How successful can the scalar-tensor theory be in understanding the
  accelerating universe?
  The accelerating universe is closely related to today's version of the
cosmological constant problem; fine-tuning and coincidence problems. We show
how successfully the scalar-tensor theory, a rather rigid theoretical idea,
provides us with a simple and natural way to understand why today's observed
cosmological constant is small only because we are old cosmologically, without
fine-tuning theoretical parameters extremely.
