https://inspirehep.net/literature/394001malawi_glenn said:Evidence?
Any particular papers?
Here I present experimental evidence that the word "evidence" is also used in theoretical high energy physics:Vanadium 50 said:"Evidence" to me is something you get in a lab. I am not sure we have that here.
This seems amenable to reasonably straightforward theoretical analysis. I wonder if anyone's every written a paper on it.Demystifier said:Some evidence (Bekenstein, Hawking, Jacobson, Verlinde, ...) points to the idea that gravity is really a thermodynamic theory in disguise. Other evidence (Susskind, Maldacena, Witten, ...) points to the idea that gravity is dual to a lower dimensional conformal field theory (CFT). Are these two ideas mutually compatible? Can they both be true, and does it mean that some CFT's are really thermodynamic theories in disguise?
We investigate theories in which gravity arises as a consequence of entropy. We distinguish between two approaches to this idea: holographic gravity, in which Einstein's equation arises from keeping entropy stationary in equilibrium under variations of the geometry and quantum state of a small region, and thermodynamic gravity, in which Einstein's equation emerges as a local equation of state from constraints on the area of a dynamical lightsheet in a fixed spacetime background. Examining holographic gravity, we argue that its underlying assumptions can be justified in part using recent results on the form of the modular energy in quantum field theory. For thermodynamic gravity, on the other hand, we find that it is difficult to formulate a self-consistent definition of the entropy, which represents an obstacle for this approach. This investigation points the way forward in understanding the connections between gravity and entanglement.
The thermodynamics/gravity/CFT correspondence, often referred to as the AdS/CFT correspondence, is a theoretical framework that posits a relationship between a type of quantum field theory (Conformal Field Theory, or CFT) and a gravitational theory in a higher-dimensional space (typically Anti-de Sitter space, or AdS). This duality suggests that certain properties of black holes and other gravitational systems can be described by the thermodynamics of a lower-dimensional quantum field theory.
The AdS/CFT correspondence provides a way to understand the thermodynamics of black holes by mapping these gravitational systems to a conformal field theory. For example, the entropy of a black hole, which is proportional to its event horizon area, can be described by the entropy of the corresponding CFT. This correspondence helps in studying phenomena like Hawking radiation and black hole entropy from a quantum field theory perspective.
The holographic principle is a key concept in the AdS/CFT correspondence. It suggests that all the information contained within a volume of space can be represented as a theory on the boundary of that space. In the context of AdS/CFT, this means that a gravitational theory in a higher-dimensional AdS space can be described by a CFT on its lower-dimensional boundary, effectively "holographing" the higher-dimensional physics onto a lower-dimensional surface.
The AdS/CFT correspondence has applications across various fields of theoretical physics. It has provided insights into the behavior of strongly coupled quantum systems, such as quark-gluon plasma in quantum chromodynamics (QCD). It has also been used to study condensed matter systems, including superconductors and quantum phase transitions. Additionally, it offers a framework for exploring quantum gravity and the nature of spacetime.
While the AdS/CFT correspondence is a powerful theoretical tool, it has limitations and challenges. One major challenge is extending the correspondence to spaces that are not asymptotically AdS, such as our universe, which is better described by de Sitter space. Additionally, the correspondence is well-understood in specific cases, such as AdS5/CFT4, but generalizing it to other dimensions and more complex systems remains an ongoing area of research. Furthermore, the correspondence is primarily a theoretical construct, and experimental verification remains challenging.