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Invasion percolation solves Fermi Paradox but challenges SETI projects

  • E. Galera (a1), G. R. Galanti (a1) and O. Kinouchi (a1)

Non-homogeneous fractal-like colonization processes, where the cluster of visited sites has large voids and grows slowly, could explain the negative results of Search for Extraterrestrial Intelligence (SETI) preserving the possibility of a galactic spanning civilization. Here we present a generalized invasion percolation model to illustrate a minimal colonization process with large voids and delayed colonization. Spatial correlation between unvisited sites, in the form of large empty regions, suggests that to search civilizations in the Sun neighbourhood may be a misdirected SETI strategy. A weaker form of the Fermi Paradox also suggests this last conclusion.

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Author for correspondence: O. Kinouchi, E-mail:
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Anglada-Escude, G, et al. (2016) A terrestrial planet candidate in a temperate orbit around Proxima Centauri. Nature 536, 437440.
Armstrong, S and Sandberg, A (2013) Eternity in six hours: intergalactic spreading of intelligent life and sharpening the Fermi paradox. Acta Astronautica 89, 113.
Batty, M (1991) Cities as fractals: simulating growth and form. In Crilly, AJ, Earnshow, RA, Jones, H (eds). Fractals and Chaos. New York, NY: Springer, pp. 4369.
Bonfils, X, Astudillo-Defru, N, Diaz, R, Almenara, J-M, Forveille, T, Bouchy, F, Delfosse, X, Lovis, C, Mayor, M, Murgas, F, Pepe, F, Santos, NC, Segransan, D, Udry, S, and Wunsche, A (2018) A temperate exo-Earth around a quiet M dwarf at 3.4 parsecs. Astronomy & Astrophysics (in press), doi: arXiv preprint arXiv:1711.06177, 2017.
Cirkovic, MM (2003a) Cosmic irony: SETI optimism from catastrophes? Contact in Context 2, 16.
Cirkovic, MM (2003b) On the importance of SETI for transhumanism. Journal of Evolution and Technology 13, 114.
Cirkovic, MM (2009) Fermi's paradox-The last challenge for copernicanism? Serbian Astronomical Journal 178, 120.
Crawford, I (2000) Where are they? Scientific American 283, 3843.
Eden, M (1961) A two-dimensional growth process. Dynamics of Fractal Surfaces 4, 223239.
Enriquez, JE, et al. (2017) Breakthrough listen follow-up of the reported transient signal observed at the Arecibo Telescope in the direction of Ross 128. International Journal of Astrobiology 13.
Feng, F, et al. (2017) Color difference makes a difference: four planet candidates around τ ceti. The Astronomical Journal 154, 123.
Gillon, M, et al. (2017) Seven temperate terrestrial planets around the nearby ultracool dwarf star. Nature 542, 456460.
Hair, TW and Hedman, AD (2013) Spatial dispersion of interstellar civilizations: a probabilistic site percolation model in three dimensions. International Journal of Astrobiology 12, 4552.
Haqq-Misra, JD and Baum, SD (2009) The sustainability solution so the Fermi Paradox. Journal of the British Interplanetary Society 62, 4751.
Harp, GR, et al. (2016) SETI observations of exoplanets with the Allen Telescope Array. The Astronomical Journal 152, 181194.
Hart, MH (1975) Explanation for the absence of extraterrestrials on earth. Quarterly Journal of the Royal Astronomical Society 16, 128135.
Hetesi, Z and Regaly, Z (2006) A new interpretation of drake-equation. Journal of the British Interplanetary Society 59, 1114.
Jensen, HJ (1998) Self-organized Criticality: Emergent Complex Behavior in Physical and Biological Systems. Cambridge University Press, Cambridge, UK.
Kinouchi, O (2001) Persistence solves Fermi Paradox but challenges SETI projects arXiv:cond-mat/0112137v1.
Landis, GA (1998) The Fermi paradox: an approach based on percolation theory. Journal of the British Interplanetary Society 51, 163–1166.
Lem, S (1988) Fiasco. Mariner Books, Boston, USA.
Lem, S (1999) His Master's Voice. Northwestern University Press, Evanston, Ilinois, USA.
Lineweaver, CH, Fenner, Y and Gibson, BK (2004) The galactic habitable zone and the age distribution of complex life in the Milky Way. Science 303, 5962.
Morrison, IS and Gowanlock, MG (2015) Extending galactic habitable zone modeling to include the emergence of intelligent life. Astrobiology 15, 683696.
Ramirez, R, et al. (2017) New numerical determination of habitability in the Galaxy: the SETI connection. International Journal of Astrobiology 17, 110.
Rossmo, DK (2017) Bernoulli, Darwin, and Sagan: the probability of life on other planets. International Journal of Astrobiology 16, 185189.
Sheppard, AP, et al. (1999) Invasion percolation: new algorithms and universality classes. Journal of Physics A: Mathematical and General 32, L521L529.
Vukotic, B and Cirkovic, MM (2012) Astrobiological complexity with probabilistic cellular automata. Origins of Life and Evolution of Biospheres 42, 347371.
Ward, PD and Brownlee, DNY (2004) Rare Earth: Why Complex Life is Uncommon in the Universe. Copernicus Books, Springer, Berlin, Germany.
Webb, S (2015) If the Universe Is Teeming with Aliens…Where is Everybody?: Seventy-Five Solutions to the Fermi Paradox and the Problem of Extraterrestrial Life. Springer International Publishing, Springer, Berlin, Germany.
Wilkinson, D and Willemsen, JF (1983) Invasion percolation: a new form of percolation theory. Journal of Physics A: Mathematical and General 16, 33653376.
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International Journal of Astrobiology
  • ISSN: 1473-5504
  • EISSN: 1475-3006
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