A Developments to unify quantum theory with General Relativity?

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mathman

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Have there been any recent developments in the attempt to unify the standard model of quantum theory with General Relativity? It appears the no progress has been made recently in string theory or loop quantum gravity.
 

MathematicalPhysicist

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As time passes by it seems to me that a sort of "incompleteness" in this unification scheme is in order.
Just awaits for Godel of Quantum Gravity to prove it... :oldbiggrin:
 

mathman

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I am somewhat more optimistic. Godel was dealing in mathematics. I doubt if you can "prove" incompleteness for physical theories.
 

MathematicalPhysicist

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I am somewhat more optimistic. Godel was dealing in mathematics. I doubt if you can "prove" incompleteness for physical theories.
What will make you a pessimist?
Well a physical theory is constructed with maths, so the mathematics will be incomplete, and the physics won't make sense anyway, it's either inconsistent or incomplete.
 

Nugatory

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Well a physical theory is constructed with maths, so the mathematics will be incomplete, and the physics won't make sense anyway, it's either inconsistent or incomplete.
This seems like a total non sequitur to me. How do you get from true but not provable propositions in an axiomatic system to propositions that “won’t make sense”?
 

MathematicalPhysicist

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This seems like a total non sequitur to me. How do you get from true but not provable propositions in an axiomatic system to propositions that “won’t make sense”?
Well "making sense" is with regards to classical logic.
It might make sense for someone using paraconsistent logic or some other non-conventional logic I am unaware of.
 
This seems like a total non sequitur to me. How do you get from true but not provable propositions in an axiomatic system to propositions that “won’t make sense”?
Godel does not have "true but not provable" propositions. It has unprovable propositions that become axioms as you extend the maths. The axioms are neither true not false. You can accept them as true, or you can accept various negations of them as true. E.g. the unprovable generalized continuum hypothesis may be accepted or rejected according to taste.

 
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Demystifier

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I am somewhat more optimistic. Godel was dealing in mathematics. I doubt if you can "prove" incompleteness for physical theories.
It could be something like the Bell theorem for local hidden variables in quantum mechanics. The theorem might state that no theory can simultaneously have properties of being (i) quantum, (ii) general covariant and (iii) obeying some additional property that currently everybody takes for granted.
 

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