Physics is the branch of science that deals with the laws and workings of the physical universe, from the macro-scale to the quantum, subquantum, and sub-planck levels.
Physics as a fundamental science has expanded and changed tremendously since the golden age of the 20th century. Especially three major paradigm shifts have occurred: information physics, topological physics, and torsion theory.
Physics is closely tied with mathematics, and involves the study of the fundamental laws of nature, including the properties of energy, matter and their interactions. Areas of specialization include classical mechanics, thermodynamics and entropics, classical relativity, classical and transapient theories of quantum mechanics, singularity physics, hyperdimensional physics, unified field theory, superstring, supersymmetry, and brane theory, gauge theory, gravitation and supergravitation, high energy physics, interpreting transapient teachings on physics, the physics of nano-scale objects, particle physics, solid-state physics, electromagnetism, acoustics, fluids, plasmas, spectroscopy, optics and photonics, cryogenics, superconductivity, condensates, super-dense matter, to name just a few.
Physics has applications in many other fields of science and technology, including chemistry, biology, astronomy, geology, nano-scale, microscale, macro-scale, and megascale engineering, astrogation and space travel, and more.
- Acceleration - Text by M. Alan Kazlev
The rate of change of velocity. An object moving at a constant velocity in a coordinate system (reference frame) has zero acceleration. An object whose velocity is increasing has a positive acceleration; an object whose velocity is decreasing has a negative acceleration. Acceleration relative to a freely falling reference frame is experienced as gravity.
- Amat (antimatter) - Text by M. Alan Kazlev
Matter that is composed of the counterparts of ordinary matter.
- Antiproton - Text by Stephen Inniss
The antiparticle of the proton; it has all of the same properties as a proton except for its electric charge and magnetic moment, which are opposite.
- Atom - Text by M. Alan Kazlev
The smallest particle of an element that retains the chemical properties of an element.
- Baryon - Text by M. Alan Kazlev
Subatomic particles such as protons, neutrons and mesons, that are composed of quarks and subject to the strong nuclear force. Compare with leptons.
- Biophysics - Text by M. Alan Kazlev
The study of biological structures and processes using the analytical methods of physics.
- Black Body - Text by M. Alan Kazlev
An idealized body that is a perfect radiator and perfect absorber of electromagnetic radiation. A black body not only absorbs all wavelengths of energy and radiates at all wavelengths, but it does this at the maximum possible intensity for any given temperature. Black bodies do not have to be black. A star is a good approximation to a black body since stellar gases are very good absorbers of energy. Black body radiation is radiation emitted by a black body.
- Blue Shift - Text by M. Alan Kazlev
A decrease in the wavelength of the light that is emitted from an object that is moving toward the observer. This makes the object appear to be bluer than it actually is. Both red shift and blue shift are part of the Doppler Effect.
- Bose-Einstein Condensate (BEC) - Text by M. Alan Kazlev
State of matter in which a large number of bosons occupy the same quantum state. All are defined by a single quantum wave function. Has many useful properties and functions including bosers, superconductivity, micro blackholes, and exotic fluid dynamics.
- Boson - Text by M. Alan Kazlev
One of two quantum classes of fundamental particles. Distinguished by integer or zero spins (the statistics of their behaviour in groups governed by Bose-Einstein statistics, as first described by S. N. Bose and Albert Einstein) and hence being able to occupy the same quantum state at the same time. Include photons, gluons, and the Z and W weakons, plus particles such as mesons, atomic nuclei, and atoms, in which the half-integer spins of the components cancel or add to integer spins. Contrast with the fermion.
- Brown Noise - Text by M. Alan Kazlev
The sonic equivalent to Brownian Motion; a form of randomness that is the result of cumulatively adding white noise, to yield a random walk pattern. This is useful in formation of self-evolving subsentient and sentient soundscapes.
- Brownian Motion - Text by M. Alan Kazlev
The random movement of small particles suspended in liquid or gas. The motion is caused by unbalanced impacts of molecules on the particle. Some nanites use brownian motion as a power source.
- Bulk, The - Text by M. Alan Kazlev
The higher-dimension space within which the brane which defines our universe is imbedded. The highest Archailects are believed to be able to extend their processing substrates into the bulk, perhaps through the creation of basement universes connected to our own.
- C-Boundary - Text by M. Alan Kazlev
The set of points which are not the pasts of any points or the future of any point in spacetime (essentially the "edges" of spacetime).
- Carbon-Nitrogen-Oxygen (CNO) Cycle - Text by M. Alan Kazlev
Series of nuclear reactions that uses Carbon-12 as a catalyst, an ingredient which is necessary for the reaction but is not consumed. In stars more massive than Sol (>1.3 Solar masses), this cycle is the primary process that converts hydrogen into helium.
- Casimir effect, casimir field - Text by Anders Sandberg
A small attractive force which acts between two close parallel uncharged conducting plates. It is due to quantum vacuum fluctuations of the electromagnetic field which creates a lower energy density of the vacuum between the plates than outside them.
- Catalyst - Text by M. Alan Kazlev
An agent that can produce change in its surrounding environment without undergoing any change in itself. May be an element (e.g. carbon in carbon burning of very hot stars), a chemical compound, an enzyme, a bionanite, or a meme.
- Chandrasekhar Limit - Text by M. Alan Kazlev
A mass of about 1.4 Sol, the maximum for white dwarfs. A white dwarf of greater mass has too great a central pressure and cannot support itself, causing collapse into a denser object like a neutron star or black hole.
- Chaos (physics) - Text by M. Alan Kazlev
Irregular motion of a dynamic system that is impossible to predict in the long term. The subject of chaos theory and a defining quality of most complex (whether living or non-living) systems.
- Chronology Protection - Text by Anders Sandberg
The universe forbids time machines, as demonstrated by the chronology protection theorems of Lang, Picard and Joel-5.
- Closed Timelike Curve - Text by Anders Sandberg
A closed path through spacetime that is timelike. A CTC would correspond to a possible way of time travel or time communication.
- Colour Charge - Text by Anders Sandberg
The charge of the strong nuclear force. While electromagnetic charge can be positive or negative, the nuclear force charge can take three values: "red", "green" and "blue"
- Coriolis Force - Text by M. Alan Kazlev
Not a true force, but an side-effect of the rotation of a body.
- Cosmos - Text by M. Alan Kazlev
The universe, the totality of physical creation; generally including not only the observable universe but also that which is beyond the light-cone (although for some cosmos only means the visible cosmos). In some memeticities the cosmos also includes non-physical or supraphysical realities; while others refer to a series of cosmoses. There is also disagreement among philosophers, eschatologists and others over whether the cosmos had a beginning and whether it will have an end.
- CTC Wormhole - Text by Anders Sandberg
A wormhole that forms part of a loop of wormholes enabling a closed timelike curve (CTC). Such wormholes lose stability and cease to function. For this reason wormhole networks must be arranged with care.
- Decibel - Text by M. Alan Kazlev
(abbreviated dB) logarithmic scale of units for measuring the relative intensity (loudness) of sounds. 0 dB is the faintest audible sound. Even brief exposure to 120 dB is painfully loud, and damaging to the baseline human ear.
- Degenerate Gas - Text by M. Alan Kazlev
Super-compressed and very dense fluid. The molecules are virtually touching one another and the gas acts much like a solid. Unlike gases under normal conditions, the temperature in a degenerate gas does not depend on the pressure. These gases follow quantum mechanical laws.
- Degenerate Matter - Text by M. Alan Kazlev
Matter in a very high-density state in which the electrons have been squeezed from the atoms and pressure is a function of density but not temperature.
- Delta V - Text by Richard Baker
Δv (pronounced "Delta-vee") is the maximum change in the velocity of a vessel in space. The Δv in turn determines the manoeuvres that can be carried out by the ship.
- Deuterium - Text by M. Alan Kazlev
Stable isotope of hydrogen with mass (nucleon) number of 2. The nucleus contains one proton and one neutron. Deuterium is widely used in fusion reactors and for fusion-based interplanetary ships. Though more difficult to fuse, it is much more stable and widely available than tritium.
- Doppler Shift - Text by M. Alan Kazlev
Increase or decrease in wavelength as the object emitting the wave moves relative to the observer. For example, a vehicle turbine whine seems to be higher in pitch when the vehicle is approaching the observer (because the waves are compressed, shortening the wavelength), and lower in pitch when it is travelling away (the waves are elongated, lengthening the wavelength). With light waves when the light source is coming or going relative to the observer the same thing happens. For example, when a ship is moving away from a star, the star's light appears redder, as the light waves are red shifted, meaning the wavelength is longer. When a ship is moving towards a star, the light appears bluer, as the light waves are blue shifted or compressed and shortened.
- Einstein, Albert - Text by M. Alan Kazlev
Old Earth late Industrial Age German/American physicist, 90-14 BT (1879-1955 c.e.) and popular su genome template. Formulated the Theories of Special and General Relativity. Einstein won the Nobel Prize in 48 BT (1921 c.e.) for explaining the photoelectric effect.
- Electromagnetic Radiation - Text by M. Alan Kazlev
Electromagnetic radiation is so named due to the fact that the electric and magnetic properties of the wave propagate at right angles to one another in a sinusoidal manner at the speed of light.
- Electron - Text by M. Alan Kazlev
An elementary particle with a unit electrical charge and a mass 1/1837 of the proton. Electrons surround the atom's positively charged nucleus and determine the atom's chemical properties.
- Electron Capture Decay - Text by M. Alan Kazlev
Nuclear decay by capture of an atomic electron. If the decay energy is greater than 1022 keV, positron emission can also occur in competition with electron capture.
- Electron Degeneracy Pressure - Text by Chris Clowes
Highly active "degenerate motion" resulting from electrons being confined in a very small space, such as a plasma under very high pressure, and thus pushing against adjacent electrons. Being determined by the quantum mechanics, this continues even when the matter is at absolute zero.
- Energy - Text by M. Alan Kazlev
The capacity for doing work. Energy can change from one form (heat, chemical, nuclear, potential energy) to another but is always conserved. In amat, magmatter catalyzed, and nuclear reactions, mass can be converted into energy.
- Entropy (physics) - Text by M. Alan Kazlev
A measure of a system's degree of randomness or disorder; a measure of the capacity of a system to undergo spontaneous change; the transition from a more complex and unstable to a less complex and more stable state.
- Erg - Text by Timothy Weaver
Minute measure of energy. An erg is one gram*(centimeter/second)2. To put that in perspective, it takes one million ergs to make a joule of energy at it takes 4,184 joules to heat one kilogram of water at 1 degree C at 25 C (because the specific heat changes with temperature of a substance). The baseline human body heat output is 10 million joules or 10 trillion ergs in one day. So power output is an average of 115 watts. More when doing daily activities and less when inactive or asleep.
- Exotic Atoms - Text by Stephen Inniss
A term used for matter that is not composed of the usual protons, neutrons and electrons but that forms analogous structures. The constituent particles of monopolium/magmatter are an example. Some such "atoms" may be said to form "molecules" or analogues of metals or ionic compounds and may be used in the construction of such things as Banks Orbitals.
- Exotic Energy - Text by Steve Bowers
The common term for averaged null energy condition (ANEC)-violating negative energy, also sometimes known as phantom energy.
- Exotic Matter - Text by Stephen Inniss
In popular usage any highly unusual "unnatural" matter that is not composed of protons, neutrons, and electrons. This includes such substances as quarkonium, magmatter, harmonium, pentaquarks and Q-balls.
- Femtometer - Text by M. Alan Kazlev
One millionth of a billionth of a meter, the scale of quarks in nucleons, i.e. protons, neutrons, in the nucleus of the atom.
- Fermion - Text by M. Alan Kazlev
Subatomic particle with half integer spin. The Pauli Exclusion Principle prevents more than one fermion occupying a particular quantum state. This means matter is conserved during particle interactions (i.e. that the net amount of fermions is a constant). The electron is considered a typical fermion, and it is because of its half-spin quality that electrons form into "shells" providing the outer valence electrons that make chemistry work, as well as making life and atoms as we know them possible. Contrast with the boson. [after physicist Enrico Fermi]
- Feynman Diagram - Text by M. Alan Kazlev
Stylized subatomic particle interaction diagram; a basic computational tool used by baseline/sapient particle physicists in quantum field theory.
- Fixed Point - Text by M. Alan Kazlev
A point in a dynamical system's state space that maps back to itself. A stable point in which the system does not undergo a perturbation.
- Foucault Pendulum - Text by M. Alan Kazlev
A simple pendulum that tracks the rotation of a planet (or moon or orbital). As the pendulum swings, the planet rotates under the pendulum, so the pendulum seems to rotate. It was first demonstrated by Jean Bernard Foucault, in 109 BT (1851 AD) at the Paris World's Fair, Europe, Old Earth.
- Free Fall - Text by M. Alan Kazlev
A state that occurs while in orbit around a planet or other body. During free fall, the orbiting object falls toward the planet the exact same amount as the planet's surface curves beneath the object; the object seems to be continually falling toward the planet but never reaches it. The result is a condition of weightlessness.
- FTL - Text by M. Alan Kazlev
Despite remaining a dream of mindkind since time immemorial, faster than light travel (warp drive, hyperspace, etc) remains as elusive now as it ever was. The oft-repeated assertion among some FTL proponents that traversable wormholes provide a form of FTL is incorrect. Wormholes do not constitute real FTL, but rather a local curvature in space-time, allowing an object to move between two distant points at normal (slower than light) velocity.
- Gamma - Text by Mike Parisi
Term that describes the strength of relativistic effects as an object attains a significant percentage the speed of light.
- Gamma rays, γ-rays - Text by M. Alan Kazlev
Gamma radiation. A very high energy form of electromagnetic radiation, typically with wavelengths of less than 3 pm. Gamma rays are produced by specific nuclear decay processes, and are used to sterilize food and remove goo.
- General Relativity - Text by M. Alan Kazlev
A development by Einstein of his Special Relativity that includes acceleration and gravity, both of which are explained via the curvature of space-time.
- Gravitational Collapse - Text by M. Alan Kazlev
The contraction of an object like a star or an interstellar dust-cloud under its own gravitational attraction.
- Gravitational Constant - Text by M. Alan Kazlev
The constant, abbreviated 'G', of proportionality discovered by Newton that describes the gravitational attraction between objects; their gravitational attraction (F) depends only on their masses and the distance between them, according to the formula F = Gm1m2 / r2. Henry Cavendish, in 171 BT (1798 AD), determined the numerical value of G to be 6.668 x 10-8 dynes cm2/g2.
- Gravity - Text by M. Alan Kazlev
One of the fundamental physical forces of nature, it binds objects together on the macroscopic scale. Mass produces a gravitational force, which attracts all other masses. The more massive an object, the stronger the gravitational force. The late Industrial/early Atomic Age physicist Einstein showed in his theory of general relativity that gravity can be explained in terms of local curvature of space-time.
- Hadron - Text by Anders Sandberg
Matter particle consisting of quarks or antiquarks. Hadrons are divided into mesons, composed of a quark and an antiquark, and baryons, composed of three quarks or three antiquarks.
- Half-life - Text by M. Alan Kazlev
In radioactive decay, the time for half the atoms in a sample to decay to a stable state (e.g. uranium into lead). Also in general, the time in any process during which the main variable changes by half its original value.
- Inertia - Text by M. Alan Kazlev
A property of matter that resists change in motion. A mass at rest remains at rest and a mass in motion remains in motion as long as no outside force acts upon it.
- Infrared - Text by M. Alan Kazlev
Electromagnetic radiation of wavelength too long to be seen by non-tweaked hu, usually about 1 to 100 µm; usually transfers energy as heat.
- Ion - Text by M. Alan Kazlev
An electrically charged particle - either an atom or molecule that is missing one or more electrons (negative ion), or an atom or molecule that has one or more extra electrons (positive ion).
- Ionization - Text by M. Alan Kazlev
The process of knocking one or more electrons off a neutral atom or molecule, thus giving it an electrical charge. Occurs naturally in the interplanetary and interstellar medium, and also is applied in ion drive propulsion and in particle beam weapons.
- Ionized Gas - Text by M. Alan Kazlev
A gas in which many of the atoms have lost at least one electron, thus becoming ions.
- Lepton - Text by M. Alan Kazlev
Subatomic particle that is susceptible to the weak nuclear force but not the strong force (the force that binds an atomic nucleus together). There are six leptons: the electron, muon, tau, electron neutrino, muon neutrino, and tau neutrino.
- Light, Speed of - Text by M. Alan Kazlev
Designated as c, the speed of light is about 300,000 km/s and is constant as perceived by all observers.
- Light-cone - Text by Stephen Inniss
The path that light created at a single point in space and time and travelling in all directions would take through spacetime. The concept of a light cone is important to an understanding of causality.
- Lightlike - Text by M. Alan Kazlev
A path through space-time that always moves at the speed of light.
- Lyaponov Tubes - Text by Bill Glover
Lyaponov Tubes (popularly called "Transfer Manifolds" after Poincare' or "The Ell") are particularly low energy courses used to navigate between massive bodies such as planets, moons or megastructures.
- Maxwell's Demon - Text by Jonathan Burns
Old Earth Industrial Age "thought experiment". This involves two boxes of air (or similar), a tiny doorway between them, and an imaginary gadget (the demon) which opens and closes the door. The idea was that the demon could pump heat from the cool box to the hot box, if, whenever it saw a fast molecule coming from the cool side, it opened the door to let it through, then shut it again. This was intended to disprove the Second Law of Thermodynamics. It failed, because for the demon to see the molecules coming and do its agile work, it needed energy; more energy than you could get by running a heat engine from the hot box to the cold. Hence a perpetual motion machine would not work.
- Meson - Text by M. Alan Kazlev
Particles composed of a quark and an antiquark; the lowest mass mesons (the pi and K mesons) have masses intermediate between leptons and baryons. All mesons are unstable.
- Microgravity - Text by M. Alan Kazlev
A state in which gravity is reduced to virtually negligible levels. For example, when an object is in free fall, it experiences microgravity. It is deleterious to baseline physiology, but space-adapted tweaks can survive a microgravity environment indefinitely.
- Microwaves - Text by M. Alan Kazlev
Electromagnetic radiation that has a wavelength between 1 mm and 30 cm. It is widely used for energy transmission, heat generation and passive ship propulsion (maser-powered sails).
- Monopoles - Text by Adam Getchell
Elementary particles that carry units of magnetic charge. Artificial monopoles have a great many uses.
- Neutrino - Text by M. Alan Kazlev; additions by Adam Getchell
An electrically neutral lepton of spin 1/2 and extremely low mass that interacts only via the weak force and gravity and as a consequence can typically pass unimpeded through ordinary matter. A common popular illustration of this is that a burst of neutrinos could pass through a light year's thickness of lead and still retain better than two thirds of its strength. There are three known varieties in conventional matter, one in each generation of particles, associated with electron, muon, and tau leptons.
- Neutron - Text by M. Alan Kazlev
Uncharged atomic nuclear particle. It has a mass slightly greater than a proton. In beta decay, a neutron decays into a proton, an electron, and an anti-neutrino.
- Neutronium - Text by M. Alan Kazlev; additions by Adam Getchell
A transparent, superfluid and super-dense state of matter, in between electron degenerate matter and quark degenerate matter. It is composed entirely of neutrons. Neutronium occurs naturally in neutron stars, where the gravitational pressure is sufficient to force such a state and is unstable at lesser pressures.
- Newton, Isaac - Text by M. Alan Kazlev
Old Earth English mathematician and physicist (327-242 BT; 1642-1727 AD) who invented calculus (simultaneously, but independently of Leibniz), formulated the laws of gravitation, investigated the nature of light (he discovered that sunlight is made of light of different colors), and the laws of motion.
- Nuclear Fission - Text by M. Alan Kazlev
The process whereby the nucleus of an unstable (radioactive) heavy element spontaneously splits into two smaller nuclei, releasing energy and charged particles.
- Nuclear Fusion - Text by M. Alan Kazlev
Atomic reaction in which smaller nuclei fuse together to form larger ones, releasing energy in the process. Because the resultant nucleus is smaller in mass than the sum of the ones that made it; the difference in mass is converted into energy by the equation E=mc2.
- Nuclear Physics - Text by M. Alan Kazlev
The study of the physical processes at the scale of the atomic nucleus. Concerns itself with the structure and behavior of the atomic nucleus according quantum mechanics and particle physics; with practical applications in the working of nuclear reactors, radioactive fission, and fusion burning in the interior of stars.
- Nuclear Reaction - Text by M. Alan Kazlev
A self-perpetuating chain reaction involving the production of heavy nuclei from the fusion of lighter ones, or lighter nuclei from the fission of heavier ones.
- Nucleon - Text by M. Alan Kazlev
Generic term for the particles that compose the atomic nucleus: protons and neutrons in the case of ordinary matter, or antiprotons and antineutrons in antimatter.
- Nucleosynthesis - Text by M. Alan Kazlev
The production of new elements that occurs naturally in stars via nuclear reactions, and in supernova explosions. Nucleosynthesis is also an important part of alchemics.
- Nucleosynthetic Era - Text by M. Alan Kazlev
The era following the Leptonic Era, between 1 second and 1,000 seconds after the Big Bang, in which light elements (helium and deuterium) are synthesized during the hot early phases of the hot Big Bang.
- Nucleus, Atomic - Text by M. Alan Kazlev
The central part of an atom, made up of protons and neutrons, and containing nearly all of the atomic mass.
- Null Line - Text by M. Alan Kazlev
The path of a light ray or other massless object across space-time. Space-time distances measured along a null line are zero.
- Parabola - Text by M. Alan Kazlev; amended by Stephen Inniss
A conic section, a curve that is a set of points (P) such that the distance from a line (the directrix) to P is equal to the distance from P to focus F. A parabolic mirror will concentrate incoming light at a single point, or send out light from a source at that point in a collimated beam. In celestial mechanics parabolas have an eccentricity of 1, and an object in a parabolic orbit will swing past and change course but will not return since it is moving at escape velocity.
- Parallax - Text by M. Alan Kazlev
Angular shift in apparent position due to an observer's motion; more specifically, a small angular shift in a star's apparent position due to a body's (e.g. a planet or habitat's) motion around its primary, or the motion of a non-relativistic, sub-relativistic, relativistic vessel or probe from point A to point B.
- Pauli Exclusion Principle - Text by M. Alan Kazlev
Principle of subatomic physics specifying that no two electrons (or fermions in general) in a very small volume have exactly the same properties of energy, motion, and so on.
- Periapsis - Text by Stephen Inniss
In orbital dynamics, the point at which two objects in an elliptical orbit around their centre of gravity are at their closest approach. The opposite of apoapsis. Derivative terms are sometimes used for particular situations, as for instance perigee for a hab or moon orbiting a planet or perihelion for a planet orbiting a star.
- Perigee - Text by M. Alan Kazlev
For an object orbiting the Earth (or, since the Interplanetary Age, for any planet), the perigee is the point in each orbit which is closest to the primary. The perigee generally varies a small amount from orbit to orbit. The closest perigee is called the proxigee. The opposite term is apogee.
- Perihelion - Text by M. Alan Kazlev
The perihelion is a planet or comet's closest approach to the star it is orbiting.
- Periodic - Text by M. Alan Kazlev
 change or motion that goes through a finite number of regions, states, or actions, returns to a previous state, and repeats the same fixed pattern indefinitely.
 a resonance, octave, or repeated series (e.g. the periodic table).
- Phase Transition - Text by M. Alan Kazlev
In physics, a change from one state of matter to another. In dynamical systems theory, a change from one mode of behaviour to another. In distributed meso- or nano-swarms, a change in the coordination and activity of the swarm. In toposophy, a change from one singularity level to another.
- Phases of Matter - Text by M. Alan Kazlev
Matter normally exists in four phases (solid, liquid, gas, and plasma) and a few other extreme phases, like critical fluids and degenerate gases, which are often used by AIs and powers for various ultratech applications.
- Photon - Text by M. Alan Kazlev
The quantum unit of electromagnetic radiation, having some properties of a wave. For each wavelength, the photon has a different energy.
- Physical Singularity - Text by M. Alan Kazlev
A point in space-time where the standard laws of physics break down; e.g. the center of a black hole.
- Physical Universe - Text by M. Alan Kazlev
The universe of physical matter and energy, determined by physical laws. Materialism states this is the only reality, while supernaturalist religion and esotericism assert that beyond the physical universe are one or more spiritual planes or dimensions.
- Pi-zero Meson - Text by Richard Baker
Meson with neutral electric charge. Pi-zero mesons can be produced by electron-positron collisions and can decay back into an electron-positron pair, but they are not a bound state of an electron and a positron. The electron and positron annihilate to form a virtual photon and that then decays into a quark and antiquark, which form the meson.
- Plasma - Text by M. Alan Kazlev
A usually high-temperature gas consisting entirely of ions, instead of neutral atoms or molecules. Because of the high temperature, the atoms strike each other hard enough to keep at least the outer electrons knocked off. At very high temperatures - e.g. the cores of stars and in fusion reactors - self-perpetuating nuclear fusion occurs.
- Plastic (physics/chemistry) - Text by M. Alan Kazlev
A material with the properties of a solid but capable of flowing under pressure. Some of the layers of the mantle of a large Terrestrial Class planet are plastic.
- Positron - Text by Stephen Inniss
The antimatter, antiparticle counterpart of the electron, with the same mass and spin but an equal and opposite charge.
- Proton - Text by M. Alan Kazlev
One of the two basic elementary particles found the atomic nucleus, the other being the neutron. It has a positive charge equal and opposite that of the electron, and a mass similar to the neutron. Protons have a mass of 1.007276 daltons, or 1.6726 = 10-27 kg.
- Proton-Proton Chain - Text by M. Alan Kazlev
A series of three thermonuclear reactions that convert hydrogen nuclei to helium nuclei, converting a tiny amount of mass into energy. The process is efficient at temperatures above 10,000,000 K. In most less massive stars, this chain is the primary source of heat and radiation. The proton-proton chain converts hydrogen into helium releasing energy in the form of particles and gamma-rays. Hydrogen is converted into helium in a chain of reactions. The first reaction takes an average of 1 billion years to occur while the others are much shorter. Generally there are so many hydrogen nuclei that the 1 billion year waiting period does not stop it from producing tremendous radiation.
- Q-Balls - Text by Adam Getchell
Q-balls are a form of shadow matter, participating only in gravitational interactions.
- Quantum - Text by M. Alan Kazlev
Term coined by Old Earth late Industrial Age scientist Max Planck to describe an individual particle of light. At the subatomic level, matter and energy occupies discrete packages, or quanta. These govern all particle interactions and physical qualities, including electric charge, spin, and so on.
- Quantum Decoherence - Text by M. Alan Kazlev
A process in which the ambiguous quantum state of a particle, such as the nuclear spin of an electron representing a qubit in a quantum computer, is resolved into an unambiguous state, whether measured or not (conscious observers are not needed).
- Quantum Entanglement - Text by Ray Kurzweil
Relationship between two physically separated particles under special circumstances.
- Quantum Levitation - Text by Todd Drashner
A small repulsive force that acts between two close parallel uncharged objects. The effect is used in nanotechnology to increase the efficiency of nanoscale devices.
- Quantum Mechanics - Text by M. Alan Kazlev
A theory, first developed during late industrial and atomic age Old Earth, that describes the interactions of subatomic particles.
- Quantumscale - Text by M. Alan Kazlev
Generic term for the size scale at which the nature and behaviour of matter and energy is determined by quantum effects.
- Quark - Text by M. Alan Kazlev
The fundamental particles of hadronic matter such as protons, neutrons and mesons. There exist six 'flavors' of quarks: up, down, strange, charm, top and bottom. They are confined to hadrons by the strong force.
- Quarkonium - Text by Anders Sandberg
Quark matter, dense matter composed of a mass of quarks rather than quarks separated into hadrons. Occurs naturally inside dense neutron stars or as strange matter.
- R-process Reactions - Text by M. Alan Kazlev
Rapid reactions, occurring naturally inside supernovae, and artificially inside large alchemic chambers, in which heavy elements are formed as atomic nuclei capture neutrons. (See also S-process Reactions).
- Radial Velocity - Text by M. Alan Kazlev
Vr ;the velocity component along the line of sight toward or away from an observer. Recession is positive radial velocity; approach is negative radial velocity.
- Radiation - Text by M. Alan Kazlev
 Any electromagnetic waves or atomic particles that transmit energy across space.
 One of three modes of heat (energy) transmission through stars or planets from warm regions to cool regions.
 Rapid evolution of a large number of morphotypes from a single ancestor.
- Radiation Pressure - Text by M. Alan Kazlev
Outward pressure on small particles exerted by electromagnetic radiation in a direction away from the light source. Important in solar sailing.
- Rayleigh Scattering - Text by M. Alan Kazlev
Scattering of light by particles smaller than the light's wavelength. This process favors scattering of blue light, which explains why the sky on many planets that possess an atmosphere is blue.
- Redshift - Text by M. Alan Kazlev
Doppler shift of spectral features toward longer wavelengths, indicating recession of the source.
- Relative Cosmic Abundance of Elements - Text by Stephen Inniss
The universe consists almost entirely of hydrogen and helium, but of the impurities created by the processes in stars made intelligent life possible, and their relative natural abundance continues to shape the evolution of biology, technology, and society.
- Relativistic - Text by M. Alan Kazlev
Of, or pertaining to, velocities or objects travelling at close to the speed of light, which experience effects such as time dilation, mass increase, and so on, as described in Special Relativity.
- Relativity - Text by M. Alan Kazlev
The postulate that the speed of light in a vacuum is constant and independent of the source or the observer, and that the mathematical forms of the laws of physics are invariant in all inertial systems.
- Roche's Limit - Text by M. Alan Kazlev
The distance from a large body or primary within which tidal forces would disrupt or disintegrate a satellite.
- Single Electron Transfer (SET) - Text by M. Alan Kazlev
Exchange of electrons, one at a time, between two electrodes. Most nanoelectronic and molectronic circuits operate with very few or even one electron at a time.
- Space-like - Text by Anders Sandberg
A path through spacetime that always has a local velocity greater than the speed of light, and hence points in the spatial direction(s) of a Minkowski diagram. Space-like paths are not possible for physical objects.
- Space-Time - Text by M. Alan Kazlev
In physics, space and time are not disparate but interrelated and in some particle diagrams even under quantum conditions interchangeable dimensions of a single reality. This is often represented in terms of a space-time diagram.
- Space-Time Diagram (simple version) - Text by M. Alan Kazlev
A simplified chart in which time is represented as the y coordinate and space as the x coordinate, with the three spatial dimensions collapsed to one dimension. It reflects the fact that events must be specified in time and space. Used for flat surface representations, or by nearbaselines and other simple beings who find it difficult visualizing more than two dimensions.
- Special Theory of Relativity - Text by M. Alan Kazlev
Theory formulated by Old Earth physicist Albert Einstein that deals with relative motions, and takes as its starting point the fact that the speed of light is a universal constant.
- Specific Impulse - Text by M. Alan Kazlev
Isp - the measure of efficiency of rocket (does not apply to reactionless drive); how much impulse (thrust multiplied by time) is produced per unit mass of propellant.
- Spectrum - Text by M. Alan Kazlev
Light from an object arranged in order of wavelength; specifically, the colors of visible light, arranged in this order.
- Sphere of Gravitational Influence - Text by M. Alan Kazlev
The region in which the gravitational influence of a body is the dominant influence on a passing small body's motions.
- Stable Transuranic Elements - Text by Ithuriel
Superheavy nuclei with proton numbers greater than 112 and half lives of at least one year.
- Strong Nuclear Force - Text by Anders Sandberg
One of the four fundamental forces. It is transmitted by the gluon, which transmits colour charge between quarks. Since the gluon is both massless and interacts with itself, the force does not fall off over distance and is very strong compared to the other forces.
- Subatomic Particle - Text by M. Alan Kazlev
Wave-Particles that go up to make atoms, or are much smaller than atoms. Common examples are protons, neutrons, electrons, and neutrinos.
- Superconductivity - Text by M. Alan Kazlev; modified from KurzweilAI
The physical phenomenon whereby some materials exhibit zero electrical resistance at low temperatures. Superconductivity allows great computational power with little or no heat dissipation (the major limiting factor in all processing operations). The synthesizing of special materials enabling cheap and reliable room temperature superconductivity during the early Interplanetary Age represented a tremendous leap forward in many fields of technology.
- Superconductors - Text by Luke Campbell
Matter in which electric current can flow without hindrance.
- Synchrotron Radiation - Text by M. Alan Kazlev
Radiation emitted when electrons move at nearly the speed of light in a magnetic field.
- Three Body Problem - Text by M. Alan Kazlev
The problem of determining the future positions and velocities of three gravitational bodies. The problem was proved unsolvable in the general case by Old Earth Industrial Age mathematician Henri Poincaré, which in turn led to the development of chaos theory. Although no analytical solutions are possible in the worst case, a numerical solution is sometimes sufficient for many tasks. A number of hyperturing mathematicians have offered varying resolutions to the Three Body Problem, although no complete solution that is comprehensible to an intelligence of less than S5 has ever been proposed.
- Thunderbolt - Text by Adam Getchell
A beam of gravitational wave singularities which destroys the universe as it goes.
- Tidal Force - Text by Stephen Inniss
A secondary effect of the force of gravity, arising from the fact that gravitational effects are not constant across the width of an object: the portions nearer the source of gravity are subject to a stronger pull, and the portions further away are subject to a weaker pull.
- Tide - Text by Stephen Inniss
The alternate rise and fall of the surface of an open body of water or other fluid on a rotating hab, moon, or planet. Measurable tides arise from the periodic gravitational tug from some body that is sufficiently large and close to produce a significant tidal force if the period of that influence is close to the natural frequency (seiche period) of the lake, sea or ocean in question.
- Timelike - Text by Anders Sandberg
A path through space-time that always has a local velocity less than the speed of light, and hence points in the same direction as time in a Minkowski diagram.
- Tunneling - Text by M. Alan Kazlev
In quantum mechanics, the ability of electrons and other subatomic particles to exist in two places at once, in particular on both sides of a barrier. Tunneling allows some of the electrons to effectively move through the barrier and accounts for the "semi" conductor properties of a transistor. Important principle in solid-state electronics.
- Ultra-violet Radiation - Text by M. Alan Kazlev
Electro-magnetic radiation beyond the blue end of the visible spectrum. Invisible to baseline hu and most terragen biota, although bees and some geneered organisms can see it. Useful for disinfecting/decontamination, causes sunburn and cellular damage.
- Universe - Text by M. Alan Kazlev
A self-contained cosmos or a part of a cosmos. Alternatively, the entirety of what naturally exists, including the galaxies and intergalactic space, all matter and energy, and space-time generally. A bounded virch environment that cannot be breached by its inhabitants may be referred to as a universe. The archailects have created so-called 'baby' or 'basement' universes for purposes of their own. Whether our own universe is part of a larger multiverse remains a subject of debate, while the question of if other universes have been contacted is a matter of rumour, occasionally fueled by statements made by one archailect or another.
- Vector (physics/math) - Text by M. Alan Kazlev
A one-dimensional array of numbers that can be used to represent a point in a multidimensional space. Commonly in 3-space a vector is viewed as a number (a magnitude) plus a direction (compare with scalar). A vector can be represented by an arrow whose length represents the magnitude and the direction represents the direction. For example, velocity is a vector; velocity tells you how fast something is traveling, and its direction.
- Velocity - Text by M. Alan Kazlev
The speed and direction that a body is moving. It has more information than speed alone. Velocity is a vector.
- Virtual Particle - Text by Anders Sandberg
Quantum field theory allows particle-antiparticle pairs to borrow energy from the vacuum to come into existence as long as they vanish again within the time set by the Heisenberg Uncertainty Principle. The result is that the vacuum is filled with virtual particles, themselves undetectable but their collective effect visible in the form of screening effects of charged particles, the Casimir Effect and Visser decay of wormholes.
- Viscosity - Text by M. Alan Kazlev
The measure of a material's resistance to flow. Viscosity is a result of the internal friction of the material's molecules. Materials with a high viscosity do not flow readily; materials with a low viscosity are more fluid. In technology, viscosity can be an important factor in the microgravity art, the function of liquid nanoborgs, the design of nanofabrication units, and more.
- Visser Effect - Text by Xaonon
Principle that dictates that no system of wormholes can be configured in such a way as to permit time travel. The ends of any single wormhole cannot be brought more closely together than the time difference between them; i.e. if one mouth is a year younger than the other, the ends can't come closer than a light-year without causing a collapse.
- Wavelength - Text by M. Alan Kazlev
The distance between different peaks and troughs of a wave. In the electromagnetic spectrum, the shorter the wavelength, the higher the energy.
- Weak Nuclear Force - Text by Anders Sandberg
One of the four fundamental forces. It can transform an up quark into a down quark (or vice versa), causing beta-decay of radioactive nuclei. It is transmitted by the vector bosons W+, W- and Z0 whose high mass causes its range and strength to be very small.
- White Noise - Text by M. Alan Kazlev
Noise that uniformly distributed in the frequency domain; randomness that is uniformly distributed; thus, a white noise process with a range of 0 to 1 would yield a random number in this range with probability equal for all possible values. Brown noise is a result of cumulatively adding white noise. Some clades and subcultures use white noise for various aesthetic or audio-sculptural purposes. In an audiosculpture for example white noise could be used to mask a soundscape when heard from a certain angle, thus creating a 3D sonic topographic.
- Wormholes - A Layman's Guide - Text by Todd Drashner and Adam Getchell
Technical details about wormholes.
Text by M. Alan Kazlev
Modified from the original by Robert J. Hall
Initially published on 19 December 2001.