Are We Alone?

Humankind’s Search for Extra-terrestrial Civilizations

1. INTRODUCTION

Sometimes I think we’re alone in the Universe, and sometimes I think we’re not. In either case the idea is quite staggering.

— Attributed to Arthur C. Clarke, celebrated science and science fiction writer, futurist, and inventor

On December 16, 2014, in the Fall Meeting of the American Geophysical Union in San Francisco, scientists announced that NASA’s Curiosity rover detected sudden spikes of methane in the Martian atmosphere. The scientists also confirmed for the first time the presence of carbon-based organic molecules in a Martian rock sample.

Why is this newsworthy?

Because this could indicate that a carbon based life-form could have existed on the Red Planet at some point during its cosmic evolution. This is also a clue that Mars may currently harbor life, possibly in a microbial form. Life as we know it on Earth, produces significant amounts of methane, thus the spikes in methane in the Martian atmosphere may signal a similar form of life on the planet. However, since methane can also be produced by geological means, the detection of methane is not directly indicative of signs of past or present life forms. Rather, it suggests the possibility that Mars once had the ingredients required for life, and might still harbor them—one only needs to know where to look. The origin of Mars’ methane has become an active area of research with missions such as Curiosity and India’s Mars Orbiter keenly measuring the changes in its abundance.

On the other hand, the answer to the question of whether intelligent life exists somewhere in the Universe is still unknown. Humankind has long been intrigued by the idea of whether life on Earth is unique in the vastness of space, or whether our Galaxy is swarming with extraterrestrial civilizations.

Today, most scientists believe that advanced life forms exist somewhere else in the Universe: In a documentary series, the famous British astrophysicist Stephen Hawking argued that it is ‘perfectly rational’ to assume intelligent life exists elsewhere in the Universe. Hawking believes that primitive life is very common but intelligent life is probably fairly rare.