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Big History Project unit 2

Terms in this set (33)

astronomy
The branch of science that deals with the Universe and the various objects, like stars, planets, and galaxies。
atom
A small unit of matter composed of protons, electrons, and usually neutrons. Atoms are basic building blocks of the matter we see in the Universe and on Earth.
authority
A respectable or credible source; an expert.
Big Bang
A theory, first articulated in the 1920s, proposing that the Universe started out extremely hot and dense and gradually cooled off as it expanded.
Cepheid
A star that fluctuates in brightness and provides astronomers with a reference they can use to measure great distances in the Universe.
claim
An assertion that something is true.
claim testing
The use of strategies to decide whether a story or concept should or should not be trusted.
collective learning
The ability to share, preserve, and build upon ideas over time.
Cosmic Microwave Background (CMB) or Cosmic Background Radiation (CBR)
Low-energy radiation pervading the entire Universe, released about 380,000 years after the Big Bang.
cosmology
The study of the Universe on its largest scales, including its origin.
Doppler effect
The apparent stretching out or contraction of waves because of the relative movement of two bodies.
electromagnetism
One of the four fundamental forces or interactions, along with gravity, the weak nuclear force, and the strong nuclear force.
electron
A negatively charged subatomic particle that orbits the nucleus of an atom.
energy
The capacity to do work, associated with matter and radiation. Includes kinetic energy, potential energy, and chemical energy, among others.
evidence
Concrete, verifiable information that either supports or disproves a claim.
gravity
The fundamental force of attraction between any two objects that have mass.
helium
The second simplest of all chemical elements, helium has two protons and (almost always) two neutrons. Helium was produced soon after the Big Bang.
hydrogen
The simplest of all chemical elements, hydrogen has one proton. Hydrogen was the first element produced after the Big Bang and is the most common element in the Universe.
inflation
The idea that space and time underwent an expansion at a rate much faster than the speed of light .
intuition
A "gut feeling" that is not necessarily based on logic or evidence.
light-year
A measure of distance in space; the distance that light travels in a vacuum in one year. It is equal to roughly 9.5 trillion kilometers, or 5.9 trillion miles.
logic
The application of systematic reasoning to arrive at a conclusion.
matter
The physical material of the Universe, including subatomic particles, atoms, and the substances that are built out of them.
neutron
An electrically neutral subatomic particle present in the nuclei of most atoms. Unlike protons, the number of neutrons in a given element can vary, giving rise to different isotopes of an element.
nucleus (atomic)
The extremely dense and positively-charged region at the center of an atom that consists of protons and neutrons.
parallax
The change in the apparent position of an object caused by movement of the observer.
proton
A subatomic particle with a positive electric charge. The number of protons in an atom (the atomic number) determines which element it is: For example, carbon atoms always have 6 protons, while iron atoms always have 26 protons.
redshift
The phenomenon in which light waves from distant galaxies are "stretched out," which for visible light means a shift toward the red side of the spectrum. Redshift provides scientists with strong evidence that the Universe is expanding, since the expansion of space explains the stretching of the light waves.
scientific method
The process of gathering evidence to test and refine scientific theories.
space-time
The unification of space and time into a single four-dimensional continuum or "fabric." Space makes up three of the dimensions, while time makes up the fourth, and cannot be fully separated from space. .
speed of light
The speed at which light travels in a vacuum: roughly 186,000 miles per second.
telescope
An instrument used for viewing distant objects, including planets, stars, and galaxies.
thermodynamics (first law of)
One form of the law of conservation of energy, which states that energy may change forms but cannot be created or destroyed.
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