Cosmic Corner: The Search is On!



Have I got your attention now? One of the most burning questions about the cosmos is ‘Are we alone in the universe?’ Although I cannot definitively provide a solid answer to that (as, currently, no one can), I hope to impart some insight into the prospect of extra-terrestrials. This article will hopefully leave you with a bit more knowledge about where aliens might be found, and what research into their existence is currently underway.

So where could we potentially find aliens? Biology on Earth indicates liquid water is essential for life to flourish – this isn’t to say that all extra-terrestrials necessarily require water, but it’s a good place to start. Particular conditions must be met before liquid water will be retained on a planet: there must be a thick enough atmosphere to prevent evaporation and the planet must fall within a specific range of temperatures, to maintain the liquid state. (This is one drawback of the possibility for life on Mars: frozen water is stored in polar caps during winter and released via sublimation in summer, so it never remains as a liquid on the planet.)

As you can see, it’s not easy to find the perfect ‘Goldilocks’ planet to support life. Currently Mars has been the prime target of our extensive physical search for extraterrestrial life. But our search isn’t limited to physical inspection. In fact, several methods are currently underway to continue the search.

It is not feasible to send unmanned space probes to distant stars, as the travel time alone provides a significant barrier: hundreds of years may pass before the probe reaches its destination, plus the equally long journey of information back to Earth.

A more feasible option is radio transmissions. Astronomers are scanning the skies trying to detect radio waves potentially sent by an intelligent species. This is a promising option for detecting signs of life, as radio waves can travel over large distances without significant degradation of their signal from interstellar debris.  

SETI, or the Search for Extra-Terrestrial Intelligence, has carried out analysis of radio transmissions from the area of over 60 stars, but have yet to find any binding evidence of alien life.

In the 1960’s, Frank Drake proposed an equation that models how many potentially life-supporting planets exist in our galaxy:


I’ll spare the technical details, but the gist is that the number depends on many variables such as the fraction of Earth-like planets on which life actually evolves, and the fraction of those life-forms that exhibit intelligence. Most of the parameters have significant uncertainty, but by arbitrarily making them one set of possible values, the number we arrive at is 10; i.e. in our entire galaxy, there may be as few as 10 worlds supporting intelligent life.

Infrared telescopes and stellar spectra are also budding technologies in the search. But although we have yet to find any concrete evidence, we mustn’t get discouraged. In a field so vast and so uncertain, our search has really only just begun.

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