Just for a moment, imagine a universe teeming with life where humans are not the only intelligent beings around. What might these alien races look like? Could we communicate with them or even recognize their intelligence? Would they look at us as violent and primitive beings, deciding not to bother with us? Or might they enrich our world with unimaginable scientific knowledge? Alternatively, an encounter could have a more destructive outcome. But relax, it’s just make-believe. Or is it?
Welcome to the Milky Way, our cosmic home. Our sun is just one of hundreds of billions of stars in this galaxy. Now think of not just one but billions of galaxies, and you have the universe. It’s too vast to measure in miles, so we use light years - the distance light travels in one year at about 186,000 miles per second. One light year equals nearly six trillion miles! Light takes 100,000 years just to cross our galaxy, meaning when we look at the stars, we are looking back in time, seeing events that occurred millions, even billions of years ago, before Earth existed.
Given this vastness, the likelihood that we’re the only intelligent beings seems bizarre. Scientists are making astonishing discoveries suggesting that we are not alone. In 1995, they found a planet 40 light years away, named 51 Peg B, shaking the scientific world. Since then, over a hundred other planets have been discovered. With rapidly advancing telescopes and computers, we’ve only begun to scratch the universe’s surface.
We aim to find out why scientists are confident we might not be alone—a discovery possible between 2020 and 2025. Deborah Fischer, for example, is a planet hunter from San Francisco State University. Thanks to her and others, we now know of over 130 planets outside our solar system. Fischer watches distant stars for gravitational wobbles caused by orbiting planets, a remarkable achievement when considering the scale and distance involved.
The search for life has stringent criteria; life seems more likely on smaller, rocky planets that can maintain a solid surface and an atmosphere. Liquid water, essential for life as we know it, exists in a narrow Goldilocks zone – not too hot and not too cold.
A landmark discovery came in June 2004: the smallest planet found outside our solar system, just 14 times the size of Earth with a potentially rocky surface, 50 light years away. Future missions like the Kepler Observatory are expected to find even more Earth-sized planets by detecting subtle dips in starlight as planets pass in front of their stars.
For over 20 years, the SETI Institute in California has led the hunt for extraterrestrial intelligence by listening to radio signals – our cosmic whispers. Radio signals, though basic, are a powerful form of communication, traveling at the speed of light. The challenge lies in how long it takes these signals to travel; a message from the other side of our galaxy would take 100,000 years to reach us.
Other methods of searching involve looking for optical signals through powerful lasers. Scientists like Dan Werthimer from Berkeley scan for these brief, bright flashes, potentially signaling intelligent life. Although millions of stars have been scanned, there’s yet to be any conclusive evidence.
Life on other worlds seems plausible, especially given recent discoveries of extremophiles – organisms that thrive in Earth’s harshest conditions, from deep caves eating rock to microbes living in toxic, high-temperature, or highly-saline environments like Mono Lake in California.
Places like Titan, Saturn’s largest moon with its dense atmosphere, and Europa, Jupiter’s icy moon possibly concealing a liquid ocean, are next targets for space exploration and likely candidates for potential life. Discoveries of water signatures on Mars further intensify the hope of finding microbial life.
The search pushes forward with advancements like the Allen Telescope Array, set to scan millions of stars in the next two decades, hoping to hear that elusive signal from intelligent beings. Scientists like Seth Shostak of the SETI Institute predict we will know we are not alone by 2025.
How will life change if we ever confirm extraterrestrial intelligence? While some, like Professor Stephen Hawking, fear potential destruction, others believe contact could be profoundly transformative, reshaping our understanding of the universe and our place within it.
Eyes and ears on the cosmos, humanity ventures ever deeper, driven by timeless curiosity to answer one of the most fundamental questions: Are we alone? Time, and our relentless drive for knowledge, will tell.