cosmic microwave background
(CMB, cosmic microwave background radiation)
(microwave radiation coming from every direction)
Cosmic microwave background (CMB) radiation
is weak microwave electromagnetic radiation detectable in all directions,
presumed to be the result of the Big Bang.
It is quite uniform
(showing just 0.04% wavelength-variation in its peak strength,
around the celestial sphere)
but the variation that exists (anisotropy) is studied
as a means of studying the early universe.
It was discovered by accident in 1964
by Arno Penzias and Robert Wilson, earning them
the 1978 Nobel Prize, having been predicted in
1948 by Ralph Alpher and Robert Herman.
The photons actually date to the time of recombination,
representing a "picture" of that time, at about redshift 1090.
At that time, the universe became transparent as the combination
of electrons and protons throughout space yielded neutral
hydrogen, which is much less likely to capture or scatter photons.
The spectrum is basically a redshifted 3000K black-body spectrum,
appearing now as a 2.725K black body spectrum. The very slight
deviations from this are very much studied to answer questions
about conditions during the formation and transmission of the radiation.
Other types of radiation (cosmic background radiation) have also been found.
(The phrase cosmic background radiation is sometimes
used to mean specifically the CMB.)
In planetary astronomy, the initials CMB are also used to
abbreviate an entirely different phrase:
core-mantle boundary, i.e., the border of a planet's core.
| || |
|1.1mm||282.2GHz||1.2meV||cosmic microwave background|
| || |
|1090||4.28Gpc||13.97Gly||cosmic microwave background|
Atacama Cosmology Telescope (ACT)
angular power spectrum
baryon acoustic oscillations (BAO)
Cosmic Anisotropy Telescope (CAT)
cosmic background radiation (CBR)
cosmic infrared background (CIB)
cosmic optical background (COB)
Cosmic Background Explorer (COBE)
extragalactic background light (EBL)
epoch of reionization (EOR)
gravitational wave background (GWB)
initial fluctuation spectrum
magnetic energy spectrum
maximum likelihood mapmaking
spectral energy distribution (SED)
South Pole Telescope (SPT)
Sachs-Wolfe effect (SWE)
Sunyaev-Zel'dovich Array (SZA)
Sunyaev-Zel'dovich effect (SZ effect)
Thomson optical depth
Very Small Array (VSA)
Wilkinson Microwave Anisotropy Probe (WMAP)