Investigated
Do wormholes allow time travel?
Short answer
Image: scientificamerican.com
In general relativity, a suitably traversable wormhole could in principle connect different times, especially if its mouths acquire a time offset. But no wormhole has been observed, and keeping one open appears to require exotic conditions while quantum and gravitational effects may prevent it from becoming a usable time machine. So wormholes make past-directed time travel mathematically conceivable, not technologically or physically established.
The views on this question
Two lenses on the same evidence. Source weight and the primary source ratio show what each rests on.
Alternative
Source weight 46%The dissenting theoretical position emphasizes that no decisive theorem rules out time machines. In carefully constructed general-relativistic models, a traversable wormhole can link regions with different temporal offsets and permit travel into the past. Some researchers explore self-consistency or multiple-history solutions to paradoxes, while acknowledging that these are speculative models rather than demonstrations of feasibility.
- 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.
- Models using multiple histories propose a way to resolve paradoxes produced by traversable-wormhole time machines, though this does not establish that such machines can exist.
Follow the white rabbit
Deeper threads worth pulling on next.
- How could a wormhole become a time machine?Different angle, same storyExplains mechanisms—moving a mouth or using gravitational time dilation—to create a time offset between wormhole mouths.
- What is exotic matter for wormholes?A different rabbit holeExplores the hypothetical negative-energy or exotic stress needed to keep a traversable wormhole open.
- Do quantum effects forbid time travel?Different angle, same storyCovers Hawking's chronology protection idea and semiclassical results suggesting quantum backreaction may prevent closed timelike curves.