The Fermi Paradox and the Great Filter: Evaluating Possible Barriers to the Emergence and Survival of Intelligent Civilisations

Charvi Handa, Raghu Raja Mehra

Abstract: The galaxy contains hundreds of billions of stars, most of them older than the Sun, and a large fraction are now known to host planets. Even a slow programme of interstellar expansion should have carried a single civilisation across the galaxy in a few tens of millions of years- a short interval on cosmic timescales. Yet no confirmed sign of any other technological civilisation has ever been detected. This contradiction between reasonable expectation and observed silence is the Fermi Paradox. This paper reviews the paradox and evaluates one of its most influential proposed resolutions: the Great Filter hypothesis, which argues that at least one step on the path from lifeless matter to a long-lived interstellar civilisation must be extraordinarily improbable. The paper sets out the scale of the problem, examines the Drake equation as a framework for organising uncertainty, and evaluates candidate filters both behind us- the origin of life, the emergence of complex cells, multicellularity, intelligence and technology- and potentially ahead of us, including self-destruction, ecological collapse and technological risk. Competing explanations that do not require a filter are also assessed, together with the current state of observational evidence from exoplanet science and the search for extraterrestrial intelligence. The paper argues that the paradox is best treated as an open empirical question, that current evidence does not decide between filter placements, and that the discovery of independent simple life elsewhere would carry unsettling implications for humanity's own prospects.

Keywords: Fermi Paradox, Great Filter, Drake equation, SETI, astrobiology, existential risk, technosignatures, Rare Earth hypothesis

How to Cite?: Charvi Handa, Raghu Raja Mehra, "The Fermi Paradox and the Great Filter: Evaluating Possible Barriers to the Emergence and Survival of Intelligent Civilisations", Volume 15 Issue 9, September 2026, International Journal of Science and Research (IJSR), Pages: 13-18, https://www.ijsr.net/getabstract.php?paperid=SR26831173205, DOI: https://dx.doi.org/10.21275/SR26831173205

Download Citation: APA | MLA | BibTeX | EndNote | RefMan