BY BOTTLING the Universe in a computer, astronomers believe they have divined
what makes galaxies cluster together: cold dark matter and the cosmological
constant.
Carlos Frenk of the University of Durham and his colleagues ran a series of
simulations tracking the motion of a billion galaxies. As Frenk reported at
Britain鈥檚 National Astronomy Meeting in Guernsey last week, the simulation only
produced a realistic pattern of galaxies if two assumptions were made about the
Universe: that it is inhabited by cold dark matter and that there is a
mysterious force鈥攖he cosmological constant鈥攖hat stretches space.
鈥淲hen you don鈥檛 have the cosmological constant, nothing really works well,鈥�
says Frenk. 鈥淚t doesn鈥檛 look anything like the real Universe.鈥�
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