# Cosmic Times 2006 Glossary

acoustic

of or relating to sound

anisotropy

The property of having measurements that differ when measured in a
different direction.

astrophysicist

A person who studies the part of astronomy that deals principally with
the physics of the universe, including luminosity, density, temperature,
and the chemical composition of stars, galaxies, and the interstellar
medium.

blackbody radiation

Blackbody radiation is produced by an object which is a perfect absorber
of heat. Perfect absorbers must also be perfect radiators. For a
blackbody at a temperature T, the intensity of radiation emitted I at a
particular energy E is given by Plank\'s law:

I(E,T) = 2 E^3^\[h^2^c^2^(e^E/kT^ - 1)\]^-1^

where h is Planck\'s constant, k is Boltzmann\'s constant, and c is the
speed of light.

cosmic microwave background (CMB)

The background of radiation mostly in the frequency range 3 x 10^8^ to 3
x 10^11^ Hz discovered in space in 1965. It is believed to be the
cosmologically redshifted radiation released by the Big Bang itself.

cosmology

The astrophysical study of the history, structure, and dynamics of the
universe.

cosmological constant

A constant term (labeled Lambda) which Einstein added to his general
theory of relativity in the mistaken belief that the Universe was
neither expanding nor contracting. The cosmological constant was found
to be unnecessary once observations indicated the Universe was
expanding. Had Einstein believed what his equations were telling him, he
could have claimed the expansion of the Universe as perhaps the greatest
and most convincing prediction of general relativity; he called this the
\"greatest blunder of my life\".

cosmos

The universe as a whole

dark energy

Dark energy is a hypothesized form of energy in space that exerts a
negative pressure. This changes the gravitational effect to account for
the differences between the theoretical and observational results of
gravitational effects on visible matter.

dark matter

Name given to the mass whose existence is deduced from the analysis of
galaxy rotation curves but which until now, has escaped all detections.
There are many theories on what dark matter could be. Not one, at the
moment is convincing enough and the question is still a mystery.

dwarfed

Appearing smaller or inferior

fluctuations

Variations in the primordial universe

Integrated Sachs-Wolfe Effect

The Sachs-Wolfe effect, named after Rainer Kurt Sachs and Arthur Michael
Wolfe, is a property of the cosmic microwave background radiation (CMB),
in which photons are gravitationally redshifted, and the spectrum
appears uneven.

luminous

Emitting light

Near-infrared telescopes.

Near-infrared telescopes collect light in the region of the
electromagnetic spectrum just below visible light. Whereas, most
infrared radiation is warm, near-infrared waves are not hot at all -- in
fact, you cannot even feel them. These shorter wavelengths are the ones
used by your TV\'s remote control.

optical telescopes

A telescope that collect light in the region of the electromagnetic
spectrum that is visible light.

polarization

A special property of light; light has three properties, brightness,
color and polarization. Polarization is a condition in which the planes
of vibration of the various rays in a light beam are at least partially
aligned.

quintessence

A hypothetic form of dark energy, a scalar field that accelerated the
expansion of the universe.

remnant

Left over; a surviving trace or vestige

Standard candles

An object in the universe of known luminosity that can be used to
calculate distances.

supernova

\(a\) The death explosion of a massive star, resulting in a sharp
increase in brightness followed by a gradual fading. At peak light
output, these type of supernova explosions (called Type II supernovae)
can outshine a galaxy. The outer layers of the exploding star are
blasted out in a radioactive cloud. This expanding cloud, visible long
after the initial explosion fades from view, forms a supernova remnant
(SNR).

\(b\) The explosion of a white dwarf that has accumulated enough
material from a companion star to achieve a mass equal to the
Chandrasekhar limit. These types of supernovae (called Type Ia) have
approximately the same intrinsic brightness, and can be used to
determine distances.

Theory of General Relativity

The geometric theory of gravitation developed by Albert Einstein,
incorporating and extending the theory of special relativity to
accelerated frames of reference and introducing the principle that
gravitational and inertial forces are equivalent. The theory has
consequences for the bending of light by massive objects, the nature of
black holes, and the fabric of space and time

undulations

A wavelike motion in a medium without permanent movement of the
particles.

Wilkinson Microwave Anisotropy Probe (WMAP)

A NASA satellite designed to detect fluctuations in the cosmic microwave
background. From its initial results published in Feb 2003, astronomers
pinpointed the age of the universe, its geometry, and when the first
stars appeared.