hw9 - J at the beginning of Chapter 2 useful, but you...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Physics 3002, Problem Set 9, due 4/15/09 Lam Hui 1. Ryden problem 7.7. In this problem, you are asked to show that the total physical area (measured today) of a sphere with a radius r (here, r refers to the coordinate radial distance, not a physical distance) is given by equation 7.24. You should be able to show this starting from the Robertson Walker metric given in equation 7.22. Note that in Ryden, d Ω 2 is a shorthand for 2 + ( sin θ ) 2 2 . 2. Ryden problem 7.8. Hints for the second part of this problem (i.e. deriva- tion of equation 7.54): 1. you might Fnd the discussion on intensity
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: J at the beginning of Chapter 2 useful, but you should also keep in mind that equation 2.2 for instance assumes Minkowski space, which is not what we have here; 2. the problem tells you that n is the number density of standard candles today, and that the candles are neither created nor destroyed as you go backward (or forward) in time you should think carefully what this means for the proper number density versus comoving number density (one stays constant but the other changes with time)....
View Full Document

This note was uploaded on 02/23/2010 for the course PHYS 3002 taught by Professor Lam during the Spring '10 term at Columbia.

Ask a homework question - tutors are online