As has been mentioned elsewhere Halliwax mentions the Casimir effect in the Orchid video just before the 2nd #15 bunny arrives.

This is from Lostpedia on the Casimir Effect and Wormholes.

Exotic matter with negative energy density is required to stabilize a wormhole.[15] Morris, Thorne and Yurtsever[16] pointed out that the quantum mechanics of the Casimir effect can be used to produce a locally mass-negative region of space-time, and suggested that negative effect could be used to stabilize a wormhole to allow faster than light travel.