标题： 粒子在膨胀宇宙中的产生 显示英文标题

标题： The Creation of Particles in an Expanding Universe

摘要： 本文件是莱纳德·帕克的博士论文，于1966年提交给哈佛大学。 数十年来，几代物理学家都接触到了由引力场产生的粒子这一概念，这一现象已成为探索引力与量子理论相互作用的基石。 然而，导致这一现象的预测和理解的基础性突破仍为许多人所不熟悉。 为了历史准确性，并认可对物理学的重要贡献，该论文已被重新输入并作为开放获取（arXiv）文档免费提供。 再版的论文附有一篇序言，将其置于适当的历史背景中。 作为本次新版本的负责人，我们（安东尼奥·费雷罗、何塞·纳瓦罗-萨拉斯和西尔维娅·普拉）希望未来的世代能继续从这本开创性的著作中获得启发。 显示英文摘要

摘要： This document is the Ph.D. thesis of Leonard Parker, submitted to Harvard University in 1966. Over the decades, several generations of physicists have been introduced to the concept of particle creation by gravitational fields, a phenomenon that has become a cornerstone in exploring the interplay between gravitation and quantum theory. Yet, the foundational breakthrough that led to the prediction and understanding of this phenomenon remains unfamiliar to many. In the interest of historical accuracy and in recognition of a seminal contribution to physics, the thesis has been retyped and made it freely available as an open-access (arXiv) document. The reissued thesis is accompanied by a Foreword that places the work in its proper historical context. As the team responsible for this new edition, we (Antonio Ferreiro, Jos\'e Navarro-Salas, and Silvia Pla) hope that future generations will continue to draw inspiration from this pioneering text.