| j | k
| x | y | z|
-- the response to a changing environment of
an organism's structure or function in a way
that improves its chance for survival and
alpha process -- the capture of
helium nuclei, thus producing a heavier
nucleus. (Physicists call helium nuclei
agriculturist -- the main job
description of our ancestors beginning some
10,000 years ago, namely those who mastered
amino acid -- an organic molecule
containing carboxyl and amino groups, of
which 20 different types form the building
blocks of all proteins comprising life on
angular momentum -- the tendency
of an object to keep spinning or moving in a
artificial intelligence -- the
study of problem solving and decision making
by machines in a way often done by humans.
assumptions of mediocrity -- the
reasoned idea that we are not alone in the
Universe; rather, given the enormity of
space and the vastness of time, life arises
in many cosmic locations.
atom period -- a time interval in
the early Universe when some elementary
particles began to cluster, thus fashioning
the first atoms.
Australopithecus -- the
designation given to those prehuman
creatures having a mixture of ape-like and
human-like qualities, and who live several
million years ago.
autotroph -- any organism that
survives on inorganic matter and an external
energy source, such as photosynthesizing
plants the world over.
axon -- the main extrusion of a
neuron which acts as a transmitter of
bang -- a popular term describing the
explosive start of the Universe.
biological evolution -- the
changes, from generation to generation,
experienced by life forms throughout the
history of life on Earth.
bipedal -- an adjective meaning
"having two feet" and/or "an
ability to walk on two legs."
black hole -- a region containing
a huge amount of mass compacted into an
extremely small volume, thus making its pull
of gravity so strong that not even light can
escape--hence its name.
chondrite -- a meteorite having embedded
pebble-sized granules which contain
significant quantities of organic
cell -- the simplest type of
clustered matter having the common
attributes of life--birth, metabolism, and
chemical evolution -- the
prebiological changes that transformed
simple atoms and molecules into the more
complex chemicals needed for the origin of
closed Universe -- a model
Universe that stops expanding at some time
in the future, after which it contracts to a
point much like that from which it began.
collision theory -- the idea, now
out of favor, that the planets formed from
hot streaming debris torn from the Sun
during a near-collision or close encounter
with another passing star.
condensation theory -- the idea,
broadly accepted today, that the planets
originated from gravitationally contracting
and chemically condensing eddies as a
natural by-product of the formation of the
consciousness -- that property of
human nature generally, or of the mind
specifically, that grants us self-awareness
and a sense of wonder.
cosmic background radiation -- a
weak, electromagnetic (mostly radio) signal
that permeates all of space, thought to be
relic radiation of the big bang.
cosmic evolution -- the sum total
of all the many varied changes in the
assembly and composition of radiation,
matter, and life throughout the history of
cosmology -- the study of the
Universe on the grandest scale, especially
its origin, evolution, and destiny.
critical universal density -- the
density of matter above which the Universe
is closed and below (or equal to) which the
Universe is open.
cultural evolution -- the changes
in the ways, means, actions and ideas of
societies, including the transmission of
same from one generation to another.
condensation -- the linking of two or
more amino acids by means of removing water.
DNA -- an acronym for
deoxyribonucleic acid, a long, helical,
self-replicating molecule resident chiefly
in biological nuclei, and mainly responsible
for transmitting hereditary information and
for the building of proteins.
dendrite -- one of a network of
extrusions of a neuron which acts as a
receiver of information.
Drake equation -- a mathematical
formula that attempts to evaluate the
prospects for technologically intelligent
life in the Milky Way Galaxy.
force -- the force that binds charges of
opposite electric charge and repels charges
of identical electric charge.
eukaryote -- a life form whose
cells have well-developed biological nuclei.
event horizon -- a region within
which no event can ever be seen, heard, or
known by anyone outside; also termed the
"surface" of a black hole.
-- a zone of weakness where crustal rocks
dislodge (as in earthquakes) or mantle rocks
upwell (as in volcanos).
fermentation -- the extraction of
energy via the capture and chemical
breakdown of small molecules.
fossil -- the hardened remains of
a dead organism whose outlines or bony
features are preserved in ancient rocks.
fragmentation -- developing
inhomogeneities in the gas density of a
cloud which eventually breaks down into
smaller clumps of matter within the cloud.
-- a colossal collection of billions of
stars and interstellar matter, held together
by gravity; the Milky Way is one such
galaxy period -- a time interval
in the relatively early history of the
Universe when the galaxies formed.
gene -- a segment of any DNA
molecule containing information for the
construction of one protein, hence
responsible for directing inheritance from
generation to generation.
gene pool -- The spread or
distribution of the variations or traits
among a given population of a species; all
the genes in a given population.
genetic code -- an encyclopedic
blueprint of the physical and chemical
properties of all of an organism's cells and
all of its functions.
genetics -- the study of genes,
especially how they operate and change.
geography -- the study of
positions, shapes, sizes, and numerous other
qualities of Earth's continents.
grand unified theory -- an idea
that three forces--the electromagnetic
force, the strong nuclear force, and the
weak force--are different manifestations of
one and the same force.
gravitational force -- the force
that holds matter together on large scales,
such as stars within galaxies, atoms within
stars, and people on Earth.
gravitational instability -- a
condition whereby an object's
(inward-pulling) gravitational potential
energy exceeds its (outward-pushing) thermal
energy, thus causing the object to infall.
zone -- a three-dimensional region of
"comfortable" temperatures that
surrounds every star.
hadron period -- a very early time
interval in the history of the Universe when
heavy, strongly interacting, elementary
particles, such as protons and neutrons,
were the most abundant type of matter.
Hayashi track -- an evolutionary
stage of a protostar about to become a
main-sequence star, and named after the
Japanese astronomer who first studied such
changes in detail.
helium flash -- the rapid onset of
helium fusion in a red giant star.
heredity -- the transmission of
genetic traits from parents to offspring,
thus ensuring the preservation of certain
characteristics among future generations of
heterotroph -- any organism
requiring organic matter for food, such as
primitive cells that survived by absorbing
acids and bases floating on primordial seas.
Homo erectus -- The species
designation given to all human creatures who
lived from roughly 0.3 to 1 million years
ago; literally, the Latin means "erect
Homo sapiens -- The species
designation given to all human creatures who
lived during approximately the past 300,000
years, including ourselves; literally, the
Latin means "wise man."
Hubble's constant -- the
proportionality factor between the distance
of a galaxy and velocity with which it
recedes; currently taken to be about 22
Hubble's law -- an empirical
finding linking the distance of a galaxy and
the velocity with which it recedes.
hunter-gatherer --the main job
description of our ancestors during most of
the past few million years, namely those who
survived by hunting and gathering food.
age -- a period of cool, dry climate
that intermittently plagues planets,
causing, in the case of Earth, a long-term
buildup of ice far from the poles.
inflation -- a period of extremely
rapid expansion of the Universe shortly
after the Universe originated.
invertebrate -- a backbone-less
contraction phase -- an early
evolutionary stage of an interstellar cloud
fragment about to become a protostar.
period -- a very early time interval in
the history of the Universe when the
lightweight, weakly interacting, elementary
particles, such as electrons and neutrinos,
were the most abundant type of matter.
linear momentum -- the tendency of
an object to keep moving in a straight line.
Era -- a period in the history of the
Universe (including now) when the density of
energy contained within matter exceeded the
density of energy contained within
multicell -- a cluster of cells
that collaborate with other cells.
mutation -- a random, microscopic
change in one or more genes of an organism,
transmissible by replication.
selection -- the process whereby those
life forms having advantageous traits are
able to adapt to a changing environment,
thereby surviving, reproducing, and passing
on to their descendants those favorable
traits which then accumulate in the
population over time.
nebular theory -- the idea that
the Solar System originated in a
contracting, swirling cloud of gas that left
behind a concentric series of rings from
which the planets formed.
neuron -- a biological, or nerve,
cell in a brain.
neutron star -- an extremely
compact ball of neutrons having the mass of
a star but a size smaller than a planet.
nova -- a star that rapidly
brightens while expelling a small fraction
of its matter, after which it slowly fades
back to normal.
nuclear transformation -- changes
in atomic nuclei owing to the reaction of
one nucleus with another nucleus.
nuclear force -- the force that
binds atomic nuclei.
nucleic acid -- a class of
long-chain, organic molecules, made by
grouping many nucleotides and often
inhabiting the biological nuclei of cells.
nucleotide base -- one of five
such molecules that comprise the building
blocks of all nucleic acids within genes
that transmit hereditary characteristics
from one generation of life to the next.
-- the study of the ocean's motion, history,
and physical and chemical behavior.
open Universe -- a model Universe
that expands forever.
oscillating Universe -- a model
Universe that continuously cycles between
expansion and contraction.
-- the study of prehistoric humanity.
paleomagnetism -- the study of
paleontology -- the study of the
fossilized remains of dead organisms.
panspermia -- a theory that
stipulates germs to be everywhere in the
Universe, and that primitive life on Earth
originated when some of those germs came to
our planet from outer space.
photodisintegration -- the
breakdown of heavy nuclei by means of
photosynthesis -- the extraction
of energy from ordinary sunlight when that
light stimulates carbon dioxide and water to
change into oxygen and carbohydrates.
planet -- a rocky and/or gaseous
body, generally much smaller and cooler than
a star; the Earth is one such planet.
planetary evolution -- the changes
in the physical and chemical properties of
planets during the course of their
planetary nebula -- a twofold
object comprising an old, yet hot
white-dwarf star surrounded by a thin,
ionized shell of expanding gas.
planetesimal -- an asteroid-sized
blob of matter that gradually collided with
others in the formative stages of the Solar
System, thus fabricating the planets.
plate tectonics -- the study of
plate movements which are thought to be
responsible for many of the major geological
features on planet Earth; popularly termed
primordial nucleosynthesis --
element building that occurred in the early
Universe when the nuclei of primordial
matter collided and fused with one another.
prokaryote -- a life form whose
single cell lacks a well-developed
protein -- a class of large,
organic molecules, made of many amino acids
and inhabiting the cytoplasm of cells.
proteinoid microsphere -- a
microscopic protein-like cluster of
molecules rich in amino acids.
protogalaxy -- a forerunner of a
present-day galaxy, also sometimes termed a
protoplanet -- a forerunner, or
progenitor, of a genuine planet.
protostar -- an embryonic
condensation of interstellar matter perched
at the dawn of star birth.
pulsar -- a compact, star-like
object that emits rapid and periodic pulses
of radiation, and which is thought to be a
punctuated equilibrium -- the idea
that life's species remain essentially
unchanged for long periods of time, after
which they change rapidly in response to
sudden, drastic changes in the environment.
-- a fractionally charged, basic building
block of protons, neutrons, and many other
Era -- a period in the early Universe
when the density of energy contained within
radiation exceeded the density of energy
contained within matter.
Ramapithecus -- the
designation given to a possible ancestor of
both the australopithecines and humans,
dating back roughly 10 million years.
r-process --element building that
occurs in highly evolved stars when a
neutron is "rapidly" captured by a
red giant star -- an old, bright
star, much larger in size and cooler than
respiration -- a chemical process
whereby cells use oxygen to release energy;
a technical term for "breathing."
method -- the investigative technique
used by all natural scientists throughout
the world; in general, some data or ideas
are first gathered, then a theory is
proposed to explain them, and finally an
experiment is devised to test the theory.
s-process -- element building that
occurs in highly evolved stars when a
neutron is "slowly" captured by a
shock wave -- a rapidly rushing
shell of gas that tends to push aside and
sometimes implode matter in its wake.
secondary atmosphere -- gases that
a planet exhales from its interior after
having lost its primary, or primordial,
singularity -- a superhot,
superdense state of matter, where the known
laws of physics are likely to break down.
Solar System -- the collection of
planets, moons, and related objects orbiting
about the Sun; the Earth is one such member
of the Solar System.
speciation -- the change of a
single species into two or more new species;
also termed "disruptive
species -- a classification of
life denoting not only individuals that are
structurally similar but also able to mate
among themselves and produce fertile
spontaneous generation -- the
theory, now out of favor, that life forms
suddenly emerged fully developed from
peculiar arrangements of non-living matter.
star -- a gaseous object so hot
that its core fuses lighter nuclei into
heavier nuclei; the Sun is one such star.
stellar period -- a time interval
in the history of the Universe (including
now) when the stars form.
stellar evolution -- the changes
experienced by stars as they originate,
mature, and terminate.
stellar nucleosynthesis -- element
building that occurs in stars when nuclei
collide and fuse with one another.
supernova -- an explosive death of
a massive star whose glowing debris produce
for a short time a great brightening.
supernova remnant -- the remains
of a supernova, namely glowing debris
scattered over a light-year or more.
synapse -- a microscopic gap
separating an axon of one neuron from a
dendrite of another neuron.
-- the disordered, irregular motion of
matter, so complex as to defy description
except in a statistical manner.
-- a single cell that does not collaborate
with other cells.
Universe -- the totality of all
space, matter, and energy.
-- an organism having a backbone, and
including fishes, amphibians, reptiles, and
virus -- the smallest and simplest
entity that sometimes appears to be alive.
hole -- the radio domain between the
21-centimeter wavelength spectral line of
hydrogen (H) and the 18-centimeter
wavelength spectral lines of the hydroxyl
weak force -- the force that
governs the change of one kind of elementary
particle into another.
white dwarf star -- an old, dim
star, much smaller in size and hotter than