Are we alone in the universe? That’s a question humans have pondered throughout the ages. That’s also a question that may find an answer sooner than you think. With the help of modern technology and mathematical estimates, scientists predict that within the next 20–40 years we will discover intelligent life in our own galaxy!
But how does a prediction like this work?
First, scientists use an estimate of how many planets are home to intelligent life, using the Drake Equation. Frank Drake, who helped to found SETI (Search for Extra-Terrestrial Intelligence) developed the Drake Equation (illustrated below) which predicts the number of intelligent life-bearing planets in our galaxy.
The Drake Equation uses a combination of estimates to calculate the approximate number of civilizations in the Milky Way that have detectable communication in the form of electromagnetic radiation. This could be anything from X-rays to radio waves to visible light. It turns out, that for every 1 million stars, the Drake Equation suggests that at least one star will have a planet orbiting it that harbours intelligent life.
But how likely is it that we would discover such a planet in our lifetime? You may be surprised to learn that it’s very likely. The Kepler Space Telescope searches a tiny fraction of our galaxy for planets that lie within what we call the "Goldilocks zone"—not too hot, not too cold, but just right.
The portion of the Milky Way that the Kepler Space Telescope covers is so small that if you hold a dime up to the sky, you can cover it up. However, within this small section of sky, 150,000 stars have been scanned so far and around 4,000 planets have been discovered with conditions suitable for life—liquid water, a non-hostile atmosphere and temperature, and a size varying from slightly larger than Jupiter to smaller than Earth. Assuming that the Kepler Space Telescope continues to scan at this rate, it will take about 20 years to examine one million stars—the number required by the Drake Equation to find intelligent life.
However, there are some things we are not taking into account, like how likely we are to discover some form of life along the way (not just intelligent life) or the increasing rate at which technology is progressing. We could, for example, create amazing new telescopes within the next 20 years that speed up the scanning process.
The best part about the search for life in space is…you can help too! SETI has a computer program called SETI@home which you can download onto your PC. It will analyse data from distant star systems while your computer would otherwise be idle; you can even set it as your screen saver.
When we do find alien life, it will probably be very different from us! Even on Earth, the diversity of conditions that support life is staggering. There are microbes that live: in the 400oC heat of hydrothermal vents at the bottom of the ocean, on the surface of radioactive waste, and deep within the Antarctic ice sheets.
Life is diverse and the possibilities are endless. The universe is a continuously expanding, vast and enriched environment. Our Milky Way galaxy is home to roughly 100 billion stars, and ours is just one of nearly 100 billion galaxies. Doesn’t it seem extremely unlikely that we are the only form of life that exists? What does it mean for us if we're not? Luckily, you will probably be around to find out!