Technical means do not allow detection of alien life

The argument

The position is not that alien life is impossible but that detecting it is, given the methods available and the distances involved. Each of the three routes that might in principle work fails on the same kind of obstacle. The first is direct observation. Identifying a sign of life on an exoplanet — a river, a city, an artefact — requires an image of the planet itself, and resolving surface features at interstellar range would demand an optical resolution that no telescope positioned within the Solar System can achieve. The limit is not one of engineering refinement but of what an instrument of any buildable size can resolve at that distance. The second is going to look. Sending a probe is impractical for a different reason: the length of travel. Reaching even the outer solar system takes a substantial part of a human lifetime, and anything beyond it is a different order of problem again. A mission whose results would arrive long after the civilisation that launched it had changed beyond recognition is not a usable method of detection. The third is listening. Detecting signals from alien life has been attempted, most prominently by SETI, and the difficulty is that a signal must be strong enough, directed appropriately, and arriving during the window in which someone is listening on the right frequency. The search covers a minute fraction of the possibilities, and nothing has been found. What the three failures share is that they are not provisional. They follow from resolution limits, from travel times and from the weakness of signals across interstellar distance — constraints of physics rather than of current budgets or engineering maturity, and so not the kind of obstacle that a better-funded or more patient effort removes. Proponents of this position conclude that technical means do not allow the detection of alien life, and that detection of or contact with an alien life form is therefore not possible.

Context

With current technology we can only prove if a planet is in a habitable zone but not if it can actually harbour intelligent life.

Premises

Counter-arguments

Some missions to our next Solar System can be physically feasible as Breakthrough Starshot According to Kardashev scale level II or III civilisations can be able to harness such high amount of energies that should be detectable on Earth.

Rejecting the premises

[Rejecting P1] Direct imaging of surface features is not how the search proceeds: transit and emission spectroscopy already measure exoplanet atmospheres, and candidate biosignature gases are detectable at that resolution — so the premise sets an unnecessary standard and then concludes from its impossibility. [Rejecting P2] The premise misstates its own case. Probes to the outer solar system have been flown repeatedly, and proposals such as Breakthrough Starshot address interstellar distances with light-sail craft rather than the crewed timescales the premise assumes. [Rejecting P3] Impractical so far is not impossible. SETI has surveyed a small fraction of the sky across a narrow band of frequencies, and a civilisation harnessing energy on the scale the Kardashev classification describes would leave signatures detectable from Earth — so the record is one of incomplete search rather than of a closed door.