# Homework Help: Cauchy Horizon

1. Apr 9, 2015

### latentcorpse

Hi there,

I have a metric with $$g_{rr}=\frac{1}{r^2-2cr}$$. From this it is clear there exist coordinate singularities at r=0 and r=2c.

I believe that the outer horizon is the event horizon and the inner horizon is a Cauchy horizon. However, I do not know what I need to do in order to prove that this is the case. Can anyone offer any advice?

One option would be to try and draw a Penrose diagram. However, this usually involves lots of horrible coordinate transformations (even for the simplest examples) and my full metric is pretty complicated so if there's an alternative, I'd prefer that!

Thanks.

2. Apr 14, 2015