P.5
Another problem limiting our understanding of the universe is that we don't live very long. The universe, it is believed, is about fifteen billion years old. So, in our short life spans, we don't see many of the changes that occur in the universe. It can be thought of as trying to understand what happens in the course of a whole year by only looking at what happens within one second. Though we may be able to see stars and other phenomena at different stages in their development, we cannot measure the course of many cosmic phenomena through their life spans. We cannot have a comprehensive knowledge of the universe if we have only been aware of it for such a short time, as modern computers are able to simulate changes in the universe occurring over billions of years.