Possible Scenarios for Homochirality on EarthMichiya Fujiki In 1978, Fred Hoyle proposed that interstellar comets carrying several viruses landed on Earth as part of the panspermia hypotheses. With respect to life, the origin of homochirality on Earth has been the greatest mystery because life cannot exist without molecular asymmetry. Many scientists have proposed several possible hypotheses to answer this long-standing L-D question. Previously, Martin Gardner raised the question about mirror symmetry and broken mirror symmetry in terms of the homochirality question in his monographs (1964 and 1990). Possible scenarios for the L-D issue can be categorized into (i) Earth and exoterrestrial origins, (ii) by-chance and necessity mechanisms, and (iii) mirror-symmetrical and non-mirror-symmetrical forces as physical and chemical origins. These scenarios should involve further great amplification mechanisms, enabling a pure L- or D-world. |
Common terms and phrases
achiral aggregates amino acids amplification Angew assemblies asymmetric autocatalysis asymmetric synthesis atoms catalyst Chem chemical chemistry chiral chiral molecules circularly polarized light complex compounds corresponding coumarin CrossRef crystals dependence detected determined direction Earth effect electrons emergence enantiomeric excess enantiomers enantioselective energy evolution example experimental experiments field Figure formation formed fractions function groups handedness helical homochirality induced initial interaction irradiation lead Lett liquid magnetic field materials mechanism meteorites mirror mixture molecular molecules Nature observed occur optical activity organic origin parity particles phase Phonolitic Phys physical polymers possible prebiotic present properties PubMed racemic radiation reaction region reported result right-handed rotation sample scenario Science selection showed signals Soai solution solvents spectra spontaneous star structure supramolecular symmetry breaking temperature transition University values violation weak