Science › Space, time & gravity
Wormholes
1935· Idea
SpeculativeA serious idea with no experimental proof yet.
Hypothetical tunnels through spacetime connecting distant places, allowed on paper by general relativity but never observed.
See it on the Science map →How it works
Einstein and Nathan Rosen found a "bridge" linking two regions of spacetime in 1935; John Wheeler coined "wormhole" in 1957. Such tunnels would collapse instantly unless held open by exotic matter with negative energy, which is unknown in bulk. Kip Thorne and others showed in 1988 that a traversable wormhole, if it could exist, could also act as a time machine.
Why it matters
They test the limits of general relativity, and are central to speculative ideas linking gravity and quantum entanglement.
Think of it like
Like a tunnel connecting two floors of a building directly, skipping the stairs; legal on the floor plan, but no one knows a material that can hold it up.
How we know
None. They are mathematical solutions only. A 2022 quantum-computer experiment simulated a tiny wormhole-like model, but no real wormhole was created or observed.
Still a mystery
Whether nature allows the negative energy needed to keep one open, and whether quantum gravity forbids them, is unknown. Treat them as speculation.
Connections (6)
▸General relativity: gravity is curved spacetime permits on paper WormholesSpeculative
The relationship
Einstein's field equations accept many spacetime shapes as valid solutions, including tunnels joining two distant regions. The math does not say such shapes exist, only that they are allowed. Keeping a tunnel open long enough to pass through would require exotic matter with negative energy pushing outward; ordinary matter would make it pinch shut instantly.
How the link was found
Einstein and Nathan Rosen found the first such bridge in 1935. Michael Morris and Kip Thorne analyzed traversable wormholes in 1988.
Is it proven?
They are mathematically valid solutions, which is proven. Whether any exist in nature is not: there is no observation of a wormhole of any kind.
Open questions and mysteries
Whether enough negative energy can exist, and whether quantum gravity forbids wormholes outright, is unknown. Treat this link as speculation.
▸Wormholes would in theory allow Faster than light and time travelSpeculative
The relationship
A wormhole would be a shortcut: you would travel slower than light inside it, yet arrive somewhere faster than light could go the long way. Thorne's group showed that if one mouth were moved at high speed and brought back, time dilation would leave the two mouths at different times, making it a time machine.
How the link was found
Morris, Thorne and Yurtsever published the time-machine argument in 1988.
Is it proven?
Purely theoretical. The reasoning follows from accepted relativity, but it depends on wormholes existing, which has never been shown.
Open questions and mysteries
Hawking's 1992 "chronology protection" conjecture suggests quantum effects would destroy any such time machine as it formed. It is unproven.
▸Black holes joined in pairs would be WormholesSpeculative
The relationship
The complete mathematical version of Schwarzschild's solution includes a second universe-like region joined to ours by a throat, now called an Einstein–Rosen bridge. In principle, two black-hole mouths could be connected. But the throat pinches shut faster than anything, even light, could pass through. Real black holes formed from collapsing stars do not have the second side at all.
How the link was found
Einstein and Nathan Rosen described the bridge in 1935. Wheeler coined "wormhole" in 1957; Fuller and Wheeler showed in 1962 that it collapses too fast to cross.
Is it proven?
The bridge is exact math, but no wormhole has ever been observed. A traversable one would need "exotic" negative-energy matter (Morris and Thorne, 1988) never seen in bulk.
Open questions and mysteries
The 2013 "ER = EPR" idea suggests entangled particles might be joined by tiny wormholes. It is unproven but influential.
▸ER = EPR: entanglement may build space says entanglement equals tiny WormholesSpeculative
The relationship
The conjecture says the wormholes of general relativity and quantum entanglement are the same connection seen two ways. These are uncrossable wormholes: they collapse too fast for anything to pass through, just as entanglement links outcomes without carrying messages. Tweaks can briefly make them crossable, which corresponds to quantum teleportation.
How the link was found
Maldacena and Susskind, 2013. Ping Gao, Daniel Jafferis and Aron Wall showed in 2016 how a wormhole could briefly open, matching teleportation.
Is it proven?
Consistent in model universes. A 2022 Google quantum-computer study simulated a tiny toy wormhole; critics argued it does not show a real wormhole.
Open questions and mysteries
No wormhole has ever been observed in nature; whether crossable ones can exist is unknown.
▸John Wheeler gave the name to WormholesProven
The relationship
Einstein and Rosen had found in 1935 that general relativity allows bridges between distant regions of space. Wheeler studied such shortcuts as part of his vision of spacetime as dynamic and foamy, and gave them the name "wormhole," likening them to a worm boring through an apple.
How the link was found
Charles Misner and John Wheeler, in a 1957 paper.
Why it's proven
Wormholes are allowed solutions of Einstein's equations. None has been observed. Kip Thorne, Wheeler's student, showed in 1988 that crossable ones would need exotic negative energy.
Open questions and mysteries
Whether wormholes exist in nature, and whether they could ever be crossed, is unknown.
▸Albert Einstein with Rosen, first found WormholesSpeculative
The relationship
Einstein and Rosen were trying to describe particles as smooth features of spacetime rather than points. They found a solution where two sheets of spacetime join through a narrow throat, a bridge. They did not intend it as a travel route, and the bridge collapses too fast for anything to cross.
How the link was found
Albert Einstein and Nathan Rosen, in a 1935 paper in Physical Review; John Wheeler coined "wormhole" in 1957.
Is it proven?
The bridge is a valid mathematical solution of general relativity. Nothing like it has ever been observed.
Open questions and mysteries
In 2013 Maldacena and Susskind speculated that such bridges are linked to quantum entanglement, an untested idea called ER=EPR.