Читать книгу Neurobiology For Dummies - Frank Amthor - Страница 11

According to astronomers and astrophysicists, the universe as we know it came into existence about 14 billion years ago. After several cycles of star formation, our solar system, including the earth, formed about 4.5 billion years ago. The earth was too hot for life for about a billion years, as it continued to be bombarded by the solar system debris from which it was formed.

Eventually most of the solar system debris stuck to one or another planet, or stabilized in relevantly permanent orbits such as the asteroid belt between Mars and Jupiter. Earth cooled for about 1 billion years, and life arose. No one knows how. Some scientists are suspicious that life arose almost as soon as the earth was cool enough, suggesting either that it must occur almost automatically given the right conditions, or it came from elsewhere and established a foothold as soon as it was possible.