ASTR 1102 002 2008 Fall Semester Joel E Tohline Alumni Professor Office 247 Nicholson Hall Slides from Lecture22 Chapter 26 Cosmology and Chapter 27 Exploring the Universe The Hubble Constant H0 Let s examine more closely the meaning of the so called Hubble Constant H 0 H0 73 km s Mpc 73 km s 3 085 x 1019 km 2 37 x 10 18 s That is 1 H0 4 23 x 1017 s 13 4 billion yrs Interpretation of Hubble s Law Hubble s Law appears to put us in a special location in the Universe Everything appears to be expanding away from us Einstein s general theory of relativity provides a context for interpreting understanding Hubble s Law that does not put us in a special location 26 2 Universe is Expanding Natural solution to Einstein s general theory of relativity Motivated by the Hubble Law observations How to picture what s going on Expanding chocolate chip cake analogy Expanding balloon 26 2 Universe is Expanding Natural solution to Einstein s general theory of relativity Motivated by the Hubble Law observations How to picture what s going on Expanding chocolate chip cake analogy Expanding balloon analogy 26 6 Shape of the Universe Curvature Flat e g expanding cake analogy Positive curvature e g sphere balloon Negative curvature e g saddle shaped Critical density c 3H02 8 G Density parameter 0 0 c where 0 is the current average density of matter in the universe Circumference of circle 2 r Circumference of circle 2 r Circumference of circle 2 r 26 6 Shape of the Universe Curvature Flat e g expanding cake analogy Positive curvature e g sphere balloon Negative curvature e g saddle shaped Critical density c 3H02 8 G Density parameter 0 0 c where 0 is the current average density of matter in the universe How Do We Measure 0 Measure count up all the matter density in the universe 0 and compare the value to c Measure distances and redshifts of even more distant galaxies and look for deviations in the Hubble diagram How Do We Measure 0 Measure count up all the matter density in the universe 0 and compare the value to c Measure distances and redshifts of even more distant galaxies and look for deviations in the Hubble diagram How Do We Measure 0 Measure count up all the matter density in the universe 0 and compare the value to c Measure distances and redshifts of even more distant galaxies and look for deviations in the Hubble diagram Implications Big Bang About 13 4 billion years ago the universe must have been very dense hot and rapidly expanding Big Bang origin of the universe What are other implications of this model Specifically what were conditions like in the very early universe and can we test our predictions Implications of Big Bang Era of recombination and Cosmic Microwave Background CMB Origin of the Elements Non uniformities in the Early Universe and the Origin of Galaxies
View Full Document
Unlocking...