Inside black holes
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Exploring the Interior of Black Holes
Volume Inside Black Holes
The volume inside black holes is a topic of significant interest in modern physics. Contrary to the common perception that black holes are small due to their tiny exterior area, the interior volume can be surprisingly large. Research has shown that the horizon of a black hole bounds large spacelike hypersurfaces. This volume can be defined using maximal surfaces, and it has been found that in an evaporating black hole, the volume of these surfaces grows monotonically with advanced time, even as the exterior area shrinks1. This finding has implications for the information paradox and remnant scenarios, suggesting that the interior volume of black holes could play a crucial role in these phenomena1 4.
Stable Orbits and Potential for Life
Inside rotating or charged black holes, there exist stable periodic orbits for both particles and photons. These orbits, classified as orbits of the third kind, do not terminate at the central singularity nor escape the black hole. The existence of such orbits implies that there could be regions within supermassive black holes where life might theoretically exist, shielded from the outside universe2. This intriguing possibility opens up discussions about civilizations potentially inhabiting the interiors of supermassive black holes in galactic nuclei2.
Geometric Interpretation and Time Dependence
The three-dimensional volume inside a spherical black hole can be defined by extending an intrinsic flat-spacetime characterization of the volume inside a two-sphere. This volume grows with time since the collapse of the black hole, reaching a simple asymptotic form that has a compelling geometrical interpretation4. The volume inside a black hole is also dependent on the definition of time and can vary or even be zero depending on the chosen time-coordinate definitions5. These findings provide a new pedagogical resource for understanding the complex geometry of black holes.
Probing the Interior from Outside
The cosmic censorship conjecture suggests that singularities within black holes are hidden by an event horizon, making them unobservable from the outside. However, quantum analogues of this problem indicate that it might be possible to probe the structure of the singularity from outside the horizon. For instance, the transition rates of an Unruh–DeWitt detector placed outside the horizon of an eternal BTZ black hole differ from those of its geon counterpart, implying that the internal structure can influence external observations7. This suggests that astronomical tests of black hole surroundings could provide valuable information about their interiors9.
Conclusion
The interior of black holes is a rich and complex subject, with significant implications for our understanding of the universe. From the surprising volume inside black holes to the potential for stable orbits and even life, the study of black hole interiors challenges our perceptions and opens up new avenues for research. The ability to probe these interiors from the outside further enhances our understanding, suggesting that black holes are not just isolated objects but are deeply connected to the fabric of the cosmos.
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Most relevant research papers on this topic
Volume inside old black holes
The volume of maximal surfaces inside an evaporating black hole grows monotonically with advanced time, while the area shrinks, potentially impacting the information paradox and remnant scenarios.
Is there life inside black holes?
There is potential for life inside supermassive black holes, with stable planetary orbits and the Chandrasekhar classification suggesting that life may exist in their interiors.
Black Holes
Black holes play a crucial role in powering quasars and providing insights into quantum gravity, with recent developments involving cosmic censorship and the statistical origin of black hole entropy.
Highly CitedHow big is a black hole
A black hole's three-dimensional volume is large, potentially impacting the information paradox discussion.
Highly CitedThe volume inside a black hole
The three-dimensional spatial volume inside a black hole depends on the definition of time, and can even be time-dependent or zero, while the surface area remains the same for all observers.
Looking inside a black hole
We can probe the structure of a black hole's singularity from outside its event horizon, despite its event horizon being hidden by a cosmic censorship conjecture.
Interior of Distorted Black Holes
Distorted black holes have a general interior solution and asymptotics near the horizon and singularity, with special results for 'caged' black holes.
Hearts of Darkness: the inside out probing of black holes
Astronomical tests of black hole surroundings can provide valuable information about their unexplored interiors, challenging the assumption that quantum gravity effects remain confined to black hole interiors.
Cool horizons for entangled black holes
Entangled black holes can resolve AMPS(S) paradoxes and potentially resolve firewall paradoxes in more general situations.
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