scientific theory

(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

theory that the total organization of an organism rather than the functioning of individual organs is the determinant of life processes

a theory of the structure of the atom

(biology) the theory that cells form the fundamental structural and functional units of all living organisms; proposed in 1838 by Matthias Schleiden and by Theodor Schwann

(physics) the theory that light is transmitted as waves

(physics) the theory that light is transmitted as a stream of particles

(physics) a theory that gases consist of small particles in random motion

(physics) the theory that space and time are relative concepts rather than absolute concepts

(physics) a theory that tries to link the four fundamental forces

(physics) a physical theory that certain properties occur only in discrete amounts (quanta)

(quantum theory) the theory that it is impossible to measure both energy and time (or position and momentum) completely accurately at the same time

(medicine) the theory that all contagious diseases are caused by microorganisms

(computer science) a statistical theory dealing with the limits and efficiency of information processing

(chemistry) theory that describes aqueous solutions in terms of acids (which dissociate to give hydrogen ions) and bases (which dissociate to give hydroxyl ions); the product of an acid and a base is a salt and water

(biology) a scientific theory of the origin of species of plants and animals

(chemistry) the theory that all indicators are either weak acids or weak bases in which the color of the ionized form is different from the color before dissociation

(biology) a theory of how characteristics of one generation are derived from earlier generations

(psychology) a theory that association is the basic principle of mental activity

(psychology) a theory that reduces all mental phenomena to simple elements (sensations and feelings) that form complex ideas by association

a psychology based on the assumption that all mental process are useful to an organism in adapting to the environment

(psychology) a theory of psychology that emphasizes the importance of configurational properties

(economics) a theory of competition stated in terms of gains and losses among opposing players

(physics) a theory of atomic structure that combined Rutherford's model with the quantum theory; electrons orbiting a nucleus can only be in certain stationary energy states and light is emitted when electrons jump from one energy state to another

first modern concept of atomic structure; all of the positive charge and most of the mass of the atom are contained in a compact nucleus; a number of electrons (equal to the atomic number) occupy the rest of the volume of the atom and neutralize the positive charge

a generalization of special relativity to include gravity (based on the principle of equivalence)

a 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

a theory that the temperature of a body increases when kinetic energy increases

the theory of inheritance based on Mendel's laws

a theory of organic evolution claiming that new species arise and are perpetuated by natural selection

a theory of organic evolution claiming that acquired characteristics are transmitted to offspring

a theory of evolution holding that evolutionary change in the fossil record came in fits and starts rather than in a steady process of slow change