Big History Semester Exam: Units 1-4 Vocab

accretion

The process by which planets form as material orbiting some stars gathers together through collisions and gravitational or electrostatic attraction, eventually forming larger and larger bodies.

asteroid

Small rocky, icy, and metallic celestial bodies left over from the formation of the Solar System which can range from a few meters to several hundred kilometers in width.

circadian rhythm

The "master clock" that controls the body's coordinated timing system, telling it when to work, eat, and sleep.brain.

core (of the earth)

The dense center of the Earth, made mostly of iron, and some nickel.

crust (of the earth)

The solid outer layer of the Earth, consisting of moving plates both of the continental (lighter, made of granite) and oceanic (heavier, made of basalts) varieties.

exoplanet

A planet outside of our Solar System.

gas giants

A type of planet that is composed primarily of gases rather than rock or other solid material.

light spectrum

Electromagnetic radiation arranged in the order of its wavelength

mantle (of the earth)

The layer of the Earth between the core and the crustcs.

orbit

The path of a body's motion through space, often dictated by the gravitational pull of one or more larger bodies.

planet

A spherical ball of rock, gas, or both, that's in orbit around a star.

planetesimal

An object, at least a kilometer or so across but much smaller than a planet, that forms through accretion during the early stages of planet formation.

protoplanetary disk

A rotating disk of gas and dust grains surrounding a newly formed star or protostar.

rocky (or terrestrial) planets

A type of planet that is composed primarily of rock and other solid material.

Solar System

The Sun and the objects that orbit it; the area in space in which the Sun's gravitational pull is the dominant force.

Sun

The star at the center of our Solar System.

Archaeon eon

The second eon in Earth's history, a time from 3.8 to 2.5 million years ago, during which the first living organisms appeared.

atmosphere

The mixture of gases surrounding a planet.

convergent plate boundaries

Found where two plates move toward each other and collide.

(chemical) differentiation

A process early in the Earth's history that produced different layers within the Earth's interior, with denser metals sinking to form the Earth's core, while progressively lighter materials formed the upper layers.

divergent plate boundaries

Found where two plates move away from each other.

greenhouse

A process by which certain trace gases in the Earth's atmosphere trap heat near the Earth's surface and so keep the Earth's climate warmer than it would be otherwise.

Hadean eon

The earliest period in Earth's history (4.5 to 3.8 billion years ago), the "hellish era," when the planet's formation was still ongoing and was unsuited to life.

ozone

A molecule consisting of three oxygen atoms, in contrast to the more common form consisting of just two oxygen atoms.

Pangaea

The vast supercontinent formed more than 200 million years ago as plate movements joined the major continental plates together.

plate tectonics

The idea that the Earth's crust (together with the upper mantle) is broken up into separate plates that are in constant motion, explaining continental drift as well as the distribution of earthquakes, volcanoes, mountain ranges, and other rock structures, and many other features of the planet.

tectonic plates

The huge rigid slabs of rock that the Earth's crust (together with the upper mantle) is broken up into, which are in constant motion.

transform plate boundaries

Found where two plates grind past each other without either producing or destroying crust.

Earth

The third planet from the Sun in our Solar System, home to many complex life forms and modern human society.

geology

The scientific study of the Earth, including its composition and history.

subduction zones

An area of convergence (collision) between two tectonic plates where the heavier plate sinks downward beneath the lighter one, which rises up.

continental drift

The idea that the Earth's continents move in relation to each other, so that continents currently separated by oceans were joined together in the past.

seafloor spreading

A process in which new ocean floor is created as molten material from the Earth's mantle rises and spreads out at the boundary between two plates.

astrophysics

The study of the properties and interactions of planets, stars, galaxies, and other astronomical

objects.

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.

Big History

A unified account of the entire history of the Universe that uses evidence and ideas from many

disciplines to create a broad context for understanding humanity; a modern scientific origin story

Complexity

A quality of an object or system that has diverse components precisely arranged in connection with one another (so that new properties emerge which did not exist in the components alone).

Cosmology

The study of the Universe on its largest scales, including its origin.

emergent properties

Properties of a complex system that are not present within its parts but that emerge

only when those parts are combined.

entropy (the law of)

The natural tendency of all things to move from order to disorder. (Note: Although

often called the law of entropy, it is more accurate to refer to it as the second law of thermodynamics

Goldilocks Conditions

Specific set of conditions necessary to enable greater complexity. The reference is

to the fairy tale Goldilocks and the Three Bears, in which Goldilocks looks for the porridge, chair, and bed that

are "just right."

History

The study of past events.

Ingredients

Components that are put together to form something new and more complex

interdisciplinary approach

An approach to a subject that uses the viewpoints of many different

kinds of scholars about the same topic.

origin story

A narrative about the beginning of the Universe and humanity.

Religion

A set of beliefs and practices that concern humanity's relationship with the spiritual, the

supernatural, and reality.

Scale

Degrees of magnification, or perspective, used to measure time, space, and size.

Science

An approach to discovering knowledge about the natural world that relies on testing ideas through

observation or experiment.

scientific notation

A method of expressing very large and very small numbers to avoid using the many

zeros that would be required otherwise.

thresholds of increasing complexity

Moments in the history of the Universe when specific ingredients

under the right "Goldilocks Conditions" come together to create something new and more complex.

Universe

disciplines

fields of study in the sciences or social sciences

parallax

the apparent displacement of an object as seen from two different points that are not on a line with the object

Universe

everything that exists anywhere, including space, time, energy, and matter

Astronomy

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

Authority

A respectable or credible source

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) / 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 and structure

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

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

Hydrogen

The simplest of all chemical elements, hydrogen has one proton

Inflation

The idea that space and time (space-time) underwent an expansion at a rate much faster than the speed of light during the first 10-36 seconds after the Big Bang

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

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.

Nucleus

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

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

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."

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

First Law of Thermodynamics

— One form of the law of conservation of energy, which states that energy may change forms but cannot be created or destroyed

carbon

A chemical element of 6 proton formed in the dying of medium and large stars; it is the basis for all life on Earth

chemical element

fundamental types of atoms, each distinguished by varying numbers of protons and electrons; they are created by dying stars

chemistry

the scientific study of the composition, structure,

cluster

a group of galaxies held together by

cosmic horizon

the distance in our universe beyond which we cannot see.

density

the mass per unit of volume of a substance

fusion

combing two hydrogen atoms to form helium releases energy; this is what powers stars

galaxy

groups of stars held together by gravity; the Milky Way is an example

ion

an atom that has a different number protons than electrons, giving it an overall positive or negative charge.

iron

The heaviest element that is formed in the dying of a medium to large star. No more fusion is possible after this element is formed; the star goes out.

Milky Way Galaxy

the spiral shaped galaxy that contains our solar system

neutron star

one possible way end product of a supernova. when a star is much more massive than our sun runs out of fuel its core may may collapse to produce a ball of neutrons more dense than anything else in the universe.

periodicity

regular, recurring trends.

periodic table of elements

the generally accepted system for organizing the known chemical elements