In six Level 1 videos we visualize General Relativity with a substratum (“fabric”) that uses the same *math* as GR, the math of curved surfaces.

Here in part 5 of 6: Wormholes are shortcuts through otherwise flat space. They can also act as time machines, if their mouths are properly attached to flat spacetime.

Classical wormholes need a material to keep them open whose property is such that it could be used to violate the conservation of energy

Can. J. Phys., 70,l 458, 1992

Indeed. For this reason, and the requirement of topological change, I suspect that wormholes will never be created.

That should have read

Can. J. Phys., 70, 458, 1992