Origin of life research is the study of how life came to be as a transition from non-life to life in the vastly different early Earth environment. What happened 4 billion years ago before LUCA? Abiogenesis is the scientific hypothesis for origin of life explaining a natural process by which life arises from non-living matter, such as simple organic compounds. Abiogenesis asks: how did pre-life chemical reactions give rise to life? Ideas such as RNA World hypothesis, “metabolism-first” hypotheses, the 1952 Miller–Urey experiment, Warm Little Pond, and Primordial Soup, seek to answer this question. Panspermia is the idea that life may have originated elsewhere in the universe and came to Earth: amino acids (the building blocks necessary for life) have been found in meteorites, comets, asteroids, and star-forming regions of space.