Do wormholes allow time travel?
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What hidden architecture of the universe would let information or people slip back through time without breaking causality as we know it?
Summary
The mainstream physics reading distinguishes mathematical possibility from physical feasibility. General relativity admits traversable-wormhole scenarios that could generate closed timelike curves, but known models face severe stability and energy-condition problems. Quantum effects, back reaction, or chronology protection may prevent a wormhole from becoming a usable time machine, and there is no evidence that wormholes exist.
- General relativity permits theoretical traversable-wormhole configurations that could produce closed timelike curves and hence past-directed travel.
- Keeping a wormhole traversable appears to require exotic matter or violations of the null-energy condition, with no known natural supply.
- Quantum and gravitational effects may destabilize the wormhole before a time machine can operate, supporting Hawking’s chronology-protection idea in studied models.
Deeper Insight
General relativity never ruled out a time machine. Give a wormhole two mouths that age differently, and one leads into the past.
Picture a tunnel through spacetime. Move one end fast, or park it near heavy gravity, and its clock falls behind the other. Step in one mouth, out the other, and you've gone back. The math works if you allow matter with negative energy, and the no-go results that should forbid it aren't conclusive. Some physicists even model multiple histories to dodge the paradoxes.
- What it could changeA stable wormhole would make causality something engineers could break, not just philosophers argue about.
- How it touches todayRing-wormhole models already let physicists study traversable shapes on paper, if exotic matter is allowed.
- Our futureThe past may be a place, not just a memory, if the universe allows the right shortcut.
- Some analyses argue that existing no-go results do not conclusively establish that all time machines are impossible.
- A traversable wormhole whose mouths experience different relativistic histories can, in theory, become a route to the past.
- Ring-wormhole models demonstrate that static, traversable geometries can be mathematically studied when negative-energy-condition matter is assumed.
Sources · 9
Featured · Primary source · arxiv.org
IINTRODUCTION
IINTRODUCTION ###### Abstract The recent interest in “time machines” has been largely fueled by the apparent ease with which such systems may be formed in general relativity, given relatively benign initial conditions such as the existence of traversable wormholes or of infinite cosmic strings. This
Read sourceAnalysis · scientificamerican.com
Can Time Travelers Reach the Past via Wormholes?
Can Time Travelers Reach the Past via Wormholes? | Scientific American December 1, 2015 Can Time Travelers Reach the Past via Wormholes? Astronauts already skip ahead in time, but the laws of physics seem to forbid going backward—or do they? By Tim Folger The famous writer H. G. Wells published his
Read sourceAnalysis · plato.stanford.edu
Time Machines (Stanford Encyclopedia of Philosophy)
Time Machines (Stanford Encyclopedia of Philosophy) # Time Machines First published Thu Nov 25, 2004; substantive revision Wed May 22, 2024 Recent years have seen a growing consensus in the philosophical community that the grandfather paradox and similar logical puzzles do not preclude the possibili
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