Everything about life is as unique as it is mysterious. Earth is the only planet in our universe that science can confirm has and can sustain life, but what science cannot explain is how this life started.
Paul Davies is the Director of the BEYOND: Centre For Fundamental Concepts Of Science at Arizona State University. As a theoretical physicist, his research focuses on answering some of life's big questions, like how life started and what life is.
I think it is slightly more likely that life started on Mars and came to Earth and that our ancestors from long ago were actually martians.
"We absolutely don't know what turns non-life into life. It could have been a chemical fluke so unlikely it would never happen twice, or it could be something built into the laws on nature, although we have never discovered any life principle," Davies told HuffPost Australia.
"There is nothing we know that compels matter to organise itself into life, nothing. It doesn't mean that it doesn't, but we haven't discovered that there is any principle underpinning matter to make it do that."
Davies' research belongs to his dedication towards making sense of the quintessential questions of our time and existence.
"Can life happen more than once? It becomes extraordinarily interesting and important and profound and ... that is the great cosmic question," he said.
"Do we live in a universe that is fundamentally bio friendly, in which life will pop up wherever conditions permit or do we live in a sterile universe with life on Earth being a bizarre freak accident and we are it and that is all there is?"
To explain how life on Earth could have started, and to understand if life could exist elsewhere in the universe, Davies looks to Earth's neighbouring planet -- Mars -- to provide some possible explanation.
In fact, Davies believes that it is likely life started in Mars long before it did on Earth and then was transferred to Earth via rocks that were knocked from the red planet's surface.
"I think it is slightly more likely that life started on Mars and came to Earth and that our ancestors from long ago were actually Martians and we are the descendants of microorganisms that were transferred from Mars to Earth about 3.8 billion years ago," Davies said.
"The evidence for that is... not very great but we certainly know that it is possible and it seems slightly more likely that life would start on Mars than on Earth," Davies said.
Davies explains this theory by citing the nature of living things to transfer and duplicate information.
"We [researchers] would like to understand the principles that operate within matter that distinguish it from non-living matter, and it clearly has something to do with information. I think it is obvious that living organisms replicated genetic information, but they also process information from their surroundings.
"If you think of bacteria for example, it won't just wait there, it is active. It is coupled to its environment, it gathers information about its environment, processes it and responds in an appropriate way."
The overarching and fundamental question of how life actually started remains unanswered.
Davies explains that without a mechanism to explain what made the matter organise itself into life, scientists cannot explain how probable the occurrence of life was, or could be in the future.
"So you might say how likely is it that a fairy will materialise at the end of my bed? I could say to you if you could tell me what was involved I can work out the numbers," he said. "If what you are saying is all the molecules of air spontaneously assemble themselves into a fairy-like shape, yes I can do that calculation for you.
"But if you say, well I don't know how that fairy would arise then I can't tell you the answer. That is the situation that we are in with the origin of life -- we don't know what did it, we can't put a number to it."
Regardless of all the unanswered questions, Davies says that such research is vitally important. Trying to determine if life is sustainable in other planets is part of the 'lifeboat answer' that could give human culture the chance to survive, should Earth be unable to support humanity in the distant future.
"There is a distinct possibility humanity will be wiped out by some mega catastrophe," he said.
"It could be a killer plague, it could be an asteroid strike it could be nuclear war, it could be any number of reasons why humans would vanish from the face of the Earth.
"If there is a permanent human presence beyond there, the flame of humanity and our culture and so on will be kept alive."
Paul Davies will part of a panel at the event titled Life on Mars: NASA's 2020 Rover Mission, on August 17 at the Sydney Opera House.Suggest a correction