Pale Blueberry Dot
Someone wondered what would happen if the Earth was instantly replaced with an equal volume of blueberries. So Anders Sandberg worked it out:
The result is that blueberry earth will turn into a roaring ocean of boiling jam, with the geysers of released air and steam likely ejecting at least a few berries into orbit (escape velocity is just 4.234 km/s, and berries at the initial surface will be even higher up in the potential). As the planet evolves a thick atmosphere of released steam will add to the already considerable air from the berries.
It's well worth reading for an example of how seemingly weird or frvialous questions can lead into areas you hadn't even contemplated.