I want to know abot cosmic microwave background?

Answer 1

http://www.sciam.com/print_version.cfm?articleID=0009F0CA-C523-1213-852383414B7F0147
http://universeadventure.org/
http://en.wikipedia.org/wiki/Physical_cosmology
http://www.astro.ucla.edu/~wright/cosmo_01.htm
http://map.gsfc.nasa.gov/m_uni.html

the cosmic microwave background comes from a time when the universe was about 380 000 years old, and we see it in every direction we look, but the universe was much smaller then. about 380 000 years after the big bang, the universe had expanded and cooled enuf for electrons to combine with atomic nuclei to form atoms (about 74 percent hydrogen and 26 percent helium). light was then able to pass unscattered by the free electrons so the universe became transparent. before this, the universe was much like a heavy fog. we see this light today stretched to microwave wavelengths. its spectrum shows a blackbody temperature of 2.7 kelvins. that is 2.7 degrees centigrade above absolute zero.

anything with a cosmic redshift of 1.7 is far enuf away that the expansion of the universe is carrying it away at light-speed, c. the red shift of the cmb is 1089 so it seems to be receding at my times c. redshift has three causes: 1) the rapid recession of a light source, 2) an extremely massive and dense light source, and 3) the stretching of spacetime due to the expansion of the universe.

the cmb seems to be at least 46 billion light years away, yet the universe is only 13.7 billion years old.

Answer 2

The cosmic microwave background is the afterglow radiation left over from the hot Big Bang. Its temperature is extremely uniform all over the sky. However, tiny temperature variations or fluctuations (at the part per million level) can offer great insight into the origin, evolution, and content of the universe.

Answer 3

In cosmology, the cosmic microwave background radiation (most often abbreviated CMB but occasionally CMBR, CBR or MBR, also referred as relic radiation) is a form of electromagnetic radiation discovered in 1965 that fills the entire universe. It has a thermal 2.725 kelvin black body spectrum which peaks in the microwave range at a frequency of 160.4 GHz, corresponding to a wavelength of 1.9 mm. Most cosmologists consider this radiation to be the best evidence for the hot big bang model of the universe.

The cosmic microwave background is isotropic to roughly one part in 100,000: the root mean square variations are only 18 µK.[1] The Far-Infrared Absolute Spectrophotometer (FIRAS) instrument on the NASA COsmic Background Explorer (COBE) satellite has carefully measured the spectrum of the cosmic microwave background. FIRAS compared the CMB with a reference black body and no difference could be seen in their spectra. Any deviations from the black body form that might still remain undetected in the CMB spectrum over the wavelength range from 0.5 to 5 mm must have a weighted rms value of at most 50 parts per million (0.005%) of the CMB peak brightness.[2] This made the CMB spectrum the most precisely measured black body spectrum in nature.

The cosmic microwave background is a prediction of Big Bang theory. In the theory, the early universe was made up of a hot plasma of photons, electrons and baryons. The photons were constantly interacting with the plasma through Thomson scattering. As the universe expanded, adiabatic cooling (of which the cosmological redshift is an on-going symptom) caused the plasma to cool until it became favourable for electrons to combine with protons and form hydrogen atoms. This happened at around 3,000 K or when the universe was approximately 380,000 years old (z=1088). At this point, the photons did not scatter off of the now neutral atoms and began to travel freely through space. This process is called recombination or decoupling (referring to electrons combining with nuclei and to the decoupling of matter and radiation respectively).

The photons have continued cooling ever since; they have now reached 2.725 K and their temperature will continue to drop as long as the universe continues expanding. Accordingly, the radiation from the sky we measure today comes from a spherical surface, called the surface of last scattering, from which the photons that decoupled from interaction with matter in the early universe, 13.7 billion years (13.7 G yr) ago, are just now reaching observers on Earth. The big bang suggests that the cosmic microwave background fills all of observable space, and that most of the radiation energy in the universe is in the cosmic microwave background, which makes up a fraction of roughly 5×10-5 of the total density of the universe.[3]

Two of the greatest successes of the big bang theory are its prediction of its almost perfect black body spectrum and its detailed prediction of the anisotropies in the cosmic microwave background. The recent Wilkinson Microwave Anisotropy Probe has precisely measured these anisotropies over the whole sky down to angular scales of 0.2 degrees.[4] These can be used to estimate the parameters of the standard Lambda-CDM model of the big bang. Some information, such as the shape of the Universe, can be obtained straightforwardly from the cosmic microwave background, while others, such as the Hubble constant, are not constrained and must be inferred from other measurements
Timeline of the CMB
Important people and dates
1940 Andrew McKellar The observational detection of an average bolometric temperature of 2.3 K based on the study of interstellar absorption lines is reported from the Dominion Observatory, British Columbia [6]
1946 Robert Dicke predicts ".. radiation from cosmic matter" at <20 K, but did not refer to background radiation [7]
1948 George Gamow calculates a temperature of 50 K (assuming a 3-billion year old Universe)[8], commenting it ".. is in reasonable agreement with the actual temperature of interstellar space", but does not mention background radiation.
1948 Ralph Alpher and Robert Herman estimate "the temperature in the Universe" at 5 K. Although they do not specifically mention microwave background radiation, it may be inferred.[9]
1950 Ralph Alpher and Robert Herman re-re-estimate the temperature at 28 K.
1953 George Gamow estimates 7 K.[7]
1956 George Gamow estimates 6 K.[7]
1960s Robert Dicke re-estimates a MBR (microwave background radiation) temperature of 40 K [7]
1964 A. G. Doroshkevich and Igor Novikov publish a brief paper, where they name the CMB radiation phenomenon as detectable.
1964-65 Arno Penzias and Robert Woodrow Wilson measure the temperature to be approximately 3 K. Robert Dicke, P. J. E. Peebles, P. G. Roll and D. T. Wilkinson interpret this radiation as a signature of the big bang.
1990 FIRAS measures the black body form of the CMB spectrum with exquisite precision.
1992 COBE DMR reveals the primary temperature anisotropy for the first time.
2002 Polarization discovered by DASI[

Answer 4

Leftover radiation from the big bang. Look up 'WMAP'.

Answer 5

WHAT IS THE INTERNET FOR.