How Aliens Work

At How Stuff Works Craig Freudenrich has put together a primer on "How Aliens Work". He lays out the ground rules for alien physiology:

1. "Alien life would be governed by laws of physics and chemistry."
2. "Alien life would be based on some type of chemistry (eliminating the sci-fi concept of pure-energy beings)." What type of chemistry will be determined by the environment, including the available solvent (such as water or methane), temperature, pressure, available energy sources, and the presence of complex molecules, especially an "informational molecule" like DNA.
3. Aliens larger than microbes would have some equivalent of cells. "We would not expect to find a light-years wide, single-celled organism like that portrayed in the original Star Trek episode "The Immunity Syndrome.""
4. "Organ systems would be adapted to environmental conditions such as temperature, moisture and gravity"
5. "Alien organisms would probably have similar ecological structures to life on Earth."

And the most important take home message?

As you can see, life of any kind is intimately tied to its environment, so the characteristics of the planet would be extremely important in determining the characteristics of the life form.

Read the full article for all the details.

(via The World in the Satin Bag)

Image: Creatures like the gargantuan Space Amoeba from the Star Trek ToS Episode "The Immunity Syndrome" probably don't exist.