Last week, famed physicist Stephen Hawking made news by stating that he thinks there is life elsewhere in the Universe. Hawking's speech was given as a part of a celebration of NASA's 50th birthday.
I'll admit, I am a little surprised at how much press Hawking's comments have received. Granted, his speech had all the ingredients needed for a media frenzy: a celebrity scientist making a statement on a popular topic in a public forum.
But the scientist in me is perhaps a little too jaded. Hawking is famous (and rightly so!) for his work on black holes, general relativity, and the interface of gravity (which dominates the large-scale universe) with quantum mechanics (the physics of fundamental particles). He doesn't work on astrobiology (the study of life in the Universe). And so, while Hawking's opinions are undoubtedly well-informed, he is not an expert in that field. From a scientific viewpoint, I'd personally place much more weight on the opinions of an astrobiologist than on Hawking's opinions on this subject.
And Hawking's opinion, that life may be quite common but that intelligent life is very rare, is not a groundbreaking statement. In the past couple of decades, this has become a fairly common opinion. Life has existed on the Earth for over 3 billion years, but complex organisms have existed for only the last 550 million years or so. And only in the last few million years has "intelligent" life appeared, though there is much argument over what constitutes "intelligent" life. If you go by the definition that intelligent life is capable of communicating with life on other planets, then Earth has only had intelligent life for 100 years (though this is a little too strict, I think).
So, if life is out there in the Universe and it is similar to life on Earth, then most of the life out there is probably some sort of algae soup, not friendly, space-faring gardeners. And, therefore, Hawking's remark is not earth-shattering.
But this story shows how the messenger can be just as important as the message. In the eyes of the general public, Stephen Hawking is an expert in all things astronomical. Therefore, whatever he says about life in the Universe carries much more weight with the public than anything a preeminent astrobiologist might have to say.
So, for that reason, I don't have a problem with Hawking getting credit for expounding commonly-held opinions. If he were to start claiming that aliens from Venus are taking over our planet, then I'd have a problem. But, if science and education are being served, more power to him.