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| Cherenkov radiation |
We know that the special theory of relativity states that the speed of a body with rest mass greater than zero must be less than the speed of light in a vacuum, i.e., about 300,000 km/second. However, sometimes examples are given that seem to indicate, at first glance, that this limit can be transgressed. Let's look at them:
Astrologers have been answering this question in the affirmative since time immemorial. It’s true that astrology has been discredited since a few centuries ago, to the point that another name had to be found for the science dedicated to the study of the stars (astronomy = laws of the stars). Despite which, in this supposedly scientific age, the mainstream media dedicate significant space to horoscopes and other astrological products.
Sometimes the influence of the moon has been confirmed. Since ancient times it was observed that the tides are related to the position of the moon in the sky, although it was not known how this influence could take place. To support the theory of Copernicus against that of Ptolemy, Galileo formulated a theory, according to which the tides are not due to the attraction of the moon, but to the translational movement of the Earth around the sun. In this case Galileo was wrong, because the influence of the moon is real, although it was not explained until Isaac Newton formulated the theory of universal gravitation.
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| C.S. Lewis |
Apart from the Chronicles of Narnia, C.S. Lewis wrote a science fiction trilogy and left an unfinished fourth novel, The Dark Tower, which was published as-is after his death. In this novel, Lewis offers an argument against the possibility of time travel, not commonly advanced in this context. Usual arguments are a version of the Fermi paradox, or the enumeration of the paradoxes that could occur if it were possible to travel to the past, and in some cases also to the future.
The argument offered by C.S. Lewis consists of two parts:
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| Andy Weir |
Andy Weir became famous with his 2011 sci-fi novel The Martian, in which an astronaut is mistakenly abandoned on Mars when the third expedition must be hastily canceled because of a violent dust storm. The novel was the basis for a film, which bears the same title, and which made its author famous.
Weir is not a prolific writer. In 2021,
his third novel, Project Hail Mary,
was published. In my opinion, this is one of the seven best science fiction
novels of all time. My other six favorite works in this genre can be seen here.
Project Hail Mary is a hard science fiction novel about space adventures typical of the genre. It deals with interstellar travel at relativistic speeds, encounter with extraterrestrial intelligences, or the invasion of the solar system by extraterrestrial life forms that threaten our survival. All this is integrated in a coherent way.
