Mach’s Principle and the Origin of Inertia

Abstract

The current status of Mach's principle is discussed within the context of general relativity. The inertial properties of a particle are determined by its mass and spin, since these characterize the irreducible unitary representations of the inhomogeneous Lorentz group. The origin of the inertia of mass and intrinsic spin are discussed and the inertia of intrinsic spin is studied via the coupling of intrinsic spin with rotation.The implications of spin-rotation coupling and the possibility of history dependence and nonlocality in relativistic physics are briefly mentioned.

Gravitomagnetic Stern–Gerlach Force

“…Spin-rotation coupling has extensive observational support [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. It has recently been observed directly in neutron interferometry [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ]. Furthermore, it has significant applications in spintronics [ 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ].…”

Review of the Gravitomagnetic Clock Effect

“…Indeed, inertial effects are not of gravitational origin; instead, the gravitational field of external masses would generate gravitational tidal effects in the laboratory. [5,[81][82][83] We have adopted Einstein's interpretation of Mach's ideas regarding inertia; however, there has been a diversity of opinion in connection with Mach's views. As a matter of fact, Mach's profound and intriguing ideas have been explored by a number of authors; see, for instance.…”

“…On the other hand, the inertial properties of intrinsic spin have been the subject of recent investigations. [83,[91][92][93][94] The inertia of intrinsic spin, which is completely independent of the inertial mass, elevates the issue of the origin of inertia to the quantum domain. Regarding GTR, mass-energy is essential in generating classical gravitational fields, while intrinsic spin couples to the gravitomagnetic field of a rotating source.…”