Can you say that if the classical limit of LQG is still unknown? For string theory I'm pretty sure that it's not Machian as it reproduces GR plus stringy corrections and allows for the Minkowski vacuum, but for LQG I'm not sure.Demystifier said:LQG is based on GR, and GR is not a Machian theory, so LQG is not a Machian theory.
It is believed that classical limit of LQG is GR, but there is no rigorous proof. If one day someone proves the opposite, namely that certain precise formulation of LQG does not have GR as its classical limit, then this particular formulation of LQG will be abandoned and a different version of LQG will be called "the" LQG.haushofer said:Can you say that if the classical limit of LQG is still unknown?
Demystifier said:It is believed that classical limit of LQG is GR
I think this question is only relevant at points at which fermions are present:tzimie said:GR or Cartan-GR?
Machian theory, also known as Mach's principle, is a concept in physics proposed by Ernst Mach. It suggests that the inertia of an object is determined by the presence of all other objects in the universe. In other words, the motion of an object is not only affected by the forces acting upon it, but also by the distribution of matter in the entire universe.
Loop Quantum Gravity (LQG) is a theory that attempts to reconcile general relativity and quantum mechanics. It is often considered to be a Machian theory because it incorporates the concept of relationalism, which states that the properties of space and time are relative to the objects within it. LQG also suggests that the fabric of space-time is made up of discrete units, similar to how matter is quantized in quantum mechanics.
There is currently no direct evidence that supports the idea of LQG being a Machian theory. However, some physicists believe that LQG provides a more relational approach to space and time, which aligns with Mach's principle. Additionally, LQG has been successful in predicting certain phenomena, such as the black hole entropy, which suggests that it could be a promising theory for understanding the nature of space and time.
Yes, there are some criticisms of LQG as a Machian theory. Some argue that LQG is not truly relational, as it still relies on a fixed background space-time. Others point out that LQG has yet to be fully developed and needs more empirical support before it can be considered a complete theory. Additionally, some physicists argue that Mach's principle is not a testable concept, making it difficult to determine whether LQG truly aligns with it.
The concept of Mach's principle challenges the traditional notion of space and time being absolute, and instead suggests that they are relative to the objects within it. This has significant implications for our understanding of the universe, as it forces us to reconsider our ideas about the nature of space and time. It also raises questions about the role of observers in shaping our understanding of the universe and the interplay between matter and space-time.