Natural gas is an odorless gas ( a chemical is added to give it an odor so that leaks can be detected). Natural gas is lighter than air and consists mostly of the simple hydrocarbon methane (CH4). It is the cleanest-burning fossil fuel, since its combustion produces mainly carbon dioxide and water vapor. Natural gas often requires little refining before being used and provides for about 24-26% of the energy needs in the United States.

A recent drilling project in Sweden has raised some interesting questions about the origins of natural gas. The well lies north of Stockholm in a meteorite impact crater called the Siljan Ring. Dr. Thomas Gold suggested that the well be drilled there for several reasons.

First, the Siljan Ring lies on a granite shield from which most overlying sedimentary rock has been stripped away by Ice Age glaciers, thus making it unlikely that gas found here would be of biological origin.

Second, the impact of the meteorite millions of years ago crushed the granite below, providing cracks and fissures that would allow the abiogenic gas to migrate upward. Seismic data had indicated that there were such porous zones deep in the granite, along with a series of dense layers that could be cap rocks.

Third, traces of oil and gas had already been found in the area. Tar seeping from the granite had been used by the Vikings to seal their ships long ago, and lakes in the Siljan Ring sometimes bubble up methane.

Drilling began in 1986, and, while no great reservoirs of methane have yet been found, it is still unclear whether the traces that have been collected are abiogenic or biological in origin. If a large reservoir of natural gas is found in the Siljan Ring, it could radically change the world's energy picture in many ways.

Science Fiction writing expresses imaginary new ideas or activities which are based on scientific realities. Science Fiction stretches the reader's understanding by presenting science concepts from unusual perspectives.

The story of Dr. Gold's research in the Siljan Ring is true, but the University's Center for Radiophysics and Space Research is fiction.

Think about how world events might be changed if great quantities of natural gas were to be found in the Siljan Ring. What else might be found there? Imagine meteorites from other planets slamming into the Earth -- what might have happened?