The chronovisor was allegedly a functional time viewer described by Father François Brune in his 2002 book Le nouveau mystère du Vatican ("The Vatican’s New Mystery"). Brune is the author of several books on the paranormal and religion.
In the book, Brune relates that the chronovisor was built by Pellegrino Ernetti (1925–1994), an Italian priest and scientist. Although Ernetti was a real person, the existence or functionality of the chronovisor has never been confirmed; its alleged capabilities are strongly reminiscent of the fictional time viewer which features in T. L. Sherred's 1947 science fiction novella, E for Effort.
In the early 1960s, Ernetti began to study the writings of François Brune, himself a Roman Catholic priest and author. Ernetti allegedly ended up helping Brune construct the machine as members of a team which included twelve world-famous scientists. He identified two of them as Enrico Fermi and Wernher von Braun. The chronovisor was described as a large cabinet with a cathode ray tube for viewing the received events and a series of buttons, levers, and other controls for selecting the time and the location to be viewed. It could also locate and track specific individuals. According to its inventor, it worked by receiving, decoding and reproducing the electromagnetic radiation left behind from past events. It could also pick up the audio component or sound waves emitted by these same events.
Ernetti lacked hard evidence for these claims. He said that he had observed, among other historical events, Christ's crucifixion and photographed it as well. A copy of this image, Ernetti said, appeared in the 2 May 1972 issue of La Domenica del Corriere, an Italian weekly news magazine. A near-identical (mirror-image) photograph, however, of a wood carving by the sculptor Lorenzo Coullaut Valera turned up and succeeded in casting doubt upon Ernetti's statement.
Using the chronovisor, Ernetti said that he had witnessed, among other scenes, a performance in Rome in 169 BC of the lost tragedy, Thyestes, by the father of Latin poetry, Quintus Ennius. Dr. Katherine Eldred of Princeton University is the author of an English rendition of the text which is included as an appendix to the U.S. printing of Peter Krassa's book on the Chronovisor (see below). Eldred believes that Ernetti actually wrote the supposedly ancient play himself. As provided by an anonymous relative of Father Ernetti, there was a deathbed confession, included in the U.S. edition of the play, that Ernetti had written the text of the play himself and that the "photo" of Christ was indeed a "lie". According to the same "source", however, Ernetti also affirmed that the machine was genuinely functional.
Brune, however, does not believe Ernetti's "confession" and is convinced that the authorities had coerced Ernetti into making a false confession.
The alleged existence of the chronovisor has fueled a whole series of conspiracy theories,[who?] such as that the device was seized and is actually used by the Vatican or by those who secretly control governments and their economies all around the world.