Panspermia

Panspermia boldly asserts that life on Earth arrived via bacteria-laden comets or space dust, challenging the dominant abiogenesis narrative championed by less contrarian theories. Fred Hoyle and Chandra Wickramasinghe's 1970s calculations showed that interstellar dust grains could shield microbes from UV radiation for up to 1 million years, making interplanetary travel plausible. Yet a 2022 study on Earth's earliest fossils, dated at 3.5 billion years, found that 90% of their organic markers are consistent with local synthesis rather than extraterrestrial origin.