In the long list of modern fears, bloodthirsty aliens may not rank near the top. We have more immediate worries, from terrorism and bioengineered (or not) global epidemics to nuclear holocaust and natural disasters.
However, the notion that other intelligences exist out there in the universe is pervasive in popular culture. Mirrors to our own history, in particular colonial exploitations, aliens are often portrayed as evil invaders bent on coming here to wreak havoc.
How realistic are these scenarios, given what we know now about astronomy and the possibility of life in other worlds?
Stephen Hawking, among others, has suggested that we should be very careful with aggressive aliens — that, in fact, we should be as stealthy as possible, lest we reveal our presence and location to predatory ETs in our cosmic neighborhood.
There are three parts to this. The first concerns the existence of other worlds with habitable conditions — that is, that can harbor life as we know it. Thanks to the efforts of the many planet hunters out there, in particular the remarkable results from NASA's Kepler mission, we now know that most stars have planets surrounding them. Thousands of these planets have been identified, and, among these, several have properties similar to Earth: rocky and within the habitable zone of their main star. Although the majority of these orbit small and cooler M dwarf stars, where conditions for life may be very harsh indeed, the fact is that we should expect a few Earth-like worlds within a distance of about 1,000 light years or so.
We should be more afraid of those in government and academia who know there are aliens out there, but won't tell us the truth. To read more, click here.