I was watching a popular TV series on the Universe which briefly described super novae. Here are two naive questions not well answered in the video. 1) When a white dwarf becomes a super nova through accretion of gas from a companion star. the pressure from the accreted material ignites carbon-carbon fusion which explodes the star into a super nova. Why does this carbon-carbon fusion release so much energy and blow the star? 2) For huge stars carbon-carbon fusion apparently is no problem and in fact fusion is able to form elements all the way up to iron. At some point the iron core implodes from its own weight. Why is this? Is this saying that if one builds up an iron ball in space - slowly adding more iron - until the ball is enormous that at some point it will no be able to support itself? Secondly, why is the implosion so violent and where does the energy come from?