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) Now I have two questions about this solution to Einstein's equations: 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?