# Questions about the traversable wormhole metric

1. Sep 24, 2014

### space-time

First of all, the metric I am referring to is this one:

ds2= -c2dt2 + dl2 + (k2 + l2)(dᶿ2 + sin2(ᶿ)dø2)

where k is the radius of the throat of the wormhole. (sorry for the small Greek letters)

1. What does the coordinate l represent? All I know is that its domain is all real numbers and negative values of l apparently represents another universe.

2. When this solution was derived, did the equations include the cosmological constant or was that just left out?

2. Sep 24, 2014

### bapowell

1. Looks like $l$ is the radial coordinate.

2. In order for this to be a solution to Einstein's Equations, you need exotic matter that violates the energy conditions. There might be a cosmological constant but its contribution is swamped by that of the exotic matter.