Science lied to us, wittingly or not, about planetary cores consisting of super-heavy molten minerals and metals. In Truth, as we have found on every single world we visited - and our own Earth as well, once we learned how to look for it - there is a Black Hole at the centre of every planet.
And unknown to most, fiercely kept from the public, since the knowledge itself heralds nothing but existential dread and raving madness, it is the same Black Hole we find in all of them.
Meta-scientists have since figured out that that's also where gravity comes from - it is merely a physical manifestation of the inescapable pull of oblivion itself. Pulling us ever downwards, inwards, into Nothingness.
But, you may ask, what about the Black Holes we first observed? The ones out there in space?
There used to be planets around them, too. Those were the worlds where Achlys has already won.
