What is under bedrock (minecraft)?

A mystery in itself nobody knows what is under the bedrock there's lava or what

I think there's nothing left (a kind of sky just the wrong way round) you fall down and the fall damage is too big…

There's emptiness, you can break down and fall through in the creative bedrock

No, then you fall into 'nothing' and die on it.

Why should that be a mystery? OK

There's just (literally) nothing underneath.

If you can still get down there, you will either be able to teleport yourself in time or you will end up with empty inventory at your respawn point.