Back in elementary school, our science teacher asked us how we know if something is alive. After a bit of prodding, we were able to say that a living thing eats, excretes, grows and — eventually — dies.
Then our teacher lit a candle and asked, “Is this flame alive?”
Like all living things, the flame eats (fuel), excretes (smoke and heat), grows (when it’s fed anything flammable) and dies.
In a sense, a flame really is a different form of life.
Perhaps, say some researchers, life on other planets may be even more different from us than that flame. In fact, in an interview in Science Daily, Dr. Johannes Leitner said: “It is time to make a radical change in our present geocentric mindset for life as we know it on Earth. Even though this is the only kind of life we know, it cannot be ruled out that life forms have evolved somewhere that neither rely on water nor on a carbon and oxygen based metabolism.”
To consider the possibilities of non-carbon, non-oxygen based life, a consortium is investigating the properties of solvents other than water. For example, they’re looking at ammonia — a solvent that can remain liquid at ultra-cold temperature. And they’re looking at sulphuric acid, because “sulphuric acid can be found within the cloud layers of Venus and we now know that lakes of methane/ethane cover parts of the surface of the Saturnian satellite Titan.”
What kind of animal could thrive in a deadly acid sea? The answers may not be arriving tomorrow, but they may be available sooner than we think.
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