  The possibility that the Fermi scale is the only fundamental energy scale of
Nature is under serious consideration at present, yet cosmic rays may already
have provided direct evidence of new physics at a much higher scale. The recent
detection of very high energy particles with no plausible astrophysical sources
suggests that these originate from the slow decays of massive particles
clustered in the halo of our Galaxy. Such particles had in fact been predicted
to exist beforehand with mass and lifetime in the range required to explain the
observations. I discuss recent work focussing on experimental tests of this
speculative but exciting idea.
