ground state of the nearest-neighbor quantum spin S= 1/2 Heisenberg antiferromagnet on
the kagome lattice. We study this model on numerous long cylinders with circumferences up
to 12 lattice spacings. Through a combination of very-low-energy and small finite-size
effects, our results provide strong evidence that, for the infinite two-dimensional system, the
ground state of this model is a fully gapped spin liquid.