The Ubiquitous Nature of Life
…Are we alone in here?
While not evidence of alien visitation, the question of whether it is possible that there is intelligent life like our own out there somewhere among the stars must be answered first, for without first determining that such a possibility is even possible there is no further room for discussion. After all, if Earth is the only planet among 300 sextillion stars on which life exists, the prospect of alien visitation becomes a moot point. Once it is accepted that intelligent life is not only likely but even a near certainty, however (as most scientists have come to believe), then the prospect that we may be candidates for visitation must be at least considered.
The best estimate of the age of the universe as of 2013 is 13.798 ± 0.037 billionyears but due to the expansion of space humans are observing objects that were originally much closer but are now considerably farther away (as defined in terms of cosmological proper distance, which is equal to the comoving distanceat the present time) than a static 13.8 billion light-years distance. It is estimated that the diameter of the observable universe is about 28 billion parsecs (93 billion light-years), putting the edge of the observable universe at about 46–47 billion light-years away.