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background radiation

noun

Definition of background radiation

: the microwave radiation pervading the universe that exhibits a corresponding blackbody temperature of 2.7 K and that is the principal evidence supporting the big bang theory

— called also cosmic background radiation

Recent Examples on the Web

//Many readings in the buffer zone were no higher than natural background radiation values.
— Vincent Carroll, The Denver Post, "Carroll: Should you be worried about that Rocky Flats soil sample? Let’s put it in perspective.," 18 Oct. 2019
//Researchers found that fluctuations in the background radiation did correspond to clumps of matter.
— Smithsonian, "Three Win Physics Nobel for Showing Our Place in the Cosmos," 9 Oct. 2019
//Then the sky would have reddened, before slowly dimming into pitch darkness; there was simply nothing else there to produce visible light, as the wavelengths of the background radiation continued to stretch through the infrared spectrum and beyond.
— Davide Castelvecchi, Scientific American, "The Quest to Unlock the Secrets of the Baby Universe," 26 Aug. 2019
//Russian state weather monitors reported heightened background radiation levels around the site and beyond.
— Ankit Panda, The New Republic, "The Absurd Strategy Behind Russia’s Nuclear Explosion," 21 Aug. 2019
//The radiation level of 2 microsieverts per hour is only slightly higher than the natural background radiation, which could vary between 0.1 and 0.4 microsieverts per hour.
— Washington Post, "5 Russian nuclear engineers buried after rocket explosion," 12 Aug. 2019
//The National Academy of Sciences on Monday published all three studies — on background radiation, food, and crater sediments.
— Susanne Rust, Los Angeles Times, "Radiation in parts of the Marshall Islands is far higher than Chernobyl, study says," 15 July 2019
//The area of the exclusion zone with above-background radiation levels has also shrunk considerably.
— John Timmer, Ars Technica, "An insider’s perspective on Fukushima and everything that came after," 5 Oct. 2018
//Early in the 20th century, many scientists believed background radiation levels on Earth diminished at higher altitudes.
— Mark Johnson, Milwaukee Journal Sentinel, "Blazing a trail: UW professor's dream leads to breakthrough in identifying origin of cosmic rays," 12 July 2018