background radiation
nounDefinition 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
Examples of background radiation in a Sentence
Recent Examples on the Web
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 Professor Mukherjee says that photons from high-energy sources tend to get absorbed by infrared background radiation. — Eoin O'carroll, The Christian Science Monitor, "Neutrino demonstration heralds a new way of observing the cosmos," 12 July 2018 The exposures from the plutonium releases last year were minuscule by comparison, estimated to be a small fraction of the background radiation that every human gets from nature. — Ted Sickinger, OregonLive.com, "Police looking for shooter after one injured in Keizer," 22 Apr. 2018 The exposures from the plutonium releases last year were minuscule by comparison, estimated to be a small fraction of the background radiation that every human gets from nature. — Ted Sickinger, OregonLive.com, "Police looking for shooter after one injured in Keizer," 22 Apr. 2018These example sentences are selected automatically from various online news sources to reflect current usage of the word 'background radiation.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.
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