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

Examples of background radiation in a Sentence

Recent Examples on the Web

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. 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. 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. 2018

These 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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First Known Use of background radiation

1968, in the meaning defined above

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The first known use of background radiation was in 1968

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