Read "Can Solar 'Belch' Theory Solve Sun Paradox?", here.The notion that the earth and cosmos are billions of years old continues to present serious problems for evolutionary scientists. For instance, billions of years ago, the sun would only have glowed faintly, leaving nearby earth totally frozen. But with no liquid water on earth's surface, how could life have evolved and become fossilized so long ago?This conundrum has been called the "faint young sun paradox," and after 25 years of research, it remains just as problematic as ever. Scientists have tinkered with models of what they thought were atmospheres that might have kept earth warm. But sunlight would have prevented an ammonia-caused greenhouse earth, and earth's oldest rocks show that the atmosphere was not dominated by the mild greenhouse gas carbon dioxide either.