There are a least a hundred billion stars in the Milky Way, our home galaxy. And there could be trillions of planets! That leaves a lot of potential real estate for extraterrestrials.
Let's optimistically assume that we'll one day find aliens. How might that happen? Maybe it will be like in the movies! They'll visit Earth with their faster-than-light starships, hopefully coming in peace, like the Vulcans from Star Trek or the squid-like beings in Arrival.
Or maybe first contact will come in the form of a message or media broadcast sent from deep space, picked up by one of humanity's humongous radio telescopes.
Perhaps we'll uncover aliens closer to home? We might dig up microbes on Mars, find floating bacteria in the clouds of Venus, or discover deep-dwelling life at the bottom of Europa's oceans.
Any of these scenarios would provide a climactic answer to the nagging question of whether we're alone in the universe. Sadly, however, as Michael L. Wong, an astrobiologist and planetary scientist with the Carnegie Institution for Science, told RealClearScience, we're unlikely to enjoy such a satisfying end.
"Initial claims of alien life will not be certain. There will be debates. It could take decades to actually decide if it’s life," he said.
Barring an alien visitation here on Earth or a clear, jackpot discovery by a robotic rover within our solar system, the first "discovery" of life will likely be made by astronomers. With telescopes gazing into the far reaches of the galaxy, scientists might spot "technosignatures," signs of alien technology, or "biosignatures," signs of alien life. But these faraway detections will assuredly leave room for doubt and skepticism.
Wong's best hope, he said, is that we’ll find a huge swath of exoplanets that have strong life signatures, so we can be relatively certain that at least one of them hosts extraterrestrials. We would be leveraging the power of statistics to make one of the most consequential deductions in human history. It might not be the Hollywood ending to the search for aliens we've all been hoping for, but it will be groundbreaking nonetheless.
