dark matter
Word Rarity
Uncommon
Frequency: Zipf frequency 4.88 in modern English
17
Scrabble Score
10
Letters
4
Syllables
7
Unique Chars
Meaning
noun
Matter which cannot be detected by its radiation but whose presence is inferred from gravitational effects.
Uncountable
noun
Matter which has mass but which does not readily interact with normal matter except through gravitational effects.
Uncountable
Example Sentences
- "The evidence for dark matter in galaxies started to accumulate in the mid-1970s. By the following decade it became clear that essentially all galaxies, including our own Milky Way, are surrounded by extensive halos of dark matter."
- "On large scales like that of clusters of galaxies, gravitational lensing indicates that the dark matter is smoothly distributed, on the average."
Etymology
The term is often said to have been coined in 1933 by the Swiss astronomer Fritz Zwicky in German (as Dunkle Materie), but it had already been in use for decades, in French (matière obscure) by Henri Poincaré as early as 1906, and in English. In contrast to these earlier authors, Zwicky used the term to refer to the apparent mass needed to account for galaxy clusters, where the mass of luminous matter did not add up to enough of a gravitational effect, which led him to infer the existence of nonluminous matter to account for the missing mass. The term gained new popularity in the 1970s as a result of Vera Rubin's publishing (in English) her discovery that some galaxies did not seem to have enough mass to account for their rotation curves.