Matter & Energy, THE-VAL
Matter is the material substance that constitutes the observable universe and, together with energy, forms the basis of all objective phenomena. Energy, in physics, is the capacity for doing work. It may exist in potential, kinetic, thermal, electrical, chemical, nuclear, or other various forms.
Matter & Energy Encyclopedia Articles By Title
thermal neutron, any free neutron (one that is not bound within an atomic nucleus) that has an average energy of......
thermal radiation, process by which energy, in the form of electromagnetic radiation, is emitted by a heated surface......
thermionic emission, discharge of electrons from heated materials, widely used as a source of electrons in conventional......
thermodynamic equilibrium, condition or state of a thermodynamic system, the properties of which do not change......
thermoelectricity, direct conversion of heat into electricity or electricity into heat through two related mechanisms,......
thermoluminescence, emission of light from some minerals and certain other crystalline materials. The light energy......
thermometer, instrument for measuring the temperature of a system. Temperature measurement is important to a wide......
thermonuclear reaction, fusion of two light atomic nuclei into a single heavier nucleus by a collision of the two......
thiamin, water-soluble organic compound that is necessary for carbohydrate metabolism in both plants and animals.......
thiazine, any of three organic compounds of the heterocyclic series, having molecular structures that include a......
thiazole, any of a class of organic compounds of the heterocyclic series characterized by a ring structure composed......
thin-layer chromatography, in analytical chemistry, technique for separating dissolved chemical substances by virtue......
thiophene, the simplest sulfur-containing aromatic compound, with molecular formula C4H4S, which closely resembles......
thixotropy, reversible behaviour of certain gels that liquefy when they are shaken, stirred, or otherwise disturbed......
Thomson atomic model, earliest theoretical description of the inner structure of atoms, proposed about 1900 by......
Thomson effect, the evolution or absorption of heat when electric current passes through a circuit composed of......
thoracotropic hormone, neurohormone secreted in arthropods. After being released by neurosecretory cells of the......
thorium (Th), radioactive chemical element of the actinoid series of the periodic table, atomic number 90; it is......
thorium series, set of unstable heavy nuclei comprising one of the four radioactive...
threonine, an amino acid obtainable from many proteins. One of the last amino acids to be isolated (1935), threonine......
thulium (Tm), chemical element, a rare-earth metal of the lanthanide series of the periodic table. Thulium is a......
thunderstorm, a violent short-lived weather disturbance that is almost always associated with lightning, thunder,......
thymine, organic compound of the pyrimidine family that is a constituent of deoxyribonucleic acid (DNA). DNA, along......
thyrotropin, substance produced by cells called thyrotrophs in the anterior pituitary gland. Thyrotropin binds......
thyrotropin-releasing hormone, simplest of the hypothalamic neurohormones, consisting of three amino acids in the......
thyroxine, one of the two major hormones secreted by the thyroid gland (the other is triiodothyronine). Thyroxine’s......
tidal power, any form of renewable energy in which tidal action in the oceans is converted to electric power. There......
timbre, quality of auditory sensations produced by the tone of a sound wave. The timbre of a sound depends on its......
time, a measured or measurable period, a continuum that lacks spatial dimensions. Time is of philosophical interest......
- Introduction
- Prescientific, Influence, Conceptions
- Cyclic, Philosophy, History
- Philosophy, History, Perception
- Duration, Perception, Flow
- General Relativity, Cosmology, Physics
- Quantum, Relativity, Measurement
- Philosophy, Biology, Mind
- Measurement, Perception, Relativity
- Lengths, Calendars, Cycles
- Standardization, Measurement, Perception
- Measurement, Clocks, Calendars
- Atomic, Measurement, Clocks
- Atomic, Scales, Measurement
- Radiometric, Measurement, Clocks
time dilation, in the theory of special relativity, the “slowing down” of a clock as determined by an observer......
time perception, experience or awareness of the passage of time. The human experience of change is complex. One......
time reversal, in physics, mathematical operation of replacing the expression for time with its negative in formulas......
The Manhattan Project had its origins in 1939, when U.S. scientists urged President Franklin D. Roosevelt to establish......
tin (Sn), a chemical element belonging to the carbon family, Group 14 (IVa) of the periodic table. It is a soft,......
titanium (Ti), chemical element, a silvery gray metal of Group 4 (IVb) of the periodic table. Titanium is a lightweight,......
titanium dioxide, (TiO2), a white, opaque, naturally occurring mineral existing in a number of crystalline forms,......
titration, process of chemical analysis in which the quantity of some constituent of a sample is determined by......
toluene, aromatic hydrocarbon used extensively as starting material for the manufacture of industrial chemicals.......
tone, in acoustics, sound that can be recognized by its regularity of vibration. A simple tone has only one frequency,......
torque, in physics, the tendency of a force to rotate the body to which it is applied. The torque, specified with......
Torricelli’s law, statement that the speed, v, of a liquid flowing under the force of gravity out of an opening......
total internal reflection, in physics, complete reflection of a ray of light within a medium such as water or glass......
toxin, any substance poisonous to an organism. The term is sometimes restricted to poisons spontaneously produced......
transaminase, any of a group of enzymes that catalyze the transfer of the amino group (―NH2) of an amino acid to......
transcription factor, molecule that controls the activity of a gene by determining whether the gene’s DNA (deoxyribonucleic......
transfer RNA (tRNA), small molecule in cells that carries amino acids to organelles called ribosomes, where they......
transferase, any one of a class of more than 450 enzymes that catalyze the transfer of various chemical groups......
transferrin, protein (beta1 globulin) in blood plasma that transports iron from the tissues and bloodstream to......
transition metal, any of various chemical elements that have valence electrons—i.e., electrons that can participate......
transmutation, conversion of one chemical element into another. A transmutation entails a change in the structure......
transport phenomenon, in physics, any of the phenomena involving the movement of various entities, such as mass,......
transuranium element, any of the chemical elements that lie beyond uranium in the periodic table—i.e., those with......
transverse wave, motion in which all points on a wave oscillate along paths at right angles to the direction of......
trap, in physics, any location within a solid (generally a semiconductor or an insulator) that restricts the movement......
triad, in chemistry, any of several sets of three chemically similar elements, the atomic weight of one of which......
tributyl phosphate, an organic liquid solvent used in the extraction of uranium and plutonium salts from reactor......
trichloroethane, either of two isomeric colourless, nonflammable liquids belonging to the family of halogenated......
trichloroethylene, a colourless, toxic, volatile liquid belonging to the family of organic halogen compounds, nonflammable......
triclinic system, one of the structural categories to which crystalline solids can be assigned. Crystals in this......
triglyceride, any one of an important group of naturally occurring lipids (fat-soluble components of living cells).......
trigonal system, one of the structural categories to which crystalline solids can be assigned. The trigonal system......
trinitrotoluene (TNT), a pale yellow, solid organic nitrogen compound used chiefly as an explosive, prepared by......
triple bond, in chemistry, a covalent linkage in which two atoms share three pairs of electrons, as in the nitrogen......
tristimulus system, a system for visually matching a colour under standardized conditions against the three primary......
tritium, (T, or 3H), the isotope of hydrogen with atomic weight of approximately 3. Its nucleus, consisting of......
triton, nucleus of the heaviest hydrogen isotope, tritium, or hydrogen-3. Tritons, which consist of one proton......
tryptophan, an amino acid that is nutritionally important and occurs in small amounts in proteins. It is an essential......
tsunami, catastrophic ocean wave, usually caused by a submarine earthquake, an underwater or coastal landslide,......
tumour necrosis factor (TNF), a naturally occurring protein that is produced in the human body by the phagocytic......
tungsten (W), chemical element, an exceptionally strong refractory metal of Group 6 (VIb) of the periodic table,......
tungsten carbide, an important member of the class of inorganic compounds of carbon, used alone or with 6 to 20......
tunneling, in physics, passage of minute particles through seemingly impassable force barriers. The phenomenon......
turbulence, In fluid mechanics, a flow condition (see turbulent flow) in which local speed and pressure change......
turbulent flow, type of fluid (gas or liquid) flow in which the fluid undergoes irregular fluctuations, or mixing,......
twin paradox, an apparent anomaly that arises from the treatment of time in German-born physicist Albert Einstein’s......
twinning, in crystallography, regular intergrowth of two or more crystal grains so that each grain is a reflected......
Tyndall effect, scattering of a beam of light by a medium containing small suspended particles—e.g., smoke or dust......
Tyrian purple, naturally occurring dye highly valued in antiquity. It is closely related to indigo...
tyrosine, an amino acid comprising about 1 to 6 percent by weight of the mixture obtained by hydrolysis of most......
ubiquinone, any of several members of a series of organic compounds belonging to a class called quinones. Widely......
ultrasonics, vibrations of frequencies greater than the upper limit of the audible range for humans—that is, greater......
ultraviolet radiation, that portion of the electromagnetic spectrum extending from the violet, or short-wavelength,......
uncertainty principle, statement, articulated (1927) by the German physicist Werner Heisenberg, that the position......
undertow, a strong seaward bottom current returning the water of broken waves back out to sea. There is in fact......
uniform circular motion, motion of a particle moving at a constant speed on a circle. In the Figure, the velocity......
Universal Time (UT), the mean solar time of the Greenwich meridian (0° longitude). Universal Time replaced the......
unsaturated fat, a fatty acid in which the hydrocarbon molecules have two carbons that share double or triple bond(s)......
unsaturated polyester, any of a group of thermosetting resins produced by dissolving a low-molecular-weight unsaturated......
uracil, a colourless, crystalline organic compound of the pyrimidine family that occurs as a component of ribonucleic......
uranium (U), radioactive chemical element of the actinoid series of the periodic table, atomic number 92. It is......
uranium series, set of unstable heavy nuclei constituting one of the four radioactive...
uranium-235 (U-235), radioactive isotope of the element uranium with a nucleus containing 92 protons and 143 neutrons.......
urea, the diamide of carbonic acid. Its formula is H2NCONH2. Urea has important uses as a fertilizer and feed supplement,......
urea-formaldehyde resin, any of a class of synthetic resins obtained by chemical combination of urea (a solid crystal......
urease, an enzyme that catalyzes the hydrolysis of urea, forming ammonia and carbon dioxide. Found in large quantities......
uric acid, a compound belonging to the purine group, and the chief form in which nitrogen, resulting from the breakdown......
vacancy, in crystallography, absence of an atom or molecule from a point that it would normally occupy in a crystal.......
vacuum, space in which there is no matter or in which the pressure is so low that any particles in the space do......
valence, in chemistry, the property of an element that determines the number of other atoms with which an atom......
valence electron, any of the fundamental negatively charged particles in the outermost region of atoms that enters......