from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. The mass needed to account for the difference between the observed mass of the universe and the mass needed to halt the expansion of the universe.
  • n. The unobserved matter needed for the observed rotation of most galaxies to match theoretical predictions.


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  • I remember that Sunday. I was very, very sick, see, and....

    December 19, 2009

  • The Vatican is investigating.

    December 18, 2009

  • “Dark matter became a serious issue in the 1970s, when Vera Rubin of the Carnegie Institution of Washington and her colleagues charted the rotation speeds of galaxies and found that they seemed to be enveloped in halos of dark matter, then called missing mass.”

    The New York Times, At a Mine’s Bottom, Hints of Dark Matter, by Dennis Overbye, December 17, 2009

    December 18, 2009