9. The abundance or scarcity of energy in the future is uncertain. Since both the supply and the demand responses to energy price changes are gradual, we are not certain whether energy will be more costly in 20 or 40 years. Even intelligent, well-informed forecasters in the past have been wrong in their predictions. In any case, our economy has shown an ability to deal with very different energy prices. It seems unlikely that disaster will result from a scarcity of energy.