The biological molecules found in oil, he avers, show only that the oil is contaminated by microbes, not that it was produced by them. Some researchers, and in particular petroleum geologists, have taken issue with Gold's proposal. They are likely to be even more put out by his new book, which says that these microbes populate the Earth's interior down to a depth of several miles and that everything we see living on the planet's surface is only a small part of the biosphere. The greater part, and the ancient part, is very deep and very hot. Absolutely, says Gold.
Spectroscopic evidence is very strong for many planetary bodies.
They interchange with the surface, so there must be lakes or oceans of liquid ethane or methane. Once you know that, it's clear they came outside from the body within. Thus, he writes, life on many other planetary bodies seems probable, even though their surfaces are either too hot or too cold to support life. Subsurface life, however, is another matter. We pulled up bugs from five kilometers down in the granite in Sweden.