NATS 1740 Lecture Notes - Lecture 20: Electronvolt, Scientific American, Wilkinson Microwave Anisotropy Probe

• School: York University
• Department: Natural Science
• Course: NATS 1740
• Professor: Radu Campeanu

Document Summary

Lecture 20 - the fate of our universe. What are the two possible scientific answers to the question how was the universe created ? . Explain how matter appeared in the universe. How do you answer the question how many universes are there ? . Two forces at work: the big bang expansion and the gravitational attraction of the galaxies. The cepheid variable stars are aged stars are known to brighten and dim regularly in a way which reveals their instrinsic brightness and implicitly their distances. Cepheid stars are visible only at relatively small distances (best bellow 80 million light- years). Provide a more powerful phenomenon which has a brightness independent of the galactic size. They occur in binary star systems approaching their end of life. If one star reaches the white dwarf stage and the other the red giant stage, the white dwarf will pull material to grow its size. When it reaches 1. 4 solar masses it explodes.