[dbingham]

Wormholes are another. There's some debate whether or not the idea of creatable wormholes really exists in our physical models. But the idea of existing shortcuts through space time certainly does.

[gnaritas]

Wormholes aren't known to exist; they're theoretical implications of some math, not known things. It's entirely possible they don't exist at all.

[dbingham]

Hence the "in our models".