Cosmic
Microwave Background
Radiation
13.7 billion
years ago an enormous exlposion started the begining of the
Universe. The Big Bang
started in motion what some say can ever be reversed, and that is the
Universe, as we know of it today. For thousands of years a
"primeval atom", which contained everything that we know of inside of
it, was the only that to occupy the Universe. During that
period all of the baryonic
material was
compressed so tightly that sound waves that propagated through this
mass were able to travel at the same speed as light or
electromagnetic radiation.
370,000 years after the Big Bang
there was an instant of decoupling
of electromagnetic radiation from the baryonic
material. The
baryonic substance would thus have been able to slow down and during
recombination
begin to create the basic material for the structure of
electrons,
protons, and neutrons. At the same instant of decoupling
the
electromagnetic radiation would have been able to travel throughout
the Universe, "If we'd been around
to see it, we'd have been
blinded by
a yellow-white brilliance bombarding us from all directions at
once." (Lemonick Pg. 9).
The Cosmic
Microwave Background Radiation was detected far before it was
theorized. During the late 1930's a gentlemen, S.W. Adams, was
making precise measurements of the spectra of individual stars and
noted the star Rho Ophiuchi. A certain wavelength of Rho
Ophiuchi's
spectrum was being absorbed by surrounding interstellar cyanogen
gas and Adams noticed that some of the gas was in a certain swirling
motion,
which only happens when fluids
are being
heated. Adams collaborated with another gentlemen, Andrew Keller,
and the two of them compared as many spinning molecules to non-spinning
molecules as possible and determined that the Universe was being
showered by this "stuff" with a temperature that they determined to be
equivalent t o
2.3 K (0ºC = 273K).
The first
theoretical predictions came from another pair of physicists by the
names of Ralph Alpher and Robert Herman, but their predictions came as
a byproduct of determining whether a certain theory about cosmic
evolution was true or not. George Gamow was thinking that
if the Universe were expanding, then if one were to go back a long time
ago then everything in the Universe would be extremely dense and
extremely hot and he thought that at certain temperatures certain
types of elements
would be created. Alpher was order by his Professor (Gamow) to
determine if his prediction was right so he collaborated with Herman
and they concluded that Gamow's predictions would work for the very
simpleist elements but does not stand hold for any of the heavier
ones. The team of two determined that once the primeval atom
cooled to about 6000 K there would be a decoupling of
electromagnetic radiation and baryonic material. With nothing
in the electromagnetic radiations way it would have the ability to
shine freely throughout the Universe and that light would still be
shinning today. They calculated that the electromagnetic wave would
have been
stretched from a high intensity gamma ray to a length longer then
infrared radiation and estimated a
temperature of 5 K. This light that is still shinning is
what we call today the Cosmic Microwave Background Radiation (CMB) and
can be detected everywhere.
There
have been many trials to measure the
CMB but
two stand out above all of them, COBE and WMAP.
With
deep study of the CMB five major
questions have
been answered.
Glossary
Page
References