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 EXAM before 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 I sp ~10 5 - 10 7 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

6. 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 10 8 m/s The faster you move, the slower time passes The faster you move, the more massive you get

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

16. The Scientific Method 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. (Chapter 2)

17. 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