ANNOUNCEMENTS

1. ANNOUNCEMENTS 1. FINAL EXAM SATURDAY 1:30—4pm IN BESC 180. ONE PAGE OF NOTES + CALCULATOR ALLOWED. THOSE TAKING FINAL EXAM, PLEASE PICK UP REVIEW QUESTIONS FOR FINAL 2. REVIEW SESSION HERE AT FISKE: TODAY, after class 3:30—4:45pm 3. HAPPY WINTER SOLSTICE SEASON !

2. A QUESTION: IF YOU WENT TO THE COSMIC EDGE AND THREW OVER A SPEAR, WHAT WOULD IT DO? HIT THE EDGE AND BOUNCE BACK? (A WALL) GO OVER AN ABYSS ? (A CLIFF) JUST FADE AWAY ? (A MARSH) ALL OF THESE ARE SO RIDICULOUS THAT THERE CANNOT BE A COSMIC EDGE. (DOES THIS IMPLY THAT THE WORLD MUST BE INFINITE?) …BUT THE UNIVERSE CAN NOT BE INFINITE, FILLED WITH AN INFINITY OF STARS BECAUSE IT IS DARK OUT AT NIGHT ! {SAY WHAT ????}

3. THE DARK NIGHT SKY PARADOX: “It is dark outside at night, therefore the Universe is finite in space or time or both” Brief History: 1610: Johannes Kepler “ If the Universe was infinite, the Celestial Vault would be as luminous as the Sun.” 1700: Edmund Halley…what he said 1744: J.P. Cheseaux: Darkness due to dust in space absorbing the light 1823: Heinrich Olbers…what he said 1848: John Herschel: “…but absorbing gas would heat up and glow.” 20th Century: many textbooks stated that expansion of Universe makes night sky dark 20th Century: Ed Harrison, Jim Gunn, et al. “look-back time through the Universe exceeds the luminous lifetime of galaxies  The Universe is finite in TIME !!!

4. Farthest galaxies: light was emitted nearly 13 billion years ago …. Still there is darkness surrounding each and every galaxy in this image (there are < one dozen stars in our galaxy in this image)

5. ANALOGIES THAT MIGHT BE HELPFUL UNDERSTANDING “OLBERS’ PARADOX” IMAGINE A FOREST, AN INFINITE FOREST. EVEN IF YOU MAKE THE TREE TRUNCKS REALLY SKINNY, NO MATTER WHICH WAY YOU LOOK YOU CAN NOT SEE PAST THE TREES TO THE CLEARING BEYOND. THIS IS TRUE EVEN IF YOU CANNOT SEE THE SPECIFIC TREE TRUNK BLOCKING YOUR VIEW BECAUSE IT IS TOO FAR AWAY….SOLID WOOD ALL AROUND. 2. IMAGINE THAT THERE ARE AN INFINITE NUMBER OF STARS, ALL OF THE SAME BRIGHTNESS EVENLY DISTRIBUTED THROUGHOUT SPACE. CONSIDER THESE STARS IN RINGS, EACH RING AT THE SAME DISTANCE FROM EARTH. WHILE THE BRIGHTNESS OF THESE STARS DECREASES AS DISTANCE SQUARED, THE NUMBER OF STARS IN EACH RING INCREASES AS DISTANCE SQUARED  TOTAL AMOUNT OF LIGHT FROM EACH RING IS CONSTANT, REGARDLESS OF NEAR OR FAR  INFINITE NUMBER OF RINGS IMPLIES INFINITE AMOUNT OF LIGHT

6. THE MODERN RESOLUTION TO “OLBERS’ PARADOX” • THE FARTHER WE LOOK OUT INTO THE UNIVERSE THE FURTHER WE LOOK BACK IN TIME, due to the finite speed of light • IF THERE WAS A TIME BEFORE WHEN THERE WERE LUMINOUS OBJECTS IN THE UNIVERSE (GALAXIES OF STARS) THEN A “COSMIC EDGE” WOULD BE PRESENT • DARKNESS AT NIGHT IS CREATED IF GALAXIES ARE NOT INFINTIELY OLD  THE UNIVERSE IS FINITE IN TIME, IT HAD A BEGINNING !... This is the modern resolution to Olbers’ Paradox

7. DISTANCES IN SPACE: FIRST STEPS TAKEN BY GREEKS, BUT VASTNESS WAS NOT APPRECIATED….EVEN NEW IDEAS OF MEASUREMENT REQUIRED: THE LIGHT-YEAR: THE DISTANCE LIGHT TRAVELS IN ONE YEAR @ 186,000 MILES PER SECOND. MOON IS 1.5 LIGHT-SECONDS AWAY SUN IS 8.5 LIGHT-MINUTES AWAY SATURN: 30 LIGHT-MINUTES AWAY PLUTO: 2 LIGHT-HOURS ALPHA CENTAURUS (NEAREST STAR BEYOND OUR SOLAR SYSTEM): 4.5 LIGHT-YEARS Sirius: 8 light-years away Pleiades : 400 light-years Galactic Center: 24,000 light-year Size of Milky Way Galaxy: ~ 100,000 light-years across Andromeda galaxy: 2.2 Million Light-years away Most Distant Galaxy Known: 12 Billion light-years away Size of Universe: 13.5 Billion light-years (FINITE!)

8. Modern Cosmology & Cosmogony • SIZE:OUR UNIVERSE IS UNIMAGINABLY LARGE … STRETCHING 13.5 BILLION YEARS BACK INTO TIME (THE “BIG Bang”) AND > 13.5 BILLION-LIGHT-YEARS IN SPACE • EVOLUTION: WE CAN TRACE OUR ORIGINS BACK TO THE CREATION OF SPACE AND TIME, MATTER, ENERGY AND LIGHT IN THE BIG BANG. • CONSCIOUSNESS? WHEN DID IT ARISE AND HOW? IT IS HUMAN CONSCIOUSNESS THAT HAS DEVELOPED MODERN COSMOLOGY & COSMOGONY… a circular argument? • BELIEF & REASON: IS THERE A PLACE FOR ANCIENT WISDOM TRADITIONS IN THE MODERN WORLD? In the future we will be among the ancients. • “ RELIGION WITHOUT SCIENCE IS BLIND; SCIENCE • WITHOUT RELIGION IS LAME” ALBERT EINSTEIN

9. COURSE VIGNETTES

10. WONDERFULLY RICH INDIGENOUS CULTURES… “ALTERNTIVE MODERNITIES” WITH WONDERFUL PEOPLE LIVING RICH AND INTERESTING LIVES

11. ALTERNATIVE MODERNITIES: DO WE GLORIFY THEM? POVERTY, DISEASE, ALCOHOLISM, ILLITERACY, ETC OBVIOUSLY NOT AN EASY LIFE

12. AND YET THEY SEEM HAPPY !!

14. PROUD OF WHO THEY ARE AND…

15. PROUD OF THEIR TRADITIONS , THOUGH DIFFERENT FROM OURS.

16. EACH CULTURE HAS ITS OWN WAY OF INTEGRATING EARTH & SKY THAT SPEAKS TO US IN SOME LARGELY SUBCONSCIOUS WAY…can we afford to lose ANY of these ways?

17. QUESTIONS FOR US TO CONSIDER: • GLOBALIZATION ? THE UP SIDES AND THE DOWN SIDES • HAS POTENTIAL TO INCREASE MATERIAL WELL-BEING OF ALL PEOPLES • OFFERS GLOBAL MARKETPLACE FOR INDIGENOUS GOODS & SERVICES • But • HOMOGENIZES CULTURE: “CULTURAL FLATLAND” • ELIMINATES SOME LANGUAGES AND CULTURES: • “While biologists suggest that perhaps 20% of mammals, 11% of birds and 5% of fish are threatened and botanists anticipate the loss of 10% of flowers, linguists and anthropologists today bear witness to the imminent disappearance of half of the existing languages of the world.” Wade Davis in The Wayfinders. • 2. Can we afford this loss of cultural diversity ? Should we care if “primitive” cultures go extinct ? ALTERNATIVE MODERNITIES ≠ PRIMITIVE CULTURES • 3. Even if we wanted to, what could we do, if anything , to prevent this happening? • 4. Does ancient wisdom matter in the modern world? • All astronomy is “ancient wisdom”… the sky sends us messages from the past, both physically and culturally, if we would only take the time to look.

18. EARTH AT NIGHT “While Mona Lisas and Mad Hatters; Sons of bankers, sons of lawyers; Turn around and say good morning to the nightFor unless they see the sky; But they can't and that is whyThey know not if it's dark outside or light” sung by Elton John