NATS 1740 Lecture Notes - Lecture 3: Cosmic Calendar, Dark Matter, Local Group

• School: York University
• Department: Natural Science
• Course: NATS 1740
• Professor: Michael De Robertis, Alireza Rafiee

Document Summary

Compare out lifetimes to the age of the universe: how did we come to be, birth of the universe. => expansion (not an explosion, not a bomb): big bang => the space between galaxies expanded and pushed everything out: galaxies as cosmic recycling plants. 2 elements made of the universe: hydrogen and helium. The carbon, oxygen, anything heavier than helium came from star => through lifetime reduce more heavier elements: life cycle of stars. Little parts from clouds of gas and dust => stars shine with energy released from nuclear fusion (elements heavier than helium) => massive stars explode when they die. Stars form with the variety of mass. Heavier, bigger the star => the shorter the lifetime. => tiny stars live longer: earth and life. We and our planet are made from elements manufactured in stars that lived and died long ago. The cosmic calendar: a scale we compress the time (history) of universe into 1 year.