He suggests it is likely that traversable wormholes do not exist in nature.

“So according to our current best understanding, it seems likely that white holes, traversable wormholes, and these parallel universes don't exist, but we also used to think that black holes didn't exist.”

Current scientific understanding suggests that keeping a wormhole open requires a negative gravity substance which is currently hypothetical.

“we currently know of no way to in a sustained form keep a wormhole open preventing it from collapsing right because we need a negative gravity substance to pull the fabric of space apart right and all everything we know that substance does is pull it together with the force of gravity”

A wormhole can be held open by placing exotic matter with negative energy density within its throat, which produces a gravitational repulsion that counteracts the tendency to collapse.

“if you had what I like to call exotic matter that repels gravitationally and you put it inside the throat of a wormhole that can hold the Wormhole open”

Most physicists believe that stable, macroscopic wormholes do not exist and therefore cannot be used to build time machines.

“most physicists would say okay we think the laws of nature will be such that there aren't stable macroscopic big wormholes and that's what I think most physicists would say”

Wormholes are a leading theoretical proposal for achieving time travel to the past.

“So if you wanna travel to the past there are a few proposals that are on the market. But I'd say the one that has attracted the greatest attention is to make use of wormholes.”

He believes traversable wormholes are likely impossible because they require exotic matter that violates known physical laws.

“This exotic kind of matter, is really against the loss of physics, so it's, I have the prejudice that it will not exist. I'm bothered by the fact that we say that the science fiction wormholes are mathematically possible.”