The discovery in 1998 that the Universe is actually speeding up its
expansion was a total shock to astronomers. It just seems so
counter-intuitive, so against common sense. But the evidence has
become convincing.
Because most of the objects that astronomers observe are so far away, we
cannot touch them. Observing the light that they emit is often the only
means we have of understanding them. Studying the light that comes from
a source can tell us a great deal about what kind of object it is -- we can
measure the energy of the light coming from the source, we can measure the
amount of light coming from the source, and we can make an image of
the source. If we graph the amount of light at different
energies, we can make a ... قراءة التالي »
Long before experiments could detect
gamma-rays
emitted by cosmic sources, scientists had known that the Universe should be
producing such high energy photons. Hard work by several brilliant scientists had shown us
that a number of different processes which were occurring in the Universe
would result in gamma-ray emission. These processes included cosmic ray
interactions with interstellar gas,
supernova
explosions, and interactions of energetic ... قراءة التالي »
