Cosmic Ray Background Frequency ``` Name: Richard A. Status: other Grade: other Country: USA Date: Summer 2012 ``` Question: What is the frequency in MHz for the cosmic background radiation? Replies: Dear Richard, Good question, even better as I tried to get you a figure. At first I found The background radiation is mostly in the range from 3 x 10 to the 8th to 3 x 10 to the 11th Hz. It was discovered in space in 1965. According to a "Dr. SETI" on the web, there is a peak in the amplitude of the cosmic background radiation, which occurs at about 179.5 GHz. Other sources (specifically http://www.physicsforums.com/showthread.php?t=154531) offer 282 GHz as the peak frequency. Yet another source has 160.2 GHz. I am sorry that the number is not entirely accepted! According to the Wikipedia article on WMAP, the current expansion rate of the universe is 70.5 +/- 1.3 km/se (to the -1) . megaparsec (to the minus 1). I hope this is helpful! The background radiation corresponds to a temperature of 2.73K, or just above absolute zero. Sincerely David H. Levy Hi Richard, From this Wikipedia article: http://en.wikipedia.org/wiki/Cosmic_microwave_background_radiation “Precise measurements of cosmic background radiation are critical to cosmology, since any proposed model of the universe must explain this radiation. The (Cosmic Microwave Background Radiation) CMBR has a thermal black body spectrum at a temperature of 2.725 K, which peaks at the microwave range frequency of 160.2 GHz, corresponding to a 1.873 mm wavelength.” Sincere regards, Mike Stewart Hi Richard, Assuming blackbody radiation, the thermal energy will peak at some wavelength, w. That w will vary proportionately with temperature, Wien's constant, .002898m/k. Planck's Law, E = hv, allows this special case for short wavelength thermal radiation, using the rate of Wien's Constant = Temp * w . We know the cosmic thermal background temperature from measurements, 2.7K. br> so : w = .002898 mK / 2.7K = .00107m and v = 300**6m/s/.00107m = 279GHz = 279000MHz With error, I would give it 300GHz +/- 50GHz. I believe this is in the extremely high frequency range, microwaves. Hope this helps! PEHughes, Ph.D. Milford, NH The cosmic background radiation (also called the cosmic microwave background [CMB]) is actually a range of frequencies following, very accurately, the theoretical “black body radiation” at a temperature of To = 2.725 +/- 0.002 kelvin at the present time. This background radiation peaks at a frequency of 160.2 ghz. FYI: 1ghz = 1000 mhz, so 160.2 ghz = 160.2 x 1000 mhz. The references above will provide you with details about CMB radiation. This agreement between theory and experiment is one of the most precise and accurate arguments for the “Big Bang” model for the creation of the Universe. It is difficult for “Creationists” to find a credible explanation for the creation of the Universe. Vince Calder Click here to return to the Astronomy Archives

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