24.10.2012 Views

Chapter 6 Lecture: Principle of Equivalence

Chapter 6 Lecture: Principle of Equivalence

Chapter 6 Lecture: Principle of Equivalence

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

136 CHAPTER 6. LECTURE: PRINCIPLE OF EQUIVALENCE<br />

6.4.1 Total Redshift in a Gravitational Field<br />

Integrated redshift assuming relatively weak gravity<br />

� νs<br />

ν0<br />

ν0<br />

dν<br />

ν<br />

� s<br />

= −<br />

R<br />

GM<br />

r2 dr,<br />

c2 Exercise: Integrating, exponentiating both sides, and then expanding<br />

the right-side exponential (weak-field assumption) gives at radius s,<br />

νs<br />

≃ 1 − GM<br />

c2 � �<br />

1 1<br />

− .<br />

R s<br />

For a distant observer s → ∞ and (since the field is assumed weak)<br />

ν∞<br />

≃ 1−<br />

ν0<br />

GM<br />

Rc2 −→<br />

�<br />

ν0<br />

= 1 −<br />

ν∞<br />

GM<br />

Rc2 �−1 ≃ 1+<br />

� �� �<br />

Expand<br />

GM<br />

Rc2 (GM

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!