Alien Life Is Out There, but Our Theories Are Probably Steering Us Away from It

for extraterrestrial life? Scientists studying planets in other solar systems (exoplanets) are overwhelmed by the abundance of possible observation targets competing for their attention. In the last 10 years scientists have identified more than 3,650 planets - more than one a day. And with missions such as NASA’s TESS exoplanet hunter this trend will continue.

Each and every new exoplanet is rich in physical and chemical complexity. It is all too easy to imagine a case where scientists do not double check a target that is flagged as “lacking significance”, but whose great significance would be recognized on closer analysis or with a non-standard theoretical approach.

However, we shouldn’t exaggerate the theory-ladenness of observation. In the Müller-Lyer illusion, a line ending in arrowheads pointing outwards appears shorter than an equally long line with arrowheads pointing inwards. Yet even when we know for sure that the two lines are the same length, our perception is unaffected and the illusion remains. Similarly, a sharp-eyed scientist might notice something in her data that her theory tells her she should not be seeing. And if just one scientist sees something important, pretty soon every scientist in the field will know about it.

History also shows that scientists are able to notice surprising phenomena, even biased scientists who have a pet theory that doesn’t fit the phenomena. The 19th-century physicist David Brewster incorrectly believed that light is made up of particles travelling in a straight line. But this didn’t affect his observations of numerous phenomena related to light, such as what’s known as birefringence in bodies under stress. Sometimes observation is definitely not theory-laden, at least not in a way that seriously affects scientific discovery.

We Need to Be Open-Minded
Certainly, scientists can’t proceed by just observing. Scientific observation needs to be directed somehow. But at the same time, if we are to “expect the unexpected”, we can’t allow theory to heavily influence what we observe, and what counts as significant. We need to remain open-minded, encouraging exploration of the phenomena in the style of Brewster and similar scholars of the past.

Studying the universe largely unshackled from theory is not only a legitimate scientific endeavor – it’s a crucial one. The tendency to describe exploratory science disparagingly as “fishing expeditions” is likely to harm scientific progress. Under-explored areas need exploring, and we can’t know in advance what we will find.

In the search for extraterrestrial life, scientists must be thoroughly open-minded. And this means a certain amount of encouragement for non-mainstream ideas and techniques. Examples from past science (including very recent ones) show that non-mainstream ideas can sometimes be strongly held back. Space agencies such as NASA must learn from such cases if they truly believe that, in the search for alien life, we should “expect the unexpected”.

Peter Vickers is Associate Professor in Philosophy of Science, Durham University. This articleis published courtesy of The Conversation.