We’re Having a Field Day!

2019 ◽  
pp. 18-26
Author(s):  
Nicholas Mee

Space is permeated by fields, such as the electromagnetic field, that transmit forces between objects that are not in direct contact. This idea was first devised by Michael Faraday and its mathematical realization for the electromagnetic field was achieved by James Clerk Maxwell. Light is an electromagnetic wave that ripples through the electromagnetic field. Richard Feynman invented a diagrammatic representation of the interactions between particles that plays an important role in quantum field theory. Maxwell’s theory was the inspiration for Einstein when developing his new theory of gravity. Newton was criticized for suggesting the gravitational force acts between bodies that are not in contact. Einstein resolved this issue when he devised general relativity which is a gravitational field theory.

In this contribution, my purpose is to study a new mathematical instrument introduced by me in 1958-9: the tensor and spinor propagators. These propagators are extensions of the scalar propagator of Jordan-Pauli which plays an important part in quantum-field theory. It is possible to construct, with these propagators, commutators and anticommutators for the various free fields, in the framework of general relativity theory (see Lichnerowicz 1959 a, b, c , 1960, 1961 a, b, c ; and for an independent introduction of propagators DeWitt & Brehme 1960).


Entropy ◽  
2019 ◽  
Vol 21 (9) ◽  
pp. 844
Author(s):  
Ben Maybee ◽  
Daniel Hodgson ◽  
Almut Beige ◽  
Robert Purdy

Recently, Bennett et al. (Eur. J. Phys. 37:014001, 2016) presented a physically-motivated and explicitly gauge-independent scheme for the quantisation of the electromagnetic field in flat Minkowski space. In this paper we generalise this field quantisation scheme to curved spacetimes. Working within the standard assumptions of quantum field theory and only postulating the physicality of the photon, we derive the Hamiltonian, H ^ , and the electric and magnetic field observables, E ^ and B ^ , respectively, without having to invoke a specific gauge. As an example, we quantise the electromagnetic field in the spacetime of an accelerated Minkowski observer, Rindler space, and demonstrate consistency with other field quantisation schemes by reproducing the Unruh effect.


An investigation is started into a possible mathematical structure of the Wheeler-DeWitt superspace quantization of general relativity. The emphasis is placed throughout on quantum field theory aspects of the problem and topics discussed include canonical commutation relations in a triad basis, the status of the constraint equation and the rôle played by perturbation theory.


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