This lecture introduces an important concept related to the past and future of the universe: the Scale factor, which is a function of time. With reference to a graph whose coordinates are the Scale factor and time, the problem of dark matter is addressed again. Cosmological redshifts are measured to determine the scale of the universe. The discovery of the repulsive, anti-gravitational force of dark energy is explained. The lecture concludes with discussion of Einstein's biggest mistake: the invention of the cosmological constant to balance gravity.

1. Introduction
2. Planetary Orbits
3. Our Solar System and the Pluto Problem
4. Discovering Exoplanets: Hot Jupiters
5. Planetary Transits
6. Microlensing, Astrometry and Other Methods
7. Direct Imaging of Exoplanets
8. Introduction to Black Holes
9. Special and General Relativity
10. Tests of Relativity
11. Special and General Relativity (cont.)
12. Stellar Mass Black Holes
13. Stellar Mass Black Holes (cont.)
14. Pulsars
15. Supermassive Black Holes
16. Hubble's Law and the Big Bang
17. Hubble's Law and the Big Bang (cont.)
18. Hubble's Law and the Big Bang (cont.)
19. Omega and the End of the Universe
20. Omega and the End of the Universe
21. Dark Matter
22. Dark Energy and the Accelerating Universe and the Big Rip
23. Supernovae
24. Other Constraints: The Cosmic Microwave Background
25. The Multiverse and Theories of Everything

In this course, Yale Prof. Charles Bailyn focuses on three particularly interesting areas of astronomy that are advancing very rapidly: Extra-Solar Planets, Black Holes, and Dark Energy. Particular attention is paid to current projects that promise to improve our understanding significantly over the next few years. The course explores not just what is known, but what is currently not known, and how astronomers are going about trying to find out.



This Yale College course, taught on campus twice per week for 50 minutes, was recorded for Open Yale Courses in Spring 2007.