# Black body, white noise

**URL:** <https://boards.straightdope.com/t/black-body-white-noise/466>\
**Category:** Cecil's Columns/Staff Reports\
**Created:** [January 22, 2000, 12:53pm UTC](https://boards.straightdope.com/t/black-body-white-noise/466 "2000-01-22T12:53:00Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![pqlier](https://avatars.discourse-cdn.com/v4/letter/p/439d5e/32.png) [@pqlier](https://boards.straightdope.com/u/pqlier)\
**Post date:** [January 22, 2000, 12:53pm UTC](https://boards.straightdope.com/t/black-body-white-noise/466/1 "2000-01-22T12:53:00Z")

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Surely, you jest.

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**Author:** ![JillGat](https://avatars.discourse-cdn.com/v4/letter/j/9fc29f/32.png) [@JillGat](https://boards.straightdope.com/u/JillGat)\
**Post date:** [January 22, 2000, 7:50pm UTC](https://boards.straightdope.com/t/black-body-white-noise/466/2 "2000-01-22T19:50:00Z")

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And your point is…?

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**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\
**Post date:** [January 24, 2000, 6:13am UTC](https://boards.straightdope.com/t/black-body-white-noise/466/3 "2000-01-24T06:13:00Z")

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A black body has two meanings: First, in general, a black body is just an unknown “item” which might change something from state “A” to state “B”, but how it works inside is inconsequential. For example, your computer is a black box to most: garbage in, garbage out.

In physics, in brief, a black body can also mean a perfect radiator. A black body is assumed to reflect no light which means it absorbs 100% of all light incident upon it. Likewise, a black body will emit off 100% of all radiation it has absorbed.

White noise refers to the fact that you are receiving all wavelengths - typically in the radiowave end of the elctromagnetic spectrum. Similar to how the presence of all visible light combines to form “white light”, the various radio frequencies are said to combine, in a sense, to yield “white noise”.

Well, that’s it in a nut-shell.

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**Author:** ![JillGat](https://avatars.discourse-cdn.com/v4/letter/j/9fc29f/32.png) [@JillGat](https://boards.straightdope.com/u/JillGat)\
**Post date:** [January 23, 2000, 9:53pm UTC](https://boards.straightdope.com/t/black-body-white-noise/466/4 "2000-01-23T21:53:00Z")

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Does this relate to a column by Cecil, or should I move it to General Questions?  
Jill