Fuzzballs and the information paradox: a summary and conjectures (0810.4525v1)

Abstract: The black hole information paradox is one of the most important issues in theoretical physics. We review some recent progress using string theory in understanding the nature of black hole microstates. For all cases where these microstates have been constructed, one finds that they are horizon sized fuzzballs'. Most computations are for extremal states, but recently one has been able to study a special family of non-extremal microstates, and seeinformation carrying radiation' emerge from these gravity solutions. We discuss how the fuzzball picture can resolve the information paradox. We use the nature of fuzzball states to make some conjectures on the dynamical aspects of black holes, observing that the large phase space of fuzzball solutions can make the black hole more `quantum' than assumed in traditional treatments.

• The paper demonstrates that black hole microstates can be modeled as fuzzballs, offering a novel resolution to the information paradox.
• It uses string theory to construct horizon-sized structures that replace classical singularities and preserve quantum details.
• The study reveals an expanded phase space for black hole states, providing actionable insights into quantum gravity and black hole dynamics.

Fuzzballs and the Information Paradox: A Summary and Conjectures

The paper "Fuzzballs and the Information Paradox: a summary and conjectures" by Samir D. Mathur explores the complexities of the black hole information paradox, utilizing string theory to offer potential solutions. The paradox, a fundamental issue in theoretical physics, questions the fate of information that falls into a black hole, traditionally thought to be lost, contradicting the unitarity of quantum mechanics. The author reviews recent developments suggesting that black hole microstates can be understood as "fuzzballs," which in many constructed cases appear as horizon-sized structures without traditional horizons.

Fuzzball Theory

In string theory, black holes are not viewed as empty voids with singularity endpoints but rather as highly complex "fuzzballs" composed of microstates, each carrying detailed information. This approach challenges the conventional wisdom that quantum effects vanish at scales significant only at microscopic distances such as the Planck length. Instead, the fuzzball model posits that these effects extend over distances comparable to the black hole's horizon, providing a viable resolution to the paradox by circumventing the traditional assumptions.

Key Insights into Fuzzball Microstates

1. Structure of Microstates: The paper elaborates on the construction of black hole microstates using string theory, resulting in fuzzballs. These constructions demonstrate that microstates are not confined to a classical view of singularity and horizon but rather spread across the horizon area as "quantum fuzz."
2. Non-traditional Horizon: The absence of a classical, information-free horizon in these states suggests that all information could, in principle, be retrieved, aligning with quantum mechanics' unitarity.
3. Expanding Phase Space: The diversity and multiplicity of these fuzzball solutions suggest a vast phase space, which can make black holes inherently more "quantum" than previously assumed in standard treatments.

Implications on Black Hole Dynamics

The fuzzball paradigm encourages reconsideration of black holes' dynamics and information dissemination processes, impacting both theoretical and observational aspects. For instance, researchers must contemplate the implications of such structures for black hole radiation and interior evolution dynamics.

Conjectures on Black Hole Dynamics

The paper proposes speculative yet intriguing conjectures regarding fuzzball interactions and the implications for future developments in theoretical physics:

• Black Hole Evolution: The author suggests that the transition from a forming black hole to a fuzzball state could involve quantum mechanical tunneling into microstate configurations, contrary to solely classical gravitational collapse.
• Energy and Time Scales: It is proposed that fuzzballs challenge traditional notions by providing distinct energy and time scales that could offer different observational perspectives for infalling observers versus distant ones.
• Cosmological Implications: Mathur speculates on potential insights into the early Universe's state by considering fuzzball-like structures, suggesting a reevaluation of the "horizon problem" with nonlocal quantum states.

Challenges and Future Directions

Even though fuzzballs provide solutions to the paradox, much remains to be understood about their complete structure, taking into account all possible microstate solutions for non-extremal and extremal black holes. Additionally, for quantum gravity theories like string theory to offer comprehensive solutions to phenomena such as black hole entropy and cosmological constants, researchers will need to explore deeply how these structures integrate with existing physical laws along with novel predictive capabilities.

In conclusion, the fuzzball paradigm represents a significant theoretical shift with profound implications for black hole physics. The paper emphasizes ongoing challenges in fully realizing this theory but accentuates its potential in uniting aspects of quantum mechanics and general relativity, paving the way for resolving longstanding astronomical puzzles.