For a simplified notion of a wormhole, space can be visualized as a two-dimensional surface. In this case, a wormhole would appear as a hole in that surface, lead into a 3D tube (the inside surface of a cylinder), then re-emerge at another location on the 2D surface with a hole similar to the entrance.
If you ever happen to fall through a wormhole, you won't be coming back. It will snap shut behind you. But on the way, you may have just enough time to send one last message home.
Einstein's theory of general relativity mathematically predicts the existence of wormholes, but none have been discovered to date. A negative mass wormhole might be spotted by the way its gravity affects light that passes by.
No one has yet seen a wormhole, but theoretically they could provide shortcuts to distant parts of the universe, or to other universes entirely, if they exist (SN: 7/27/17).
Unless the wormhole was thoroughly cleaned out and everything else blocked from entering it, falling in would mean certain death. “Whenever you travel close to the speed of light, any particle or dust grain or anything that you hit will be problematic. Even a photon would cause you trouble,” says Maldacena.
Russian scientists at the Pulkovo Central Astronomical Observatory also think so. However, they note that the nearest such object is 13 million light-years away.
While researchers have never found a wormhole in our universe, scientists often see wormholes described in the solutions to important physics equations. Most prominently, the solutions to the equations behind Einstein's theory of space-time and general relativity include wormholes.
Wormholes are thought to be highly unstable, and the insertion of foreign matter might cause them to collapse completely. In theory, wormholes are tunnel-like connections made out of spacetime, offering a shorter distance between two vastly separated areas of the universe.
While most wormholes only last for 24 hours, there are some variations to this rule. When a static wormhole collapses a new one with the same properties will spawn somewhere else in the same system. It will have to be scanned down. When a non-static wormhole collapses it simply disappears forever.
The powerful gravity within a wormhole would be a problem in a few other ways, too. For one, anything else that fell into the wormhole – even a photon of light – would quickly get boosted to such high energies that if it hit you on your way through it would probably kill you immediately.
In reality, however, Einstein's theory of general relativity shows that it would not be possible for matter to actually cross these “tunnels through space”. But physicists are still considering whether that hypothesis is false: quantum effects could play a role in refuting this hypothesis.
However, according to general relativity, it would not be possible to use a wormhole to travel back to a time earlier than when the wormhole was first converted into a time "machine". Until this time it could not have been noticed or have been used.
If you were to find a wormhole and send a single bit of light - a single photon - down the tunnel, the reaction of that photon's energy to the space-time around it would be enough to completely destroy the wormhole faster than the speed of light.
While researchers have never found a wormhole in our universe, scientists often see wormholes described in the solutions to important physics equations. Most prominently, the solutions to the equations behind Einstein's theory of space-time and general relativity include wormholes.
Astronomers have discovered the closest black hole to Earth, the first unambiguous detection of a dormant stellar-mass black hole in the Milky Way. Its close proximity to Earth, a mere 1,600 light-years away, offers an intriguing target of study to advance understanding of the evolution of binary systems.
A spacecraft could theoretically skip ahead to a distant region of space if it enters such a wormhole between the two locations. As in our familiar universe, objects in a wormhole would have to travel slower than the speed of light, which, in a vacuum is 186,282 miles per second (299,792 kilometers per second).
Imagine space as a curved two-dimensional plane. Wormholes like this could form when two masses apply enough force on space-time to create a tunnel connecting distant points. Theoretical Kerr black holes aren't the only possible cosmic shortcut to the past or future.
Time travel to the past is theoretically possible in certain general relativity spacetime geometries that permit traveling faster than the speed of light, such as cosmic strings, traversable wormholes, and Alcubierre drives.
In astrophysics, spaghettification is the tidal effect caused by strong gravitational fields. When falling towards a black hole, for example, an object is stretched in the direction of the black hole (and compressed perpendicular to it as it falls).
Wormholes are allowed to exist in the math of "General Relativity", which is our best description of the Universe. Assuming that general relativity is correct, there may be wormholes. But no one has any idea how they would be created, and there is no evidence for anything like a wormhole in the observed Universe.