Space

...Exotic matter is a hypothetical form of matter theorized to contain unusual properties often characterized by a negative energy density, meaning it would have a negative mass or exert a repulsive gravitational force. Wormholes would require a shell of exotic matter, but just like wormholes, exotic matter has never been observed and is considered hypothetical.

“If you could somehow create that state of matter, then, according to general relativity, you could have a wormhole. But if you ask me whether that kind of matter is possible, I doubt it,”...

As of now, scientists don’t know enough about the characteristics of wormholes to confidently identify them, such as the types of situations that would create a wormhole, the properties of a wormhole, and how to detect said properties...

One key feature is that a wormhole would look like a sphere, not a hole, says Lupsasca, adding that to travel through a wormhole would be like “getting sucked into a ball and then expelled from another ball.”...

Imagine living in a two-dimensional world, like a sheet of paper. When that sheet of paper is folded over . . . these separate locations in “space-time” are joined together in much the same way a wormhole might do. Similarly, if a person were to go through a wormhole, it would change their location in both space and time.