Fractional distillation

摘要

If you thought the Higgs boson was elusive, consider the case of dark matter. The Higgs-the particle that gives other subatomic species mass-was predicted in 1964 but actually nabbed only last year. That 48-year hunt, though, was a breeze compared with the one for dark matter. Physicists have known the stuff must exist since 1933, when Fritz Zwicky, a Swiss astrophysicist, coined the term to describe a substance which cannot be seen but without which visible galaxies would fly apart as they rotate. The latest results from the European Space Agency's Planck satellite suggest it makes up 85% of all the matter in the universe (up from an earlier estimate of around 80%).