Manhattan project scientists reflect on atomic age

(CNN) -- Edward Teller and Joseph Rotblatt were two key figures in the Manhattan project -- the research group credited for inventing the U.S.-built nuclear bomb during World War II.

After the war was over, the two men followed very different paths: Teller went on to father the hydrogen bomb, while Rotblatt won a Nobel peace prize for his anti-war efforts.

They recently shared their thoughts on the atomic age they helped usher in half a century ago.

TELLER: "I've been asked again and again, aren't you sorry for the hydrogen bomb? My answer is no, I'm not. I'm even happy about it. And I tell you why: Without me, it would have happened anyway." AIFF   WAV (465K/20 sec. audio)

ROTBLATT: "I do feel responsible ... I don't feel so much guilt but rather shame." AIFF   WAV (240K/11 sec. audio)

TELLER: "The idea of nonproliferation seemed to be wishful thinking. When I heard about the explosion in India, I simply felt that what was inevitable happened." AIFF   WAV (255K/11 sec. audio)

ROTBLATT: "I did foresee this. If nuclear weapons states say that nuclear weapons are needed for security (then) one cannot deny the same security to other countries." AIFF   WAV (305K/14 sec. audio)

TELLER: "What we should have learned is that the world is small, that peace is important and that cooperation in science ... could contribute to peace. Nuclear weapons, in a peaceful world, will have a limited importance." AIFF   WAV (77K/7 sec. audio)

ROTBLATT: "We have to keep putting on the pressure to convince the states that a world without nuclear weapons would be a safer world than the present one. I hope I will see it in my lifetime." AIFF   WAV (456K/20 sec. audio)