The day that shook the earth

It's been 75 years since the atomic bomb dropped in Hiroshima — this is how the nuke was conceived. Deemed as the 'Trinity nuclear test', it happened on the 16th of July 1945, in New Mexico — and ever since the world has not been the same. For Warren Kozak, from The Wall Street Journal, it brought peace in 1945 and proliferation in decades to follow. Here, he contemplates why.