Viewpoint Wiki - All Viewpoints, No Gatekeepers

The emergent gravity viewpoint posits that quantum gravity may arise from more fundamental principles rather than requiring a separate, foundational theory. This perspective is advanced by some theoretical physicists seeking alternatives to dominant frameworks like string theory or loop quantum gravity. Proponents contend that gravity need not be treated as an independent force but could instead emerge from entanglement, thermodynamic effects, or other deeper mechanisms. The viewpoint represents a significant research direction in theoretical physics, particularly in efforts to reconcile general relativity with quantum mechanics. Advocates argue that if gravity is emergent, the challenges of quantizing it directly might be circumvented, offering a pathway to resolving long-standing paradoxes.

Advocates of emergent gravity contend that gravity does not require quantization as an independent entity but instead emerges from more fundamental physical laws. One key argument is that gravitational phenomena can arise from entanglement or thermodynamic effects, as suggested by the AdS/CFT correspondence and related holographic principles. For example, Ted Jacobson's work demonstrates how the Einstein field equations of general relativity can be derived from thermodynamic considerations, implying gravity might be a macroscopic manifestation of underlying microscopic dynamics.

Early insights into emergent gravity can trace back to Ted Jacobson's 1995 work, which demonstrated a thermodynamic derivation of Einstein's equations. This laid groundwork for viewing gravity as an emergent phenomenon rather than a fundamental force. The subsequent discovery of the AdS/CFT correspondence by Juan Maldacena in 1997 further reinforced this idea, showing how gravitational theories in anti-de Sitter space could be equivalent to conformal field theories without gravity. Erik Verlinde's 2010 entropic gravity proposal extended these ideas by suggesting that Newtonian gravity might emerge from entropy considerations in quantum systems.

While proponents generally agree on the emergent nature of gravity, debates persist regarding the completeness of this framework. Some argue that emergence alone may not fully account for quantum gravitational effects at high energies, suggesting additional mechanisms or principles might be required. Others explore whether spacetime discreteness is necessary or if a continuum description suffices within an emergent picture.

Another core argument is that emergence could resolve the black hole information paradox without necessitating a separate quantum gravity theory. Holography, in particular, provides a mechanism whereby information preserved in a black hole's event horizon might be encoded on its surface, aligning with quantum mechanical principles. Additionally, proponents highlight the mathematical consistency between general relativity and quantum field theory at low energies, suggesting that emergence could explain their apparent compatibility.

Ted Jacobson is a key figure in the emergent gravity framework, particularly for his thermodynamic interpretation of general relativity. Erik Verlinde has advanced the entropic gravity hypothesis, arguing that gravitational force arises from changes in the information content of spacetime. Leonard Susskind, an advocate of the holographic principle, has contributed to understanding how quantum mechanics and gravity might coexist through emergent mechanisms. Juan Maldacena's AdS/CFT conjecture remains a cornerstone of emergent gravity research, demonstrating deep connections between gravitational and non-gravitational theories.

- Quantum Gravity - string-theory-viewpoint - loop-quantum-gravity-viewpoint - Quantum Gravity - History - Quantum Gravity - Debate - quantum-gravity-consensus

1. Ted Jacobson, “Thermodynamics of Spacetime: The Einstein Equation of State,” Physical Review Letters 75, no. 26 (1995): 1260-1263. 2. Juan Maldacena, “The Large N Limit of Superconformal Field Theories and Supergravity,” Advances in Theoretical and Mathematical Physics 2 (1998): 231-252, arXiv:hep-th/9711200. 3. Erik Verlinde, “On the Origin of Gravity and the Laws of Newton,” Journal of High Energy Physics 2011, no. 4 (2011): 029.