Given Symmetry of the Universe, Why Not Life Elsewhere?

The guy who came to fix my deck Wednesday morning asked me if I believe in life on Mars. Personally, he was skeptical. “You’d think they would at least have left a fingerprint, a strand of hair, a piece of a spaceship,” he said.

To be sure, the microscopic hot-dog-shaped forms that NASA and Stanford scientists dug out of a rock from Mars were hardly impressive. Even the most “pro-life” researchers haven’t settled on whether the forms were simply dried up mud cracks rather than fossils.

Still, there are good reasons to believe that life might be abundant in the universe--aside from the well-known fact that our sun is a rather ordinary star in an ordinary galaxy among hundreds of billions of similar galaxies.

But the best arguments may well come from the physics of how matter likes to arrange itself in space.

Take a look around our corner of the universe and it’s hard not to be impressed at how certain mathematical patterns appear again and again, the same themes repeated in endless variation.

Balls tossed into the air carve out elegant parabolas, as does water flowing from fountains. Rivers and trees and blood vessels and lightning branch out in surprisingly similar ways. Cream swirling in coffee and stars spiraling in galaxies arrange themselves according to the same formula as water spinning down the drain.

Soap bubbles meet at 120-degree angles without ever studying math, and the oxygen and hydrogen atoms in water meet at precisely 105 degrees. The symmetry of snowflakes reflects the strength and arrangement of water’s hydrogen bonds.

Geometry really does grow on trees. Matter falls into formations that are guided by the forces that prevail in our universe--gravity, electromagnetism and nuclear forces. Every behavior of every proton and neutron and electron is choreographed by the interplay of these forces.

“Why do meandering snakes, meandering rivers and loops of string adopt the same pattern?” asks Peter S. Stevens in “Patterns in Nature.” “A look behind the footlights reveals that nature has no choice in the assignment of roles to players.”

What does this have to do with the prevalence of life? All life on Earth is based on carbon, and carbon--like every other element--likes to rearrange itself in certain predetermined ways.

Under very high heat and pressure, carbon atoms join to form strong, tight tetrahedrons, bending and separating light into the sparkly colors of diamond. Arranged in flat six-atom hexagons like chicken wire, carbon is slippery graphite, good for pencils and lubricants.

Carbon is versatile because buzzing around each atom are four loosely attached electrons that act like electrical sockets where other atoms--including other carbon atoms--can plug in. Therefore, carbon likes to make long chains. And long chains of complex molecules are the basis of proteins, DNA and all the other ingredients of life.

Carbon’s structure encourages it to behave in some ways and not in others. Depending on its surroundings, it will tend to form the same kinds of pattern over and over again, no matter where it is.

In the same way, oxygen and hydrogen form ice on Jupiter’s moon Europa just as they do on Earth. The omnipresence of the same players, guided by the same forces, ensures that the same chemistry prevails.

Given the right conditions, therefore, many scientists believe carbon-based life could be rather common. The key is: “the right conditions.” Researchers are excited about the possibility of life on Europa or ancient Mars because they think these places might have had the right ingredients: water, moderate temperature, relative stability, a source of energy and, of course, carbon compounds.

That isn’t to say that life exists elsewhere. But given the right chemistry in the right conditions, who knows? Somewhere in the universe, tiny hot-dog-shaped life forms might be raining down like snowflakes.