a well-substantiated explanation of some aspect of the natural world; an organized system of accepted knowledge that applies in a variety of circumstances to explain a specific set of phenomena

a particular branch of scientific knowledge

(cosmology) the theory that the universe originated sometime between 10 billion and 20 billion years ago from the cataclysmic explosion of a small volume of matter at extremely high density and temperature

(cosmology) the theory that the solar system evolved from a hot gaseous nebula

(cosmology) the theory that the solar system was formed by the gravitational accumulation of planetesimals

(cosmology) the theory that the universe maintains a constant average density with matter created to fill the void left by galaxies that are receding from each other

(physics) the theory that any two particles of matter attract one another with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them

a particular branch of scientific knowledge