Is humanity approaching an apocalypse?
Today, a group of international scientists will move the hands of the symbolic "Doomsday Clock" for the first time in two years.
The clock, which is maintained by the Bulletin of the Atomic Scientists, reflects how close civilization is to "catastrophic destruction." First set at seven minutes to midnight, the clock has been moved only 18 times since its creation in 1947.
In 2007, it was changed from seven to five minutes to midnight to reflect the threat of a "second nuclear age" and the challenges presented by global warming. The last time the clock was moved within five minutes of midnight was during the final days of the Cold War in 1984.
The Bulletin, which includes more than a dozen Nobel laureates, has not disclosed any information regarding which way the hands of the clock will move today.
"Some people may be surprised. Others will say, 'That's what I thought,'" said Lawrence M. Krauss, co-chair of the Bulletin's Board of Sponsors and a professor at Arizona State University's School of Earth and Space Exploration and its physics department.
The scientists will announce their decision at 10 a.m. EST in New York City, but anyone with an Internet connection is invited to watch the event online at TurnBacktheClock.org.
Krauss declined to elaborate on the upcoming announcement, but in a recent Scientific American column he wrote, "The clock has served for nearly 65 years as an international symbol of the level of risk that the world faces from nuclear weapons and, more recently, from all potentially globally destructive technologies."
Founded by a group of scientists who worked in the Manhattan Project, the Bulletin of Atomic Scientist initially created the Doomsday Clock to convey the world's vulnerability to nuclear catastrophe.
But over the years, the clock has come to reflect the threats posed by climate change, nuclear terrorism and biological weapons.
Though the matrix of threats has shifted since the clock's inception, security experts say it still maintains its significance.
"I think that the context has dramatically changed since the end of the Cold War. Everyone lived in a certain level of apprehension. ... The nuclear confrontation was salient and palpable," said Bruce Blair, president of the Washington, D.C.-based think tank World Security Institute. "The clock was a shorthand summary of where we stood."
The prospect of nuclear war with Russia is no longer front and center, he said, but other threats have emerged and deserve attention.
Nuclear stalemates with North Korea and Iran and the recent failure to secure an international accord at the climate conference in Copenhagen are three of the greatest threats facing the world right now, he said.
Though he suggested that Obama's leadership and commitment to a nuclear-free world could move the clock one more minute away from midnight, he said, "[These are] three worsening threats that probably will warrant the Bulletin to move the clock forward at least a minute, maybe two."
Spencer Weart, a science historian and former director of the Center for History of Physics at the American Institute of Physics in College Park, Md., said that at this point the clock, in some ways, serves as a reminder of how times have changed.