The Doomsday Clock has remained at 90 seconds to midnight for a second year in a row. Clips with Rachel Bronson, President and CEO of the Bulletin of the Atomic Scientists and Alex Glaser, Princeton University professor.

The Doomsday Clock has remained at 90 seconds to midnight for a second year in a row. Clips with Rachel Bronson, President and CEO of the Bulletin of the Atomic Scientists and Alex Glaser, Princeton University professor.