The
rest
of
the
universe
appears
to
be
made
of
a
mysterious
,
invisible
____________________
called
dark
matter
(
25
percent
)
and
a
force
that
____________________
gravity
known
as
dark
energy
(
70
percent
)
.
Scientists
have
not
yet
____________________
dark
matter
directly
.
It
doesn't
interact
with
____________________
matter
and
it's
completely
invisible
to
light
and
other
forms
of
electromagnetic
radiation
,
making
dark
matter
____________________
to
____________________
with
current
instruments
.
Bust
scientists
are
confident
it
____________________
because
of
the
gravitational
effects
it
appears
to
have
on
____________________
and
____________________
clusters
.
