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Exploring the Longevity of Civilizations: SETI and the Drake Equation

This lecture delves into the longevity of civilizations from a statistical perspective, referencing Richard Gott's Delta t argument. It assesses the probability of civilization timelines, suggesting humans have a future ranging between 256 years to 390,000 years based on past observability. The discussion encompasses the significance of the Drake Equation in estimating the number of extraterrestrial civilizations and contrasts figures from historical human civilizations to potential alien societies. It raises questions about the future of human technological advances in comparison to other intelligent life forms.

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Exploring the Longevity of Civilizations: SETI and the Drake Equation

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Presentation Transcript

  1. Longevity of Civilizations ASTR 1420 Lecture 22 from a Nature paper SETI Debate

  2. Drake Equation (Carl Sagan’s version) N = N* × fplanet× fE× flife× fintell× fciv × fL × × × × N number of transmitting civilizations fplanet fEarth flife N* × × = fintell fciv flong N

  3. Δtargument (Richard Gott 1993, Nature, 363, 315) Past Future Tbegin TNow TEnd If there is an End, where do we stand now in the time axis?

  4. Delta t argument (Richard Gott 1993, Nature, 363, 315) Past Future Tbegin TEnd • t will range between 0 and 1. • Calculates a probability of t being in the first or last 2.5%. • Probability of 0.025 ≤ t ≤ 0.975 ? •  95% • At the 95% confidence level, t will NOT be in the beginning 2.5% or in the ending 2.5% range.

  5. Delta t argument (Richard Gott 1993, Nature, 363, 315) • 0.025 ≤ t ≤ 0.975  • Similarly, at the 99% confidence level Past Future Tbegin TEnd

  6. Delta t argument At 95% confidence! • the length of time something has been observable in the past is a rough measure of its future observability…

  7. History of Human • Homo Sapiens : ≈200,000 years. • 200,000 / 39 < Future < 39*200,000 • 5128 years < Future < 7.8 million years • For our human civilization of 10,000 years • 10,000 / 39 < Future < 39 * 10,000 • 256 years < Future < 390,000 years • Our industrial civilization of ≈200 years • 200 / 39 < Future < 39 * 200 • 5 years < Future < 7,800 years

  8. If aliens are like human 6,400 ≤ N ≤ 9.8 million

  9. In summary… Important Concepts Important Terms • Delta t argument • Statistical approach to the longevity of civilizations • Chapter/sections covered in this lecture : Longevity of Civilization • UFOs : next class!

  10. SETIWill it succeed? ASTR 1420 Section 12.2 + ?

  11. Ernst Mayr • Bioastronomy News (1995, V7, No. 3) • German/American biologist • Harvard Biology Prof. • 7/5/1904 – 2/3/2005

  12. Carl Sagan • Bioastronomy News (1995, V7, No. 4) • We need “functional equivalent of human” not “prevalent humanoids”… • Radio technology  If Aztec civilization survived, would they develop radio technology in several millenia? • We, humanoids, are very young, but we have ~5 billion years to spare in the future. • American Astronomer • Cornell Professor • 11/9/1034 – 12/20/1996

  13. SETI debate Ben Zuckerman Seth Shostak SETI Astronomer • UCLA Astronomy professor

  14. Drake Equation (Carl Sagan’s version) N = N* × fplanet× fE× flife× fintell× fciv × fL × × × × N number of transmitting civilizations fplanet fEarth flife N* × × = fintell fciv flong N

  15. In summary… Important Concepts Important Terms • Logics behind each SETI arguments • Mayr vs. Sagan • Zuckerman vs. Shostak • Statistical approach to the longevity of civilizations • Chapter/sections covered in this lecture : SETI debate

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