acceleration: A change in the speed or direction of some object.
artifact: Some human-made object (such as a pot or brick) that can be used as one gauge of a community’s culture or history. (in statistics or experiments) Something measured or observed that is not naturally a part of some system. It was instead introduced accidentally as a result of how the measurement or study was performed.
atom: The basic unit of a chemical element. Atoms are made up of a dense nucleus that contains positively charged protons and uncharged neutrons. The nucleus is orbited by a cloud of negatively charged electrons.
atomic: Having to do with atoms, the smallest possible unit that makes up a chemical element.
cosmos: (adj. cosmic) A term that refers to the universe and everything within it.
decay: (for radioactive materials) The process whereby a radioactive isotope — which means a physically unstable form of some element — sheds energy and subatomic particles. In time, this shedding will transform the unstable element into a slightly different but stable element. For instance, uranium-238 (which is a radioactive, or unstable, isotope) decays to radium-222 (also a radioactive isotope), which decays to radon-222 (also radioactive), which decays to polonium-210 (also radioactive), which decays to lead-206 — which is stable. No further decay occurs. The rates of decay from one isotope to another can range from timeframes of less than a second to billions of years.
electric charge: The physical property responsible for electric force; it can be negative or positive.
electricity: A flow of charge, usually from the movement of negatively charged particles, called electrons.
electromagnetic: An adjective referring to light radiation, to magnetism or to both.
electromagnetic force: ( also known as electromagnetism ) One of the four fundamental forces of nature. It’s the force that causes electrically charged particles to interact. The regions over which these interactions occur are known as electromagnetic fields.
electromagnetism: The science that has to do with the physical links between electricity and magnetism. It’s also the term for the properties of an electric current that cause it to generate a magnetic field. This term can also be applied to the physical force (the electromagnetic force) that governs interactions between charged particles and which are due to their electric charge and their release or absorption of light (photons).
electron: A negatively charged particle, usually found orbiting the outer regions of an atom; also, the carrier of electricity within solids.
force: Some outside influence that can change the motion of a body, hold bodies close to one another, or produce motion or stress in a stationary body.
friction: The resistance that one surface or object encounters when moving over or through another material (such as a fluid or a gas). Friction generally causes a heating, which can damage a surface of some material as it rubs against another.
fundamental: Something that is basic or serves as the foundation for another thing or idea.
gluon: A subatomic particle believed to bind other particles together.
graviton: A hypothetical particle that many physicists suspect is the basic unit contributing to a gravitational field. It would have no mass or electric charge and move at the speed of light. In that sense, it is somewhat like the photon, the basic unit of light.
gravity: The force that attracts anything with mass, or bulk, toward any other thing with mass. The more mass that something has, the greater its gravity.
Isaac Newton: This English physicist and mathematician became most famous for describing his law of gravity. Born in 1642, he developed into a scientist with wide-ranging interests. Among some of his discoveries: that white light is made from a combination of all the colors in the rainbow, which can be split apart again using a prism; the mathematics that describe the orbital motions of things around a center of force; that the speed of sound waves can be calculated from the density of air; early elements of the mathematics now known as calculus; and an explanation for why things “fall:” the gravitational pull of one object towards another, which would be proportional to the mass of each. Newton died in 1727.
Jupiter: (in astronomy) The solar system’s largest planet, it has the shortest day length (9 hours, 55 minutes). A gas giant, its low density indicates that this planet is composed mostly of the light elements hydrogen and helium. This planet also releases more heat than it receives from the sun as gravity compresses its mass (and slowly shrinks the planet).
magnet: A material that usually contains iron and whose atoms are arranged so they attract certain metals.
magnetism: The attractive influence, or force, created by certain materials, called magnets, or by the movement of electric charges.
mass: A number that shows how much an object resists speeding up and slowing down — basically a measure of how much matter that object is made from.
matter: Something that occupies space and has mass. Anything on Earth with matter will have a property described as “weight.”
neutron: A subatomic particle carrying no electric charge that is one of the basic pieces of matter. Neutrons belong to the family of particles known as hadrons.
newton: A unit of force named for Sir Isaac Newton, a 17th century English physicist and mathematician. One newton is an amount that would give a mass of one kilogram an acceleration of one meter per second per second.
nucleus: Plural is nuclei. (in physics) The central core of an atom, containing most of its mass.
orbit: The curved path of a celestial object or spacecraft around a galaxy, star, planet or moon. One complete circuit around a celestial body.
particle: A minute amount of something.
photon: A particle representing the smallest possible amount of light or other type of electromagnetic radiation.
physics: The scientific study of the nature and properties of matter and energy. Classical physics is an explanation of the nature and properties of matter and energy that relies on descriptions such as Newton’s laws of motion. Quantum physics, a field of study that emerged later, is a more accurate way of explaining the motions and behavior of matter. A scientist who works in such areas is known as a physicist.
poles: (in physics and electrical engineering) The ends of a magnet. (in chemistry) two areas of opposite electrical charge, one positive and one negative.
proton: A subatomic particle that is one of the basic building blocks of the atoms that make up matter. Protons belong to the family of particles known as hadrons.
quarks: A family of subatomic particles that each carries a fractional electric charge. Quarks are building blocks of particles called hadrons. Quarks come in types, or “flavors,” known as: up, down, strange, charm, top and bottom.
radioactive: An adjective that describes unstable elements, such as certain forms (isotopes) of uranium and plutonium. Such elements are said to be unstable because their nucleus sheds energy that is carried away by photons and/or and often one or more subatomic particles. This emission of energy is by a process known as radioactive decay.
star: The basic building block from which galaxies are made. Stars develop when gravity compacts clouds of gas. When they become hot enough, stars will emit light and sometimes other forms of electromagnetic radiation. The sun is our closest star.
sun: The star at the center of Earth’s solar system. It is about 27,000 light-years from the center of the Milky Way galaxy. Also a term for any sunlike star.
unit: (in measurements) A unit of measurement is a standard way of expressing a physical quantity. Units of measure provide context for what numerical values represent and so convey the magnitude of physical properties. Examples include inches, kilograms, ohms, gauss, decibels, kelvins and nanoseconds.
universe: The entire cosmos: All things that exist throughout space and time. It has been expanding since its formation during an event known as the Big Bang, some 13.8 billion years ago (give or take a few hundred million years).
