I personally believe that we'll be hit a technological singularity based
in
an SI within 9 years, but feel free to consider this to be crackpot
monomania on my part. See
http://www.ShireNet.com/~dgc/singularity/singularity.htm
for details.
Now for a more reasoned response:
We appear to be in a decade that is scientifically
similar to the 1890's, in that we believe that we have
a nearly complete understanding of the laws of physics.
Very few phenomena that are actively being investigated
by physicists are unexplained by the "Standard Model."
In the 1890's nearly all phenomena that were being
investigated were explained by the then-current standard
model, consisting of Newton's laws, Maxwell's equations,
and some conservation laws. There were only a very few
things that didn't fit, mostly the "violet catastrophe"
and a few cosmological details. The prevailing attitude
was a belief that only a few details remained to be worked
out.
Within 15 years, the advent of quantum mechanics and
relativity had thrown the world of physics into a ferment.
Now, we can refine your question: what is it that remains
unexplained by the standard model? the answer, according to
all popular accounts, is gravity. We know it's there, and we
know the inverse square law, but we don't see how it works.
Sure, we see many pieces of the puzzle, the most beautiful
piece IMO being general relativity. But the pieces don't
all fit, and they don't fit into the standard model. A whole
bunck of theorists are trying very hard to build a GUT
(Grand Unified Theory) but they appear to represent a minor
ripple on the quiet pond of our overall complacency.
So, again borrowing from "The Physics of Star Trek", by
Krause, if we can learn to manipulate gravity, we can
perhaps get past the hard limits on acceleration and
energy usage that constrain even a modest effort in
space exploration.
That's it for physics. Anyone want to try in another field?