Structural Realism and Quantum Gravity

Tian Yu Cao

in The Structural Foundations of Quantum Gravity

Published in print November 2006 | ISBN: 9780199269693
Published online October 2011 | e-ISBN: 9780191699436 | DOI:
Structural Realism and Quantum Gravity

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Technically, it is very difficult to construct a tenable quantum theory of gravity. The major concern of a philosopher, however, is with having a consistent strategy to guide technical moves. If we look at quantum gravity this way, we immediately face a question of theoretical constraints imposed by general relativity and quantum field theory, which are the two most successful theories in fundamental physics: one deals with gravity in a classical field-theoretical framework, the other deals with quantum fields. Since quantum gravity means a quantum theory of the gravitational field, what should we do so that we can secure a chance of success if we cannot meet these constraints in their original forms, and thus have to go beyond the two theories? It was previously argued that the trouble is that it is impossible to meet the constraints imposed by these two theories in a single theory without radically revising each of them. Briefly, quantum field theory requires a Minkowskian spacetime as a fixed background, which is rejected by general relativity; and the latter requires a continuous manifold that cannot stand violent quantum fluctuations. What is the way out? Before any attempt is made to address this crucial issue, we have to take a closer look at the notions of physical reality offered by general relativity and quantum field theory respectively. This question is interesting in its own right, in addition to its relevance for our construction of a tenable quantum theory of gravity, because confusions in this regard have to be cleared before we can have a correct understanding of general relativity and quantum field theory. This chapter argues that structural realism is a framework in which the aforementioned confusions can be cleared and constraints met satisfactorily, and thus a strategy in guiding technical moves for constructing a consistent quantum theory of gravity can be suggested.

Keywords: structural realism; quantum field theory; quantum gravity

Chapter.  6978 words. 

Subjects: Philosophy of Science

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