Alien Life

A common TV sci-fi theme is: an Earth space probe, or such, goes into the depths of space and brings back a deadly virus or bacteria thus creating wide-spread havoc here on Earth. What are the chances?

Years ago, I read Lewis Thomas' book, "Lives of a Cell". Thomas makes an excellent point about the small chance that alien life could impact life here on Earth. In order for it to impact Earth-life, it would have to have DNA (or RNA) similar to ours. The chances that on a separate planet located in the reaches of space the same genetic structure would evolve are so tiny that, ... well ... probably wouldn't happen. And it is through either DNA or RNA that the various microbes interact with us either giving us a cold or the flu or a sinus infection, etc.

So here is an idea for a great sci-fi novel: the sands here on Earth, and they are vast, begin to disappear. And, of course, it is an alien life form that was causing the destruction! The impact og losing our sand would much greater than you might think. In fact, sand is so important that Saudi Arabia had to import some from the US years ago for industrial uses -- their sand was too fine to use. Food for thought.