To answer the biggest, they first have to find the smallest, the simplest substance that creates atoms itself. Physicists have discovered quarks, it is even smaller particle than electron, it is in fact, the one that made up electrons(they are finding even smaller than quarks through the research of LHC). So small, so unstable and volatile. This if harnessed, could produce devastating impact on the world. Similar to Caesium and Francium, both which is highly unstable, are able to explode a huge bath tub of cold water with a single drop of that chemical property. Imagine the power of quarks, that's a hell lot more than any ordinary atomic bombs ever developed.
They (scientists and physicists)even hypothesized that such volatility could create the next Big Bang or create a black hole in itself, and split the world into half. Some of the panel of skeptics and scientists themselves insists that the reseach of LHC should be stopped before it's too late. Now what the world gonna turn out to be? I don't know..lol