cosmic microwave background
(CMB, CMBR, CBR, MBR, cosmic microwave background radiation)
(microwave radiation coming from every direction)
Cosmic microwave background (CMB or CMBR, CBR, MBR)
is weak microwave electromagnetic radiation detectable in all directions,
presumed to be a result of the Big Bang.
It is quite uniform
(showing just 0.04% wavelength-variation in its peak strength,
throughout the celestial sphere)
but the variation that exists (CMB anisotropies) is studied
as a means of studying the early universe.
The CMB 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 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 scatter photons.
The photons reaching us now have traveled directly from a spherical
shell-shaped portion of the universe termed
the surface of last scattering.
The spectrum is basically a redshifted 3000 K black-body spectrum,
appearing now as a 2.725 K black body spectrum.
Other types of radiation from every direction (cosmic background radiation) have also been found,
though the phrase cosmic background radiation is sometimes
used to mean specifically the CMB.
The phrase CMB foreground refers to microwave emission from
nearer sources at the same frequencies. Such nearer
sources are of interest to CMB researchers so they can be accounted
for to work out an accurate picture of the CMB.
In planetary science, the initials CMB are also used to
abbreviate an entirely different phrase:
core-mantle boundary, i.e., the border of a planet's core.
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|1.1mm||282.2GHz||1.2meV||cosmic microwave background|
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|1090||4.29Gpc||13.98Gly||cosmic microwave background|
Referenced by pages:
Atacama B-Mode Search (ABS)
Atacama Cosmology Telescope (ACT)
anomalous microwave emission (AME)
Arcminute Microkelvin Imager (AMI)
angular power spectrum
baryon acoustic oscillations (BAO)
Cosmic Background Imager (CBI)
cosmic background radiation (CBR)
cosmic infrared background (CIB)
cosmic optical background (COB)
Cosmic Background Explorer (COBE)
extragalactic background light (EBL)
epoch of reionization (EOR)
Galactic Emission Mapping (GEM)
gravitational wave background (GWB)
initial fluctuation spectrum
magnetic energy spectrum
maximum likelihood mapmaking
primordial gravitational waves
spectral energy distribution (SED)
Simons Observatory (SO)
spinning dust emission
South Pole Telescope (SPT)
surface brightness (SB)
surface of last scattering
Sachs-Wolfe effect (SWE)
Sunyaev-Zel'dovich Array (SZA)
Sunyaev-Zel'dovich effect (SZ effect)
thermal dust emission
Thomson optical depth (τT)
time-ordered data (TOD)
Very Small Array (VSA)
weak lensing (WL)
Wilkinson Microwave Anisotropy Probe (WMAP)