There's four of them, sort of. At least according to the National Academy of Engineering, which convened an international group of tech thinkers to identify the grand challenges facing us in the 21st century. The report was released at today's AAAS annual meeting in Boston. Robert Socolow, mechanical and aerospace engineer at Princeton, reports the list was too subjective to assemble in order. Instead they identified four broad categories of challenges:
(1). environmental wholeness: the need for humans to take care of our earthly home and to be good stewards of the environmental quality that we depend upon (2). our own wellness: the medical side of human life (3). vulnerability: recognition of the fact that we live on a planet that experiences earthquakes and tsunamis, and that we are a species that causes trouble for itself. (4). the joy of living: after you've got health and environmental soundness and you feel protected against the bad side of both human nature and Mother Nature, there is still something else to aspire to: self-knowledge and enlightenment.