
,
general relativity
,
general relativity theory
,
general theory of relativity

physical theory of relativity based on the assumption that the speed of light in a vacuum is a constant and the assumption that the laws of physics are invariant in all inertial systems 
Einstein's special theory of relativity
,
special relativity
,
special relativity theory
,
special theory of relativity

phenomenon located at a single point in spacetime; the fundamental observational entity in relativity theory 
event

hypothetical unit in theory of relativity 
fourth dimension

(physics) the principle that a measured quantity of mass is equivalent (according to relativity theory) to a measured quantity of energy 
massenergy equivalence

celebrated experiment conducted by Albert Michelson and Edward Morley; their failure to detect any influence of the earth's motion on the velocity of light was the starting point for Einstein's theory of relativity 
MichelsonMorley experiment
