SILICON BASED LIFE, MYTH OR REALITY?

This is an intriguing question that scientists ponder in the search for alien life. While all known life on Earth is carbon-based, using DNA and RNA as the basis for heredity, alternative chemistries for life are certainly possible in theory.

Let's start with why carbon is so suitable for life on Earth. Carbon has four valence electrons, allowing it to form strong bonds with many other elements like hydrogen, oxygen and nitrogen. This makes it ideal for building the complex molecules necessary for life, proteins, fats, nucleic acids and carbohydrates. Carbon atoms can also link together in chains and rings, creating molecular diversity.

But carbon is not the only element with these properties. Silicon, for example, is just below carbon on the periodic table and shares some of its bonding capabilities. Silicon atoms can form strong bonds with oxygen, hydrogen and other nonmetals. Silicon compounds are also chemically stable over a wide temperature range. This has led some scientists to propose the concept of "silicon-based life".

However, silicon compounds tend to be less flexible than their carbon counterparts. Silicon-oxygen bonds are also more rigid and brittle. This could limit the complexity of silicon-based polymers and macromolecules needed for organisms. But given the vast possibilities of chemistry, alternative elements like boron, germanium or phosphorus may also allow for life-enabling compounds.

The vast number of exoplanets being discovered raises the possibility of non carbon-based alien biospheres. The conditions that led to carbon-based life on Earth may differ radically on other worlds.

Though carbon is perfect for our type of life, the basic requirements for life are more general: stable organic-like compounds, hereditary molecules, and chemical reactions driven by an energy source. If the right conditions exist, alternative elements beyond carbon may enable non carbon-based lifeforms with completely alien biochemistries - silicon "organisms" swimming in arsenic "oceans" perhaps.

Signing off,

LOKI