Are we alone in the Universe? That seems very unlikely if you do the math: Our galaxy contains 200 - 400 billion stars and is one of several hundred billion galaxies in the observable Universe. These numbers are huge, and as a consequence even if an infinitesimally small percentage of star systems possess planets capable of harbouring life then the total number of such planets will be in the millions if not billions. The question then is, if the Universe is teeming with life, where is everybody?

The same question was asked by the Italian Nobel Prize winning scientist Enrico Fermi in 1950, and as a result the question is often called the Fermi Paradox. The paradox may finally have an answer and a simple one at that. A Danish researcher from the Niels Bohr Institute in Copenhagen has developed a computer simulation of the length of time it would take a single civilisation to explore the galaxy. His simulation was based on the scenario of a civilisation creating and launching 8 space probes with each in turn launching another eight mini-probes to search for habitable planets. His research determined that even if the probes could travel at a tenth of the speed of light (30,000 km per second) it would take about 10 billion years for the probes to explore just 4% of the galaxy.

To echo the words of the late Douglas Adams it seems that the answer to the Fermi Paradox may simply be that: “Space is big. Really big…”.

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Filed under: astronomy, science, spaceflight