There are currently four generally accepted theories as to how life came to exist here on our planet (or in the universe).
- Random chance
- God created it
- Anthropic principle
Random Chance Theory
Some believe life and came to exist on our planet through sheer random chance, that is was a simple numbers game. Carl Segan popularized the Drake Equation which predicts the probability of life existing on a planet somewhere else in the universe and is integral to the SETI project (search for extra-terrestrial intelligence).
God Creation Theory
Theists, those who believe in the existence of a superior being or power, commonly called ‘God’, believe God created everything around us, including life and humans. Some theists combine scientific theories with the God creation theorizing that God followed classical rules of physics in the creation, but was ultimately the divine hand behind each step in the creation.
First articulated by Cambridge astrophysicist Brandon Carter in 1973, the principle purports that human-like being could only exist in conditions very similar to our own. So, in order to find human like beings, the would only exist in similar habitats like earth with physical conditions very similar to those found here on earth. Recently, those followers of newer quantum string theories expand upon this line of thinking with the existence of unlimited multiverses, each having its own set of laws of physics. If the number of multiverses is infinite with unlimited combinations of the laws of physics and variations in the numbers of elements, then the certainty of conditions similar to our own is certain in other universes.
One of the more recent theories is known as the biocentric theory of creation.This theory puts forth that life created the universe instead of the other way around. Much of the recent developments in this theory are the results of experiments in field of quantum mechanics. What we perceive as reality is a process that involves our consciousness. An “external” reality, if it existed, would by definition have to exist in space. But this is meaningless, because space and time are not absolute realities but rather tools of the human and animal mind.