For Science!Astronomer Reveals The Truth Behind Civilization: Beyond Earth's ExoplanetsFor Science! - RSS 2.0
Why is it important to find exoplanets?
For the average person, the existence or non-existence of other planets will have no effect on day-to-day life - not for a long time, at least. So I asked Dr. Kane why his research is important to humanity.
"...I would hazard a guess that most planets that are habitable are inhabited - but not by advanced life."
"It's a perfectly reasonable question," he admits, "because there are so many distractions these days that occupy our time. But I always try and remember the writings of people from the past few hundred years - these people were talking about other planets with absolutely no data to back up their claims. Even as far back as 300 BC, the philosopher Epicurus was talking about the 'plurality of worlds.' It was a very philosophical exercise, but it was always something which captured the imagination.
"I think it's extremely important for human civilization to know that we are not just a single oasis in a vast universe, but that there are other potential homes out there. And now that we're at that point when we finally have the technology to answer these questions that people have been asking for a long time, it's an enormous threshold in human knowledge to go from not knowing if there's another place like the Earth, to knowing that there is."
Laughing, Dr. Kane added, "And of course the next question is, 'How do we get there?'"
Ultimately, there really is no practical reason for the importance of searching for exoplanets for the modern everyman - but the inspirational reasons are paramount. "In my opinion," says Dr. Kane, "discovering planets around other stars is one of the most important research endeavours of the modern age. It's something which is much larger than ourselves and answers some very fundamental questions about our place in the universe."
The Drake Equation: What are the odds of finding intelligent life?
Given there may be so many habitable planets out there, we then tend to wonder how many alien civilizations may exist in our universe. In 1961, astronomer and SETI founder Frank Drake came up with a formula to estimate the number of intelligent civilizations that may exist in the Milky Way. It was never meant to be a means at arriving at a firm number, but was rather a probabilistic argument intended to provoke thought and discussion.
SIDEBAR: The Drake Equation:
N = the number of civilizations in our galaxy with which radio-communication might be possible
R* = the average rate of star formation in our galaxy
fp = the fraction of the stars in our galaxy that are orbited by planets
ne = for every star that has planets, the average number of planets it has that can potentially support life
fl = the fraction of planets that could support life that actually go on to develop life
fi = the fraction of planets with life that develop intelligent life (i.e. civilizations)
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space (i.e. radio waves)
L = how long such a civilization releases detectable signals into space
The equation's parameters begin with things that we can estimate based on observation and information, such as the average rate of star formation in our galaxy, and become increasingly unknown or unknowable the deeper into the equation we get. But Dr. Kane believes that as we move toward the later parameters that revolve around intelligent life, the numbers will start to drop to zero. "It seems like all stars have planets, and most of them probably have planets with liquid water on their surface," he says. "And I would hazard a guess that most planets that are habitable are inhabited - but not by advanced life."
"I'm not one of those people that says, 'Well, there are so many planets out there; of course life is common!'" Dr. Kane adds. "We can actually quantify that better because we know that life on Earth started extremely quickly." He points to evidence that life arose on Earth as far back as four billion years ago - relatively soon after the planet's formation. He points to the abundance of hydrogen and oxygen in our solar system (the first and third most abundant elements, respectively) as evidence that water should be extremely common on planets. "So I suspect that there's a lot of life out there," he says.
The Fermi Paradox: Where is everybody?
While life may be common, having life evolve into something intelligent is another issue entirely. In 1950, physicist Enrico Fermi summed up in one question the paradox that arises when we consider just how common life may be in our universe: where is everybody?
"...it's an enormous threshold in human knowledge to go from not knowing if there's another place like the Earth, to knowing that there is."
If life is everywhere, why have no civilizations made contact with us? Why haven't we detected radio signals? Why haven't we seen any signs of colonization?
Dr. Kane believes that the solution to this paradox is that evolution rarely leads to intelligent life. "If you look at the history of life on Earth, we see all kinds of adaptations to the environment. Evolution doesn't necessarily favor intelligence - it favors adaptation and reproduction." As long as a creature is able to survive in its environment and give rise to viable offspring that will continue to pass on its genetic code, it is evolutionarily successful. "It's not necessarily the case that intelligence is the peak of this evolutionary pyramid."
The sobering reality is that it was dumb luck that allowed for the evolution of intelligent life in humans. As Dr. Kane puts it, "If the Earth hadn't been struck by a giant impactor 66 million years ago, we'd all still be speaking dinosaur, right?"