  This is a brief history of photons, both soft and hard, real and virtual.
About 150-100 years ago, Maxwell and Einstein discovered intriguing properties
of electromagnetic fields and how to understand them both macroscopically and
microscopically. Decades later, physicists developed the theory of renormalized
quantum electrodynamics (QED), an incredibly accurate theory describing
interactions of photons and other particles. Photons are used everywhere in
academia and technological devices, from supermarket lasers and doors to
academic studies in atomic, nuclear, and particle physics. In this article, I
attempt to convey how the field of relativistic heavy ions rediscovered
ultra-peripheral collisions (UPC) as a source of intense, almost real photons,
and how it permits the study of a plethora of phenomena in the aforementioned
academic fields. These phenomena are not always accessible by other means.
