A Kantian account of mathematical modelling and the rationality of scientific theory change: The role of the equivalence principle in the development of general relativity

2018 ◽  
Vol 71 ◽  
pp. 45-57
Author(s):  
Jonathan Everett
2021 ◽  
Author(s):  
James F. Woodward

“Breakthrough” advanced propulsion can only take place with a correct understanding of the role of inertia in general relativity. Einstein was convinced that inertia and gravitation were the obverse and reverse of the coin. The most general statement of the principle of relativity, captured in his Equivalence Principle and the gravitational induction of inertia. His ideas and how they have fared are reprised. A rest mass fluctuation that is expected when inertia is gravitationally induced is then mentioned that can be used for propulsion. Recent work supported by National Innovative Advanced Concepts Phase 1 and 2 NASA grants to determine whether thrusters based on gravitationally induced inertia can actually be made to work is presented. A recent design innovation has dramatically increased the thrust produced by these Mach Effect Gravity Assist (MEGA) impulse engines.


2016 ◽  
Vol 13 (08) ◽  
pp. 1640007 ◽  
Author(s):  
Salvatore Capozziello ◽  
Mariafelicia De Laurentis

Fundamental issues underlying gravitational physics and some of the shortcomings of Einstein’s general relativity (GR) are discussed. In particular, after taking into account the role of the two main objects of relativistic theories of gravity, i.e. the metric and the connection fields, we consider the possibility that they are not trivially related so that the geodesic structure and the causal structure of the spacetime could be disentangled, as supposed in the Palatini formulation of gravity. In this perspective, the equivalence principle (EP), in its weak and strong formulations, can play a fundamental role in discriminating among competing theories. The possibility of its violation at quantum level could open new perspectives in gravitational physics and in unification with other interactions. We shortly debate the possibility of EP measurements by ground-based and space experiments.


2021 ◽  
pp. 11-26
Author(s):  
Andrew M. Steane

This chapter is a survey of central ideas and equations in general relativity. The basic equations are written down with a view to seeing where we are heading in the book, and in order to present both the field theory and the geometric interpretation of gravity. The central role of the metric is introduced, and the equivalence principle is discussed. It is emphasized that spacetime interval is both a mathematical and a physical idea. It is explained how gravity works “behind the scenes” by modifying equations which otherwise look like familiar equations of electromagnetism. The sense in which acceleration is in some respects a relative and in some respects an absolute concept is explained. It is shown why the motion of matter, not just its mass, must influence gravitation. The stress-energy tensor is introduced and defined.


2022 ◽  
Vol 19 (3) ◽  
pp. 5-32
Author(s):  
N. V. Golovko

The paper aims to show the importance of reasoning “from metaphysics” in the course of a consistent interpretation of the “against neoscholasticism” thesis (J. Ladyman). The idea that “the subject of metaphysics is metaphysical possibilities, and science determines which of them are actually achieved” (E. J. Lowe, J. Katz, etc.) reinforces the role of reasoning “from metaphysics” within the field of metaphysics of science. The general theory of relativity violates the common prevailing intuition that “causality is the subject of local physical interaction” (J. Bigelow). Interpretation of causality in terms of “forces” and “coming into” within the framework of E. J. Lowe's ontology makes it possible to talk about causality in terms of “finding” and “going out” of existence of the corresponding modes of objects connected by a formal “causal relationship”. The transition to E. J. Lowe's ontology helps not only to overcome the intuition of the locality of causality, but also reveals in its own way, for example, such seemingly simple common intuitions as the dependence of the truth of propositions on time or the understanding of time as a dimension. All this once again brings us back to the understanding of the importance of the fact that a scientist, constructing or interpreting a scientific theory, as a rule, uses non-trivial philosophical assumptions that should be the subject of its own philosophical analysis. 


Author(s):  
S.J. Matthew Carnes

The transformation of political science in recent decades opens the door for a new but so far poorly cultivated examination of the common good. Four significant “turns” characterize the modern study of politics and government. Each is rooted in the discipline’s increased emphasis on empirical rigor, with its attendant scientific theory-building, measurement, and hypothesis testing. Together, these new orientations allow political science to enrich our understanding of causality, our basic definitions of the common good, and our view of human nature and society. In particular, the chapter suggests that traditional descriptions of the common good in Catholic theology have been overly irenic and not sufficiently appreciative of the role of contention in daily life, on both a national and international scale.


Author(s):  
Steven French

What is a scientific theory? Is it a set of propositions? Or a family of models? Or is it some kind of abstract artefact? These options are examined in the context of a comparison between theories and artworks. On the one hand, theories are said to be like certain kinds of paintings, in that they play a representational role; on the other, they are compared to musical works, insofar as they can be multiply presented. I shall argue that such comparisons should be treated with care and that all of the above options face problems. Instead, I suggest, we should adopt a form of eliminativism towards theories, in the sense that a theory should not be regarded as any thing. Nevertheless, we can still talk about them and attribute certain qualities to them, where that talk is understood to be made true by certain practices. This shift to practices as truth-makers for theory talk then has certain implications for how we regard theories in the realism debate and in the context of the nature and role of representation in science.


Author(s):  
David M. Wittman

The equivalence principle is an important thinking tool to bootstrap our thinking from the inertial coordinate systems of special relativity to the more complex coordinate systems that must be used in the presence of gravity (general relativity). The equivalence principle posits that at a given event gravity accelerates everything equally, so gravity is equivalent to an accelerating coordinate system.This conjecture is well supported by precise experiments, so we explore the consequences in depth: gravity curves the trajectory of light as it does other projectiles; the effects of gravity disappear in a freely falling laboratory; and gravitymakes time runmore slowly in the basement than in the attic—a gravitational form of time dilation. We show how this is observable via gravitational redshift. Subsequent chapters will build on this to show how the spacetime metric varies with location.


2005 ◽  
Vol 6 (Suppl 3) ◽  
pp. S15
Author(s):  
Najl Valeyev ◽  
Andrei Skorinkin ◽  
Kristy Downing ◽  
Iain Campbell ◽  
Nikolai Kotov

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