In this second, significantly revised and expanded edition of his widely popular book, Webb discusses in detail the (for now!) 75 most cogent and intriguing solutions to Fermi's famous paradox: If the numbers strongly point to the existence of extraterrestrial civilizations, why have we found no evidence of them?
Reviews from the first edition:
"Amidst the plethora of books that treat the possibility of extraterrestrial intelligence, this one by Webb ... is outstanding. ... Each solution is presented in a very logical, interesting, thorough manner with accompanying explanations and notes that the intelligent layperson can understand. Webb digs into the issues ... by considering a very broad set of in-depth solutions that he addresses through an interesting and challenging mode of presentation that stretches the mind. ... An excellent book for anyone who has ever asked ‘Are we alone?’." (W. E. Howard III, Choice, March, 2003)
"Fifty ideas are presented ... that reveal a clearly reasoned examination of what is known as ‘The Fermi Paradox’. ... For anyone who enjoys a good detective story, or using their thinking faculties and stretching the imagination to the limits ... ‘Where is everybody’ will be enormously informative and entertaining. ... Read this book, and whatever your views are about life elsewhere in the Universe, your appreciation for how special life is here on Earth will be enhanced! A worthy addition to any personal library." (Philip Bridle, BBC Radio, March, 2003)
Since gaining a BSc in physics from the University of Bristol and a PhD in theoretical physics from the University of Manchester, Stephen Webb has worked in a variety of universities in the UK. He is a regular contributor to the Yearbook of Astronomy series and has published an undergraduate textbook on distance determination in astronomy and cosmology as well as several popular science books. His interest in the Fermi paradox combines lifelong interests in both science and science fiction.
The author concentrates on planetary systems beyond our own but starts with life on Earth, which is the only life we know to exist, and which provides guidance on how best to search for life elsewhere. Planets are the most likely abode of life and so we start the quest with the search for planets beyond the Solar System – exoplanets. The methods of searching are outlined and the nature of hundreds of exoplanetary systems so far discovered described. In the near future we expect to discover habitable Earth-like planets. But are they actually inhabited? How could we tell? All will be revealed.
This full color book is written for everybody who wants to stay in close contact with the latest on possible life on other planets.
David Harland considers the issue of life on Mars in parallel with the origin of life on Earth. At the time the Viking instruments were designed, it was thought that all terrestrial life ultimately derived its energy from sunlight, and that the earliest form of life was the cyanobacteria with chlorophyll for photosynthesis. It was assumed the same would be the case on Mars and that microbial life would be on or near the surface that the Vikings had sampled.
No sooner were the results from the Viking instruments in, than it was discovered that there was an even older type of microbial life on Earth when, in 1977 ‘black smokers’ were found in volcanically active parts of the ocean floor, at depths of several kilometres. Removed from sunlight, these archaea (literally, ‘the old ones’) live off the minerals released by the hydrothermal activity. Subsequently our view of life was further revised when ‘extremophiles’ were discovered thriving in acidic, salty, alkaline, very hot, very cold and radiation soaked environments previously considered lethal. Although the Vikings had found no sign of organics, and the surface was extremely hostile, suggesting that life had never gained a foothold, the discovery of microbes living far beneath the surface of the Earth raised the possibility of life below the surface of Mars, where there may be water-ice and/or hydrothermal activity. Perhaps, because the microbes were beyond the reach of the Vikings’ instruments, the negative result was premature.
Following the negative tests for biological activity by the Vikings, NASA – in the belief that Mars was once warm and wet, as the erosional features on the surface suggest – decided to ‘chase the water’ in the hope of establishing that conditions on Mars were once suitable for life, although this would not prove that life had developed. The targets selected (from many) were what seemed to be an outflow channel, a dry lake and a patch of minerals emplaced by hydrothermal activity. In 1997 Mars Pathfinder landed in an outflow channel where it released the small Sojourner rover to perform chemical analyses of nearby rocks. NASA followed up in 2004 with the much larger Mars Exploration Rovers, which were equipped to act as mobile field geologists. One was landed in what seemed to be a dried up lake bed inside a crater, and the other set down in an area that a remote-sensing orbital survey had identified as haematite, a likely indicator of hydrothermal activity. Both of these missions have yielded evidence that conditions were once conducive to the development of life.
In parallel with these NASA projects, the European Space Agency developed the Mars Express remote-sensing orbiter, which has detected traces of methane that may have been released by microbes. If microbial life is found on Mars, will it be based on DNA? Will this indicate that life developed independently? Or that it has characteristics in common with the most ancient forms of terrestrial life? If life is found on two planets in the same planetary system, this would favour the panspermia hypothesis. And if martian life is radically different, then in light of the discovery of planetary systems around other stars, this would, as remarked by Philip Morrison of MIT, "transform life from the status of a miracle to that of a statistic". These are all questions that the exploration of Mars for life are aimed to answer.
The new profile of scientists in fundamental physics ideally involves the merging of knowledge in astroparticle and particle physics, but the duration of modern experiments is such that people cannot simultaneously be practitioners in both. Introduction to Particle and Astroparticle Physics is designed to bridge the gap between the fields. It can be used as a self-training book, a consultation book, or a textbook providing a “modern” approach to particles and fundamental interactions.