Interpenetrating subspaces as a funnel to extra space
  New solution for two interpenetrating universes is found. Higher derivative gravity acting in 6-dimensional space is the basis of the study that allows to obtain stable solution without introducing matter of any sort. Stability of the solution is maintained by a difference between asymptotic behavior at spacial infinities. For an external observer such a funnel looks similar to a spherical wormhole. 
Sergey G. Rubin
gr-qc astro-ph.CO hep-th