Are We Alone in the Universe?
At least one Doctor of Astrophysics thinks that the answer is "yes", or "for all practical purposes yes."
Dr. Howard Smith, a senior astrophysicist at Harvard, has noted that over 500 explanets (planets which orbit other stars) have been discovered so far, and they all seem to be extremely hostile to life. His conclusion is that "just right" solar systems and planets are a rare, possibly unique, event. While he does not rule out the possibility that some might exist somewhere, there may never be a means to detect them or they us, according to Dr. Smith.
I have long maintained that so many special conditions had to be "just right" for earth to support advanced life that despite the presence of 100 billion stars in this and billions of other galaxies, Earth may well be the only planet in the universe which hosts intelligent life.
The contervailing voice in the article touted Gliese 581 as a possible candidate for life. I beg to differ. It is a tiny class M dwarf with attendant outsized solar flares typical of the class. In addition, it's planet should be "tidally locked" to the star, so that the same face is always showing to the star while the other side is locked in perpetual darkness.