{'fraction_non_alphanumeric': 0.028868360277136258, 'fraction_numerical': 0.025404157043879907, 'mean_word_length': 4.8979591836734695, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Casimir effect in a weak gravitational field: Schwinger’s approach

In this paper we discuss the Casimir effect in a small cavity at rest in the weak gravitational field of a massive, non-rotating source. We propose a new approach, based upon Schwinger’s effective action method, showing that the gravitational interaction induces a small correction in the vacuum energy density, in full agreement with the result we obtained in a previous work (Sorge 2005 Class. Quantum Grav. 22 5109), following a standard field mode decomposition technique. The present result reinforces the belief that gravity can indeed be effective in modifying the vacuum energy of a quantum field confined to the cavity, against the recent claim appeared in Lima et al (2019 J. Cosmol. Astropart. Phys. JCAP07(2019)11) that a weak gravitational field has no influence on the Casimir energy.