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How will we know that we've found alien life ?

January 2, 2020 | Comment icon 27 comments

What exactly are the telltale signs of alien life ? Image Credit: NASA/JPL-Caltech
Even if we were to discover evidence of extraterrestrial life, would we even be able to recognize it ?
In a recent article for 'The Conversation', Peter Vickers - an associate professor in philosophy of science at Durham University - discusses why we need to 'expect the unexpected'.

If we discovered evidence of alien life, would we even realize it? Life on other planets could be so different from what we're used to that we might not recognize any biological signatures that it produces.

Recent years have seen changes to our theories about what counts as a biosignature and which planets might be habitable, and further turnarounds are inevitable. But the best we can really do is interpret the data we have with our current best theory, not with some future idea we haven't had yet.

This is a big issue for those involved in the search for extraterrestrial life. As Scott Gaudi of Nasa's Advisory Council has said: "One thing I am quite sure of, now having spent more than 20 years in this field of exoplanets... expect the unexpected."

But is it really possible to "expect the unexpected"? Plenty of breakthroughs happen by accident, from the discovery of penicillin to the discovery of the cosmic microwave background radiation left over from the Big Bang. These often reflect a degree of luck on behalf of the researchers involved. When it comes to alien life, is it enough for scientists to assume "we'll know it when we see it"?

Many results seem to tell us that expecting the unexpected is extraordinarily difficult. "We often miss what we don't expect to see," according to cognitive psychologist Daniel Simons, famous for his work on inattentional blindness. His experiments have shown how people can miss a gorilla banging its chest in front of their eyes. Similar experiments also show how blind we are to non-standard playing cards such as a black four of hearts. In the former case, we miss the gorilla if our attention is sufficiently occupied. In the latter, we miss the anomaly because we have strong prior expectations.

There are also plenty of relevant examples in the history of science. Philosophers describe this sort of phenomenon as "theory-ladenness of observation". What we notice depends, quite heavily sometimes, on our theories, concepts, background beliefs and prior expectations. Even more commonly, what we take to be significant can be biased in this way.

For example, when scientists first found evidence of low amounts of ozone in the atmosphere above Antarctica, they initially dismissed it as bad data. With no prior theoretical reason to expect a hole, the scientists ruled it out in advance. Thankfully, they were minded to double check, and the discovery was made. Could a similar thing happen in the search 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 recognised on closer analysis or with a non-standard theoretical approach.
However, we shouldn't exaggerate the theory-ladenness of observation. In the Muller-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 endeavour – 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, Associate Professor in Philosophy of Science, Durham University

This article is republished from The Conversation under a Creative Commons license.

Read the original article.The Conversation

Source: The Conversation | Comments (27)

Recent comments on this story
Comment icon #18 Posted by Manwon Lender 3 years ago
Oh my.
Comment icon #19 Posted by Sir Wearer of Hats 3 years ago
With the added caveat that if it’s intelligent life, it would be studiously avoiding us because we’re ****s.
Comment icon #20 Posted by DanL 3 years ago
Life we might recognize but intelligence may be a lot harder. We are very egocentric about which of our senses can be used to communicate. There is no certainty that a totally alien species might use another sense than seeing or hearing as a basis for communication and there is not even a certainty that they would use a sense that we even have. Sharks can sense the electric pulses of a body. An alien might use this as we do speech and be yelling at us and we wouldn't recognize that it was even trying to communicate. There might also be a difference in time scale. in a frigid environment, proce... [More]
Comment icon #21 Posted by third_eye 3 years ago
Take me to your Burger King....  ~ *Almost an alien* Does that sound like a TV ad I'd like to see or what....  ~
Comment icon #22 Posted by thelion318 3 years ago
The octopus has a biology not like any other creature on Earth. It *could* be an alien life form and we currently do not recognize it as such. Same for many bacteria "discovered" each year. Bias blinds us
Comment icon #23 Posted by GlitterRose 3 years ago
Picturing an octopus flying a UFO is hilarious.
Comment icon #24 Posted by ChrLzs 3 years ago
No, it isn't unlike any other creature.  Yes, it has an unusually large brain and a more 'evolved' DNA than most species, but that simply means that its environment and the evolutionary path it took was a bit more involved (or just plain 'luckier') than most other species.  It also uses, like several marine species, a method that allows changes to its DNA to happen more quickly than 'normal'.  Look up 'RNA editing'. You should also maybe look up its closest relatives, and then examine other similarly unusual species - especially in terms of marine biology, like squid and cuttlefish.  Try Britt... [More]
Comment icon #25 Posted by ocpaul20 3 years ago
Maybe they have vehicles which supply them with life support. Very much like robots where they are the 'brains', daleks, or  the tripods in war of the worlds? One of the Men in Black aliens had an alien within(controlling) a human-shaped body too.
Comment icon #26 Posted by Robotic Jew 3 years ago
I picture it to be something like a human body but the octopus is on top like a Toupee.
Comment icon #27 Posted by stereologist 3 years ago
The octopus is clearly a mollusc and has an earthly origin. The article that was published has been soundly rejected by their peers. A mistake often made and I have made it myself at times is that a published paper is a paper that gets to be reviewed by scientists. Publication does not mean it is correct.  

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