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      Cosmologists say a wide range of
    evidence is forcing them to consider the possibility that an unknown "dark
    energy" exists that is causing the expansion of the universe to accelerate. 
    "The universe is made mostly of dark matter and dark energy," says the Lab's
    Saul Perlmutter, "and we don't know what either of them is."   The concept
    of dark energy is expanded upon in a May 28 Science article titled, "The Cosmic Triangle: Revealing
    the State of the Universe."     
     
      Stopping an underground leak can be
    costly and difficult.  One emerging approach is to inject fluids into the ground that
    gel and form a barrier. Unfortunately, controlling the flow of these fluids has been a
    problem.  Now, researchers are experimenting with ferrofluids that respond to a magnetic
    field.  Ferrofluid barriers could be steered into place by magnets, sealing
    leaking waste tanks, pipes, or landfills with minimum environmental disturbance.
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