“Most promising signs yet” of alien life on a planet beyond our Solar System

Reported Finding on K2-18b

• JWST spectra of K2‑18b (a cool, likely ocean-bearing exoplanet) show methane and CO₂ plus a tentative signal of dimethyl sulfide (DMS) and dimethyl disulfide (DMDS), gases that on Earth are strongly associated with marine life.
• The DMS/DMDS detection is currently at ~3‑sigma significance (≈0.3% chance of being noise), below the ~5‑sigma bar usually expected for a “discovery.”
• The planet’s hydrogen‑rich atmosphere and position in the habitable zone make liquid water and some form of chemistry-rich environment plausible, but its conditions are very unlike Earth’s.

Statistical and Methodological Skepticism

• Multiple comments stress that 3‑sigma is not “very low” false-positive risk and could be improved only with more observation time or better instruments.
• One detailed critique argues possible “p‑hacking”: fitting a weak spectrum against a small, handpicked set of candidate molecules (including speculative biosignatures), while ignoring a much larger space of plausible infrared‑active gases.
• Others reply that early, somewhat noisy detections are acceptable as hypothesis generators, provided follow‑up work is done and caveats are clear.

Abiotic DMS and Biosignature Ambiguity

• Several links point to detections of DMS in comets and the interstellar medium and to work arguing for efficient abiotic production, undermining “only from life” claims.
• Counterpoints note that sustaining ppm–level DMS/DMDS in a large atmosphere may still be hard to explain without biology, especially without abundant H₂S, but this remains unsettled.
• Many emphasize the need for multiple independent biomarkers and much better lab data on cross‑sections and abiotic pathways.

Media, Hype, and Scientific Communication

• Strong criticism of headlines that drop qualifiers like “promising signs” and of press outreach that leans into “ALIENS?!” while the paper itself is careful and tentative.
• Some argue sensational coverage erodes trust; others say it at least gets people to read about real science.

Broader Context: Life, Fermi, and Travel

• Long side discussions cover: life vs intelligent life rarity, the Great Filter, dark‑forest vs cooperation scenarios, and whether quiet skies imply short‑lived civilizations.
• Many note that even nearby exoplanets are unimaginably far (hundreds of trillions of km), making visits effectively impossible with foreseeable propulsion, so atmospheric spectroscopy may be our main tool for a long time.