physics

physics -
              the science of matter and energy and their interactions.


≡natural philosophy


↔phase space - (physics)
                                   an ideal space in which the coordinate dimensions represent the variables that are required to describe a system or substance; "a multidimensional phase space".


↔containment - (physics)
                                    a system designed to prevent the accidental release of radioactive material from a reactor.


↔hodoscope - (physics)
                                 scientific instrument that traces the path of a charged particle.


↔magnet - (physics)
                            a device that attracts iron and produces a magnetic field.


↔meniscus - (physics)

                                 the curved upper surface of a nonturbulent liquid in a vertical tube.


↔nuclear reactor, reactor - (physics)

                                                  any of several kinds of apparatus that maintain and control a nuclear reaction for the production of energy or artificial elements.


↔metastability -
                        the quality of a physical system that persists in its existing equilibrium when undisturbed (or only slightly disturbed) but able to pass to a more stable equilibrium when sufficiently disturbed.


↔isotropy, symmetry - (physics)
                                              the property of being isotropic; having the same value when measured in different directions.


↔wave-particle duality, duality - (physics)

                                                             the property of matter and electromagnetic radiation that is characterized by the fact that some properties can be explained best by wave theory and others by particle theory.


↔absorption factor, absorptivity - (physics)

                                                             the property of a body that determines the fraction of the incident radiation or sound flux absorbed or absorbable by the body.


↔reluctivity - (physics)              

                                the resistance of a material to the establishment of a magnetic field in it.


↔rest mass - (physics)
                               the mass of a body as measured when the body is at rest relative to an observer, an inherent property of the body.


↔relativistic mass - (physics)
                                        the mass of a body in motion relative to the observer: it is equal to the rest mass multiplied by a factor that is greater than 1 and that increases as the magnitude of the velocity increases.


↔gravitational mass - (physics)
                                             the mass of a body as measured by its gravitational attraction for other bodies.


↔inertial mass - (physics)

                                    the mass of a body as determined by the second law of motion from the acceleration of the body when it is subjected to a force that is not due to gravity.


↔mass energy - (physics)
                                    the mass of a body regarded relativistically as energy.


↔flux density, flux - (physics)
                                             the number of changes in energy flow across a given surface per unit area.


↔absorbance, optical density, photographic density, transmission density - (physics)
                 a measure of the extent to which a substance transmits light or other electromagnetic radiation.


↔quantum - (physics)

                              the smallest discrete quantity of some physical property that a system can possess (according to quantum theory).


↔attracter, attractor - (physics)
                                            a point in the ideal multidimensional phase space that is used to describe a system toward which the system tends to evolve regardless of the starting conditions of the system.


↔Bose-Einstein statistics - (physics)
                                                   statistical law obeyed by a system of particles whose wave function is not changed when two particles are interchanged (the Pauli exclusion principle does not apply).


↔Dalton's law of partial pressures, law of partial pressures, Dalton's law - (chemistry and physics)

                                  law stating that the pressure exerted by a mixture of gases equals the sum of the partial pressures of the gases in the mixture; the pressure of a gas in a mixture equals the pressure it would exert if it occupied the same volume alone at the same temperature.


↔Boltzmann distribution law, Maxwell-Boltzmann distribution law - (physics)
                                                                                                          a 
law expressing the distribution of energy among the molecules of a gas in thermal equilibrium.


↔Fermi-Dirac statistics - (physics)
                                                 law obeyed by a systems of particles whose wave function changes when two particles are interchanged (the Pauli exclusion principle applies).


↔Charles's law, Gay-Lussac's law, law of volumes - (physics)
                                                                                     the density of an ideal gas at constant pressure varies inversely with the temperature.



↔Hooke's law - (physics)
                                   the principle that (within the elastic limit) the stress applied to a solid is proportional to the strain produced.


↔Kirchhoff's laws - (physics)
                                       two laws governing electric networks in which steady currents flow: the sum of all the currents at a point is zero and the sum of the voltage gains and drops around any closed circuit is zero.


↔law of gravitation, Newton's law of gravitation - (physics)
                                                                                  the law that states any two bodies attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.


↔law of thermodynamics - (physics)
                                                    a law governing the relations between states of energy in a closed system.
   ↔mass-energy equivalence - (physics)
                                                      the principle that a measured quantity of mass is equivalent (according to relativity theory) to a measured quantity of energy.


↔Planck's law - (physics)
                                   the basis of quantum theory; the energy of electromagnetic waves is contained in indivisible quanta that have to be radiated or absorbed as a whole; the magnitude is proportional to frequency where the constant of proportionality is given by Planck's constant.


2. physics - the physical properties, phenomena, and laws of something; "he studied the physics of radiation"



≡physical science

↔natural science -
                           the sciences involved in the study of the physical world and its phenomena.


↔acoustics -
                    the study of the physical properties of sound

Chemistry

chemistry –

                    the science of matter; the branch of the natural sciences dealing with the composition of substances and their properties and reactions.

≡chemical science

↔electronegativity, negativity - (chemistry)

                                                            the tendency of an atom or radical to attract electrons in the formation of an ionic bond.

↔atomic mass, atomic weight, relative atomic mass - (chemistry)

                                                                                          the mass of an atom of a chemical element expressed in atomic mass units.

↔molecular weight, relative molecular mass - (chemistry)

                                                                                the sum of the relative atomic masses of the constituent atoms of a molecule.

↔valence, valency - (chemistry)

                                           a property of atoms or radicals; their combining power given in terms of the number of hydrogen atoms (or the equivalent).

↔pH, pH scale - (from potential of Hydrogen)

                                                                the logarithm of the reciprocal of hydrogen-ion concentration in gram atoms per liter; provides a measure on a scale from 0 to 14 of the acidity or alkalinity of a solution (where 7 is neutral and greater than 7 is more basic and less than 7 is more acidic).

↔Dalton's law of partial pressures, law of partial pressures, Dalton's law - (chemistry and physics)

                                  law stating that the pressure exerted by a mixture of gases equals the sum of the partial pressures of the gases in the mixture; the pressure of a gas in a mixture equals the pressure it would exert if it occupied the same volume alone at the same temperature.

↔distribution law - (chemistry)

                                           the total energy in an assembly of molecules is not distributed equally but is distributed around an average value according to a statistical distribution.

↔equilibrium law, law of chemical equilibrium - (chemistry)

                                                                                   the principle that (at chemical equilibrium) in a reversible reaction the ratio of the rate of the forward reaction to the rate of the reverse reaction is a constant for that reaction.

↔Henry's law - (chemistry)

                                        law formulated by the English chemist William Henry; the amount of a gas that will be absorbed by water increases as the gas pressure increases.

↔law of constant proportion, law of definite proportions - (chemistry)

                                                                                               law stating that every pure substance always contains the same elements combined in the same proportions by weight.

↔law of equivalent proportions, law of reciprocal proportions - (chemistry)

                                                                                                      law stating that the proportions in which two elements separately combine with a third element are also the proportions in which they combine together.

↔Dalton's law, law of multiple proportions - (chemistry)

                                                                               law stating that when two elements can combine to form more than one compound the amounts of one of them that combines with a fixed amount of the other will exhibit a simple multiple relation.

↔law of mass action - (chemistry)

                                                 the law that states the following principle: the rate of a chemical reaction is directly proportional to the molecular concentrations of the reacting substances.

↔Mendeleev's law, periodic law - (chemistry)

                                                               the principle that chemical properties of the elements are periodic functions of their atomic numbers .

↔natural science -

                           the sciences involved in the study of the physical world and its phenomena.

↔chemoimmunology, immunochemistry -

                                                         the field of chemistry concerned with chemical processes in immunology (such as chemical studies of antigens  and antibodies).

↔ Mendeleev's law -

                                                          the field of chemistry concerned with chemical processes in immunology (such as chemical studies of antigens and antibodies).

↔organic chemistry -

                              the chemistry of compounds containing carbon (originally defined as the chemistry of substances produced by living organisms but now extended to substances synthesized artificially).

↔inorganic chemistry -

                                 the chemistry of compounds that do not contain hydrocarbon radicals.

↔physical chemistry -

                               the branch of chemistry dealing with the physical properties of chemical substances.

↔electrochemistry -

                                branch of chemistry that deals with the chemical action of electricity and the production of electricity by chemical reactions.

↔femto chemistry - 

                           the branch of chemistry that studies elementary (often very fast) chemical reactions as they occur; the experimental methods are often based on the use of femto second laser pulses.

↔geochemistry -

                           the chemistry of the earth's crust.

↔photochemistry -

                                branch of chemistry that deals with the chemical action of light.

↔nuclear chemistry, radiochemistry -

                                                   the chemistry of radioactive substances.

↔surface chemistry -

                               the branch of chemistry that studies processes occurring at interfaces between phases (especially those between liquid and gas).

↔atomist theory, atomistic theory, atomic theory, atomism - (chemistry)

                                                                                                    any theory in which all matter is composed of tiny discrete finite indivisible indestructible particles; "the ancient Greek philosophers Democritus and Epicurus held atomic theories of the universe".

↔Arrhenius theory of dissociation, theory of dissociation, theory of electrolytic dissociation - (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.

↔Ostwald's theory of indicators, theory of indicators - (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.