Please give me some clues about the calculations for a non-rotating black hole

AI Thread Summary
The discussion centers on the dimensional consistency of calculations related to non-rotating black holes, specifically questioning whether the argument of the logarithm function should be adjusted from |r - r*| to |r/r* - 1|. Participants agree that using the latter form improves dimensional consistency. There is also a reference to Sean Carroll's notes on general relativity, which provide insights into Kruskal coordinates relevant to the calculations. The notes suggest parallels between Carroll's variables and those used in the original discussion. Overall, the conversation emphasizes the importance of dimensional analysis in black hole calculations.
park
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Homework Statement
non-rotating black holes
Relevant Equations
Kruskal coordinates
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The right-hand side doesn't look dimensionally consistent to me. Could it be that the argument of the ##ln## function should be something like ##|r/r^* - 1|## instead of ##|r - r^*|##?

It's a bit hard to check your work since you haven't indicated how ##p## and ##q## are defined.
 
oops! my mistake! p and q is defined ...
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i finally got a clue with your comment about dimensions!
For consistency of dimension, i think r-r* of (8.13) should be r/r*-1
 
park said:
i finally got a clue with your comment about dimensions!
For consistency of dimension, i think r-r* of (8.13) should be r/r*-1
Yes, things seem to work out better with the r/r*-1 form.

I'm not very familiar with Kruskal coordinates. Sean Carroll's notes on GR are freely available on the internet.
https://www.preposterousuniverse.com/grnotes/

He discusses Kruskal coordinates in this chapter:
https://preposterousuniverse.com/wp-content/uploads/grnotes-seven.pdf
The relevant material starts around page 182. Note equation (7.74) on page 186. I think his ##\tilde u## and ##\tilde v## are similar to your ##p## and ##q##, and his ##u'## and ##v'## are essentially your ##p'## and ##q'##. (But I believe Carroll is missing an overall negative sign in his expressions for ##v'## in (7.75) and (7.76). He corrects this in his published textbook.).
 
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