Black holes and wormholes in general relativity
Pro Research Analysisby 
Searched over 200M research papers
Black Holes in General Relativity: Properties and Regular Solutions
Black holes are fundamental solutions in general relativity, typically characterized by event horizons and central singularities. However, research has shown that it is possible to construct "regular" black holes—solutions that avoid singularities—by introducing nonlinear electrodynamics or scalar fields. For example, spherically symmetric black holes supported by nonlinear electromagnetic fields can be regular, especially in the case of pure magnetic charge, while dyonic (both electric and magnetic) solutions are more complex and may still have singularities unless specific conditions are met 124. Some models use scalar fields with "trapped ghost" properties, which are phantom in strong-field regions and canonical elsewhere, to achieve regular black hole solutions . These regular black holes can mimic the properties of classical black holes but avoid the problematic singularity at the center .
Wormholes in General Relativity: Traversability and Exotic Matter
Wormholes are hypothetical tunnels connecting distant regions of spacetime. In general relativity, traversable wormholes require "exotic matter"—matter that violates standard energy conditions, such as negative energy density or tension greater than the pressure at the center of a neutron star . Classic solutions show that traversable wormholes must have a throat with no event horizon, making them, in principle, passable by humans or signals . However, constructing such wormholes within general relativity is challenging due to the need for exotic matter.
Black Hole Mimickers and Wormhole Construction
Some models attempt to "mimic" black holes using regular spacetimes or wormholes. These mimickers can be constructed by modifying the mass distribution or using the "cut-and-paste" technique to join two regular black hole spacetimes, resulting in a wormhole with a dynamic throat . Stability analyses show that these wormholes can be stable under certain conditions, but their physical realization remains speculative .
Quantum Gravity, Entanglement, and Wormholes
Recent theoretical work suggests a deep connection between quantum entanglement and wormholes. The ER=EPR conjecture proposes that two entangled particles are connected by a nontraversable wormhole (Einstein-Rosen bridge). Concrete models show that entangled fermions can be described by static wormhole solutions in general relativity, and when evolved, these systems form black holes connected by a shrinking, nontraversable wormhole throat . This provides a possible explanation for the nonlocal correlations observed in quantum entanglement . Additionally, the microscopic origin of black hole entropy may be related to the existence of many microstates with geometric interiors containing Einstein-Rosen bridges, interpreted as quantum superpositions of wormholes .
Extensions Beyond Classical General Relativity
Modified gravity theories, such as higher-order curvature models and $f(Q)$ gravity, offer new possibilities for black hole and wormhole solutions. These extensions can introduce additional parameters and allow for solutions that may avoid singularities or require less exotic matter 57910. For example, some higher-curvature theories permit the construction of wormholes without any matter at all, relying solely on strong curvature effects to maintain the wormhole throat . However, in many cases, quantum corrections to general relativity still result in black holes rather than traversable wormholes, and singularity resolution is not always achieved .
Conclusion
In summary, general relativity allows for a rich variety of black hole and wormhole solutions, but traversable wormholes require exotic matter, and regular black holes often need modifications to the standard theory or the inclusion of nonlinear fields. Quantum gravity and modified gravity theories expand the landscape of possible solutions, offering new insights into the connections between black holes, wormholes, and the fundamental nature of spacetime. The interplay between entanglement and wormholes, as well as the search for singularity-free solutions, remains an active and exciting area of research 1234+6 MORE.
Sources and full results
Most relevant research papers on this topic