Conclusion

Abstract

The first four chapters of this book deal with unique circumstances, at least in terms of the Earth. It is probably obvious even to the casual reader that we might well expect similar circumstances to apply on terrestrial-type planets elsewhere in the universe, suggesting that life, at least in its simplest form, is likely to exist in many other places. The vast distances involved, even in galactic terms, also suggests that we are very unlikely to actually encounter extraterrestrial life. Those who argue for the possibility of life on Mars would take exception to this view, and that discussion is likely to continue for some time.