Three Explanations for Why Aliens Might Not Have Visited Earth: Distance, Energy Costs, and Habitability
To the point
Professor Carol Oliver argues that aliens might not visit Earth because vast distances make interstellar travel impractical, the energy required to reach near-light speeds is prohibitive, and Earth’s life and oxygen-rich atmosphere could be hostile to outsiders.
Behold a Pale Horse
Milton William Cooper
In Plain Sight: An investigation into UFOs and impossible science
Ross Coulthart
Vespera II Exploration Station with Smart Technology
The Extraterrestrial Species Almanac: The Ultimate Guide to Greys, Reptilians, Hybrids, and Nordics (MUFON)
Craig Campobasso
Our recommendations from Amazon