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ER = EPR: entanglement may build space
2013· Theory
SpeculativeA serious idea with no experimental proof yet.
A 2013 conjecture by Maldacena and Susskind that two entangled particles are connected by a tiny, uncrossable wormhole.
See it on the Science map →How it works
The name joins two 1935 papers, both co-written by Einstein and Nathan Rosen. ER is the Einstein-Rosen bridge, a wormhole linking two regions of space. EPR is the Einstein-Podolsky-Rosen paper on entanglement, the strong link between distant particles. The conjecture says these are the same thing. Two entangled black holes are joined by a real wormhole; for ordinary particles, the link is a 'quantum' wormhole with no ordinary shape. Neither can carry messages.
Why it matters
If true, entanglement is the glue that holds space together, and geometry and quantum information are two languages for one thing.
How we know
Supported in calculations within AdS/CFT models, building on Maldacena's 2001 work on paired black holes. A 2022 Google quantum-computer experiment simulated a toy wormhole; its meaning is disputed. No direct test exists.
Still a mystery
What a 'wormhole' between two single particles actually means geometrically is unclear, and whether the idea holds outside idealized models is unknown.
Connections (4)
▸Juan Maldacena proposed with Susskind ER = EPR: entanglement may build spaceSpeculative
The relationship
Maldacena had shown in 2001 that two black holes sharing a special entangled state are, in the gravity picture, the two mouths of one wormhole. In 2013 he and Susskind generalized: maybe all entanglement corresponds to some kind of wormhole connection, and all such wormholes to entanglement.
How the link was found
Juan Maldacena and Leonard Susskind, "Cool horizons for entangled black holes" (2013), building on Maldacena's 2001 eternal black hole paper and Mark Van Raamsdonk's 2010 work.
Is it proven?
It holds in AdS/CFT model calculations for black holes. The general claim is conjecture, without experimental test.
Open questions and mysteries
Whether it works for small systems like two electrons, where no clear geometry exists, is open.
▸Leonard Susskind proposed with Maldacena ER = EPR: entanglement may build spaceSpeculative
The relationship
Susskind brought the problem: the 2012 firewall paradox suggested black-hole complementarity might fail. ER = EPR offered an escape: radiation leaving a black hole stays connected to the interior through wormholes, so information is not duplicated and no firewall is needed. Susskind has since promoted it as a sign that quantum mechanics and gravity are one subject.
How the link was found
Leonard Susskind with Juan Maldacena, 2013, responding to the firewall paper by Almheiri, Marolf, Polchinski and Sully (2012).
Is it proven?
Mathematically consistent in models; not tested. Later Page-curve work (2019) fits its spirit.
Open questions and mysteries
Whether it fully resolves the firewall paradox is still debated.
▸ER = EPR: entanglement may build space ties wormholes to Quantum entanglementSpeculative
The relationship
ER = EPR claims entanglement has a geometric side. Two entangled black holes are linked by a real wormhole; for ordinary entangled particles, the link is a faint quantum version. This would explain why entanglement cannot send signals: the wormholes involved pinch off before anything can cross.
How the link was found
Juan Maldacena and Leonard Susskind, 2013, building on Einstein's 1935 papers on wormholes and on entanglement.
Is it proven?
Entanglement itself is proven, with a 2022 Nobel Prize for experiments. Its link to wormholes holds only in model calculations; untested.
Open questions and mysteries
If entanglement builds geometry, does every entangled pair in a lab share a tiny wormhole? No one knows how to test that.
▸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.