User blog comment:Tanooki1432/What if.../@comment-202.22.165.171-20110301043710

The first theory is sound and all, up until the "...they're blasted out of the sky by weaponry that is far beyond anything they've seen..." bit. They've had who knows how many hundreds of thousands of years to develop technology, I doubt a few centuries of humans developing weaponry could match the experience and technology of the Reapers.