Are there scientific problems that cannot be solved? Mathematics is riddled with such problems, but can we pose analogous questions outside of mathematics? Does nature itself impose fundamental limits on our knowledge of the universe? Despite the work of some of the greatest minds of the twentieth century, no one really knows. In May 1995 this profound and far-reaching concern brought together a small but select group of scientists in a remote scientific outpost in Abisko, Sweden, a village far north of the Arctic Circle. Boundaries and Barriers captures the spiritand the contentof the talks given at the meeting. }Are there scientific problems that cannot be solved? Mathematics is riddled with such problems, but can we pose analogous questions outside of mathematics? Does nature itself impose fundamental limits on our knowledge of the universe? Despite the work of some of the greatest minds of the twentieth century, no one really knows. In May 1995 this profound and far-reaching concern brought together a small but select group of scientists in a remote scientific outpost in Abisko, Sweden, a village far north of the Arctic Circle. Boundaries and Barriers captures the spiritand the contentof the talks given at the meeting. Included are contributions by John Barrow on the limits of science, John Casti on the search for the unknowable in science, James Hartle on quantum cosmology, Harold Morowitz on complexity and epistemology, and six more fascinating chapters that illuminate the possible limits to what we can know by using the tools of science. The issues discussed here challenge the very foundations of science, but the conclusions are optimistic. When the dust clears, science remains standing-our best bet for understanding the way the world works. }