1. Cosmology Olber’s Paradox Big Bang Development of the Universe

2. Olber’s Paradox Why is the night sky dark?

3. Newton believed universe was infinite in space & time. If the universe contains an infinite number of uniformly distributed stars: 1)The collective brightness received should make sky bright. 2) Every line of sight should eventually lead to the surface of a star 3) Every point in the sky should be as bright as the surface of a star.

4. Apparent b drops with/d 2, but surface A increases with d 2, if stars uniformly distributed, the distance cancels – all equally bright.

5. Olber’s Paradox w math play from 1:53 (4:30 min) http://www.youtube.com/watch?v=0USMjY fkRxshttp://www.youtube.com/watch?v=0USMjY fkRxs http://www.youtube.com/watch?v=gxJ4M7tyLRE Minute Physics Olber’s 4 min

6. Big Bang Resolves paradox. Universe not infinite in space or time. Stars not uniformly scattered. Universe too young for light to have reached us yet. Universe expanding.

7. Big Bang Model Space Time & Laws of Physics born from a singularity ~14-15 BYA. Space time expanding.

8. If all galaxies are moving away: Light from stars is red shifted into the IR region (we would not see it)

10. Big Bang Model Evidence Einstein’s general relativity also contradicts static universe – he tried to introduce cosmic constant! See Doppler Red Shift. Explains Olber’s paradox. Cosmic Background Radiation.

11. Cosmic Background Radiation CSBR. There is microwave radiation in the universe coming from all directions. From Wein’s law can find T of peak radiation ~ 3 K. Universe behaves as black body at 3K. Gas laws suggest universe would be that T if cooled by expansion for 14-15 BY.

12. Evidence Big Bang http://www.youtube.com/watch?v=uyCkADmNdNo

13. Future of the universe Closed – big crunch. Gravity slowing expansion. Open – expansion continues. Not enough matter to overcome expansion. Flat – expansion slows almost to v = 0.

14. Outcome depends amount of mass Critical density  o amt mass needed to stop expansion. Appears we have too little mass but not all mass is visable.

15. Only 10% of mass needed to stop expansion is observed so – open universe. Dark matter - mass cannot be seen. No interaction with light. Affects rotational speed of galaxies. MACHOS - Brown & Black dwarfs –Massive compact halo objects. WIMPS – neutrinos –Weakly interacting massive particles.

16. Dark Matter Dark Energy http://www.youtube.com/watch?v=rLmcbjLVPKc

18. International Research Project outline goals. http://www.spaceref.com/news/viewpr. html?pid=30109http://www.spaceref.com/news/viewpr. html?pid=30109 Herschel http://sci.esa.int/science- e/www/object/index.cfm?fobjectid=321 36