The introduction clarifies why justice between generations should be approached in dialogue among different cultural-philosophical traditions, resulting in the unique crossing of two “inters” -- intercultural philosophy and intergenerational justice. In times of large-scale environmental destabilization, fairness between generations is an urgent issue of justice across time, but it is also a global issue of justice across geographical and nation-state borders. Thus, different philosophical cultures and traditions of thought from around the globe should converse to reflect on what is fair to future people. The introduction details these claims and gives an overview of the volume’s chapters.

This chapter engages with the world of ghosts and spirits (guishen 鬼神) in the classical Chinese tradition. While there has been agreement about the existence of ghosts, their status and the duties of currently living humans to them is all but clear. We argue that a Confucian innovation consists in acknowledging the existence of the spirit world in an “as if” mode. In this conception, humans share obligations of respect while they are well advised to practice attentive distancing to these beings. The mechanisms governing a haunted cosmos are ultimately beyond human comprehension. Ghosts are stand-ins and correctives who reveal the limits of human control and comprehension. We conclude by discussing the potential contributions of this Confucian conception of ghosts and spirits to contemporary debates on intergenerational justice.

Introduction

Quantum optics

The atom is the most elementary constituent of any model that describes the quantum nature of light–matter interaction. Because atoms emit and absorb light at well-defined frequencies, nineteenth century scientists thought of them as collections of harmonically oscillating electric dipole moments or EHDs. In the language of modern physics, the latter represent dipolar transitions among the various quantum mechanical states of an atom.

In a strict definition, the field of quantum optics deals with problems that not only require the quantization of matter but also of the electromagnetic field, with examples such as (i) generation of squeezed light or Fock states, (ii) strong coupling of an atom and a photon, (iii) entanglement of a photon with an atom and (iv) Casimir and van der Waals forces. There are also many other important topics that have been discussed within the quantum optics community but do not necessarily require a full quantum electrodynamic (QED) treatment. Examples are (i) cooling and trapping of atoms, (ii) precision spectroscopy and (iii) modification of spontaneous emission.

The simple picture of a TLS as an EHD remains very insightful and valuable to this day. Indeed, much of what we discuss in this chapter has to do with the interplay between the quantum and classical mechanical characters of dipolar oscillators. For instance, the extinction cross-section of a TLS, given by 3λ2/2π, can be derived just as well using quantum mechanics [70] or classical optics [234]. Another example, albeit more subtle, concerns the spontaneous emission rate.