"Oceanographer and marine biologist Robert D. Ballard looks back on a long and storied life that includes accomplishments ranging from discovering new life-forms to finding the wreck of the Titanic"--
What frightens us, what unnerves us? What causes that delicious shiver of fear to travel the lengths of our spines? It seems the answer changes every year. Every year the bar is raised; the screw is tightened.