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Galactic civilizations: Population dynamics and interstellar diffusion
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Author and Affiliation:
Newman, W. I.(Cornell Univ., Ithaca, NY, United States)
Sagan, C.(Cornell Univ., Ithaca, NY, United States)
Abstract: The interstellar diffusion of galactic civilizations is reexamined by potential theory; both numerical and analytical solutions are derived for the nonlinear partial differential equations which specify a range of relevant models, drawn from blast wave physics, soil science, and, especially, population biology. An essential feature of these models is that, for all civilizations, population growth must be limited by the carrying capacity of the environment. Dispersal is fundamentally a diffusion process; a density-dependent diffusivity describes interstellar emigration. Two models are considered: the first describing zero population growth (ZPG), and the second which also includes local growth and saturation of a planetary population, and for which an asymptotic traveling wave solution is found.
Publication Date: Dec 01, 1978
Document ID:
19790011801
(Acquired Nov 15, 1995)
Accession Number: 79N19972
Subject Category: ASTROPHYSICS
Report/Patent Number: NASA-CR-158245, CRSR-711
Document Type: Technical Report
Publisher Information: United States
Contract/Grant/Task Num: NGR-33-010-101
Financial Sponsor: NASA; United States
Organization Source: Cornell Univ.; Center for Radiophysics and Space Research.; Ithaca, NY, United States
Description: 89p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: No Copyright
NASA Terms: EXOBIOLOGY; EXTRATERRESTRIAL LIFE; POPULATION THEORY; ANALYSIS (MATHEMATICS); COLONIES; DIFFUSION; GALAXIES; MATHEMATICAL MODELS; POTENTIAL THEORY; WAVE FRONTS
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