Speculated

The biology on this globe is carbon-based. Some have speculated that there could be silicon-based forms of biology elsewhere in this universe. There yet could be plasma-based biology. There could be incorporeal biology. There could be other probabilities.

In his book Star Maker, Olaf Stapledon speculated that some advanced civilizations elsewhere in this universe do not survive their experimentations with technology of advanced physics.

They reduced Hegel to half-sheets of paper, suggested profanely various readings for Petronius, speculated without reverence on the darker habits of mankind from Aristotle to the Junior Prior.