“系外生命”是否存在？（科技大观）

Core Findings - An international team led by astronomer Nikku Madhusudhan from Cambridge University has published findings in the Astrophysical Journal Letters, indicating the discovery of "the strongest evidence yet" for potential life activity in the atmosphere of the exoplanet K2-18b, located approximately 124 light-years from Earth [1] - The atmosphere of K2-18b contains chemical signatures of dimethyl sulfide (DMS) and dimethyl disulfide (DMDS), which on Earth are primarily produced by marine life, suggesting a possible biological origin [1] - This research utilized the James Webb Space Telescope (JWST) to analyze the starlight passing through the planet's atmosphere, revealing the presence of these complex organic molecules, which are more intricate than methane [1] Exoplanet Characteristics - K2-18b is one of the most common types of exoplanets discovered, with a mass approximately 8.6 times that of Earth and a volume about 2.6 times larger, situated within the habitable zone [2] - Previous studies using the Hubble Space Telescope suggested that K2-18b's atmosphere was rich in water vapor, although later analyses indicated that the observed water vapor might actually be methane [2] - The recent study confirmed the presence of methane and carbon dioxide in K2-18b's atmosphere and proposed the existence of dimethyl sulfide for the first time, achieving a detection confidence level of 3.4, which is considered a significant threshold in astronomical observations [2] Scientific Debate - There is skepticism among researchers regarding the findings, with some suggesting that the observational data may be affected by significant noise, and that reported features could be statistical fluctuations [3] - Other models could potentially explain the data with similar or even better fits, raising questions about the existence of water on K2-18b, with some researchers proposing it may resemble a gas giant like Neptune [3] - The possibility that dimethyl sulfide could originate from non-biological processes or interstellar medium has also been raised, indicating that even if detected, these compounds may not necessarily indicate life [3] Future Exploration - Various countries are developing plans to explore exoplanetary life, including China's Tianling Plan and the United States' Habitable Worlds Observatory project, reflecting a growing interest in astrobiology [4] - Advancements in astronomical telescopes, atmospheric modeling, and astrobiology are expected to enhance the understanding of potential life signals in the universe [4]