physics, natural philosophy (noun)

The Earth's atmosphere is a layer of gases surrounding the planet Earth that is retained by the Earth's gravity.

In physics and chemistry, plasma is a partially ionized gas, in which a certain proportion of electrons are free rather than being bound to an atom or molecule.

Theoretical physics employs mathematical models and abstractions of physics in an attempt to explain experimental data taken of the natural world.

In physics, the space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field.

In chemistry and physics, the atomic number is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus.

Auroras, sometimes called the northern and southern lights or aurorae, are natural light displays in the sky, usually observed at night, particularly in the polar regions.

For the current in the 19th century German idealism, see Naturphilosophie.

The Standard Model of particle physics is a theory of three of the four known fundamental interactions and the elementary particles that take part in these interactions.

In crystallography, the monoclinic crystal system is one of the 7 lattice point groups.

The weak interaction is one of the four fundamental interactions of nature.

Coulomb's law, sometimes called the Coulomb law, is an equation describing the electrostatic force between electric charges.

A star flare is a giant explosion in a star's atmosphere releasing as much energy as 6 1025 Joules.

Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated.

In physics, thermodynamics is the study of the conversion of energy into work and heat and its relation to macroscopic variables such as temperature and pressure.

Murray Gell-Mann is an American physicist who received the 1969 Nobel Prize in physics for his work on the theory of elementary particles.

In thermodynamics, the internal energy of a thermodynamic system, or a body with well-defined boundaries, denoted by U, or sometimes E, is the total of the kinetic energy due to the motion of molecules and the potential energy associated with the vibrational and electric energy of atoms within molecules or crystals.

A lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam.

In physics, tension is the magnitude of the pulling force exerted by a string, cable, chain, or similar object on another object.

Solid mechanics is the branch of mechanics, physics, and mathematics that concerns the behavior of solid matter under external actions. It is part of a broader study known as continuum mechanics.

A nuclear chain reaction occurs when one nuclear reaction causes an average of one or more nuclear reactions, thus leading to a self-propagating number of these reactions.

Thomas Young was an English polymath who made notable contributions to the fields of vision, light, solid mechanics, energy, physiology, language, musical harmony and Egyptology.

Volatility in the context of chemistry, physics and thermodynamics is a measure of the tendency of a substance to vaporize.

Chemical thermodynamics is the study of the interrelation of heat and work with chemical reactions or with physical changes of state within the confines of the laws of thermodynamics.

In crystallography, the tetragonal crystal system is one of the 7 lattice point groups.

In physics, resonance is the tendency of a system to oscillate at its maximum amplitude, associated with specific frequencies known as the system's resonance frequencies. At these frequencies, even small periodic driving forces can produce large amplitude vibrations, because the system stores vibrational energy.

In optics and physics, Snell's law, is a formula used to describe the relationship between the angles of incidence and refraction, when referring to light or other waves, passing through a boundary between two different isotropic media, such as water and glass.

In thermodynamics, work is the quantity of energy transferred from one system to another without an accompanying transfer of entropy.

The term ionization energy is most commonly used to refer to the work required to remove the topmost electron in the atom or molecule when the gas atom or molecule is isolated in free space and is in its ground electronic state.

Islamic physics refers to the study of physics within Islamic science, which flourished during the Islamic Golden Age, variously dated from the 8th century to the 16th century, when experimental physics, mathematical physics and theoretical physics were studied in the Islamic world.

Lagrangian mechanics is a re-formulation of classical mechanics that combines conservation of momentum with conservation of energy.

In statistical signal processing and physics, the spectral density, power spectral density, or energy spectral density, is a positive real function of a frequency variable associated with a stationary stochastic process, or a deterministic function of time, which has dimensions of power per Hz, or energy per Hz.