Since the late 19th century, scientists have speculated about what life might look like beyond the Earth. Since carbon-based life-forms here on Earth represent life as we know it, what about critters based on different chemistries? For example, if living things evolved on other worlds based on silicon, ammonia, boron, or nitrogen-alien chemistries suggested by respected space researchers-would we even recognize them as living organisms?
In the 1890s, German astrophysicist Julius Scheiner was the first person to imagine silicon as the basis for extraterrestrial organisms. Such creatures, he speculated, might appear as animated crystals to human eyes. They might also appear as loosely spun threads, like living fiberglass, woven together within a delicate architecture.
In 1893, chemist James Emerson Reynolds gave an unusual lecture at a meeting of the British Association for the Advancement of Science. The lecture was a review of evidence he found that showed that silicon compounds-being resistant to high temperatures-could serve as the basis for life on broiling planets that would quickly destroy Earth-based life.
Science fiction writer H. G. Wells dabbled in the silicon-life idea, too. Also joining Scheiner and Reynolds in the 1890s-a decade fertile in both scientific and sci-fi speculations about exobiology-Wells wrote his classic alien invasion tale "The War of the Worlds".
The year before Wells penned the classic that would inspire Orson Welles' Halloween 1938 radio broadcast and several movies, he wrote a short, science-fact article for the Saturday Review about what he termed "another basis for life".
According to Wells, "One is startled towards fantastic imaginings by such a suggestion: visions of silicon-aluminum organisms. Why not silicon-aluminum men at once? Wandering through an atmosphere of gaseous sulphur, let us say, by the shores of a sea of liquid iron some thousand degrees or so above the temperature of a blast furnace..."