1 / 73

ASTR/GEOL 3300: ET Life

ASTR/GEOL 3300: ET Life. Logistics: Final exam is Monday December 13! Bring your notes, books, etc. 1:30 – 4:00 pm here. Final papers due to me electronically AT THE FINAL EXAM before 5pm ! Our Last Day IS THIS FRIDAY: Pick up old work & paper reviews!!!!!!

ivor-davis
Download Presentation

ASTR/GEOL 3300: ET Life

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ASTR/GEOL 3300: ET Life • Logistics: • Final exam is Monday December 13! Bring your notes, books, etc. • 1:30 – 4:00 pm here. • Final papers due to me electronically AT THE FINAL EXAMbefore 5pm! • Our Last Day IS THIS FRIDAY: • Pick up old work & paper reviews!!!!!! • We will finish our discussion of interstellar travel. • Then, Fermi’s Paradox • Implications of the Search • UFOs

  2. Pick up more reviews please Brandt, Grudzinski, Gray, Okonowsky, Townsend, Trohman, Ely, Uhle, Collette, Kaspyrzk, Rynning, McCollom, McNeill, Watson, Hazlitt, Fairbanks, Hecht, Lewis, Melville

  3. Matter/Antimatter • Isp ~105 - 107 • Might work at ~100% efficiency, mass required is reasonable • No real designs, many enormous hurdles (containment, production, radiation, efficiency) • 100 billion dollars for 1 mg!

  4. RECALL • This is for a 1000 year, one-way voyage to the nearest star. • Are there ways to do this without carrying the propellant with you? • Space is not quite empty

  5. Relativity and other weirdness • No matter who you are or where you are, how fast you’re moving and in what direction, the speed of light in vacuum always appears the same to you. • Whoa, but this has been verified many times • You can’t go more than 3 x 108 m/s • The faster you move, the slower time passes • The faster you move, the more massive you get

  6. 4 ly 10 ly 50 ly 150 ly 20,000 ly 2,000,000 ly 106 ly Perceived travel times To where? How long (to traveler) ? How far? • Alpha Centauri • Epsilon Eridani • Deneb • Pleides • Center of Milky Way • Andromeda galaxy • Virgo cluster • 2.5 y • 5 y • 10 y • 15 y • 21 y • 28 y • 30 y

  7. The Scientific Method (Chapter 2) • Science seeks natural explanations for observed phenomena: • Explanations rely solely on natural causes. • "Miracles" are not allowed. • Science advances by developing and testing hypotheses (models). • A scientific model must make testable predictions. • If tests show that the predictions are false, the model must be revised or abandoned. • Occam's Razor: • The simplest scientific model that fits all the observations is most likely the right one.

  8. Incorrect Scientific Practice • Pseudoscience ("false science"): • Masquerades as science, but does not follow the scientific method. • Commonly based on adherent belief. • Cannot be shown to be false to the satisfaction of practitioners. • Unfortunately, there are many, many, many examples.... "Extraordinary claims require extraordinary evidence." - Carl Sagan

  9. The Cosmic Calendar The Universe Is Old, So… • First civilizations might have arisen ~5 Byr after galaxy formed: • Mid-June on CC. • If 1/1,000,000 stars has civilization, a new civilization arises each 60,000 yr! • Each 3 min on CC. (Book says Aug. 14)

  10. Fermi’s Paradox:Where Is Everybody?

  11. The Coral Model of Galactic Colonization • Coral Model: • Advanced beings (or self-replicating machines) are sent from home planet to build colonies; • Each colony sends out more colonies. • Entire galaxy is colonized “quickly”: • ~105 yr at 0.9 c • ~107 yr at 0.1 c • ~108 yr at 0.01 c

  12. Where Is Everybody?Possible Solutions to Fermi’s Paradox • We are alone: • Civilizations are very rare & we may be the first. • Civilizations have not colonized: • Technological difficulties: • Interstellar travel is too hard or expensive. • Sociological considerations: • Other societies choose not to colonize. • Self-destruction: • Civilizations do not survive long enough to colonize. • Civilizations do not wish to reveal themselves: • Zoo Hypothesis: • They are watching us… • Sentinel Hypothesis: • Devices are standing by until we’re ready…

  13. Implications of the Search

  14. Intelligent Life: Poll • When will humans find convincing evidence of intelligent extraterrestrial life? • In the next 20 years. • In the next century. • In the next millennium. • In the even more distant future. • Never--there is probably no other intelligent life out there to find.

  15. Microbial Life: Poll • Will humans eventually find convincing evidence of microbial extraterrestrial life in our solar system? • Yes, probably just at Mars. • Yes, probably just at Europa. • Yes, at Mars & Europa (at least). • There is probably no microbial extraterrestrial life in our solar system. • I just don’t know.

More Related