Do Aliens Exist?

Are we alone? Or is there life on other planets? Ask Science discusses the two major breakthroughs in the search for extraterrestrial life making headlines this week.

Sabrina Stierwalt, PhD
5-minute read
Episode #156

The Search for Intelligent Life

Besides the huge progress made over the last two decades in the search for habitable planets, the search for intelligent life is a much more difficult task. First off, the distances to other worlds are prohibitive. Humans have never traveled farther than the Moon! Even our space probes are lost once they leave the outer reaches of our solar system, and the nearest star is a whopping four light years further away. Second, even if we did have the resources to reach out to a particular star, in hopes that it hosts a life-bearing planet, which star would we pick? Our Milky Way galaxy is home to at least 100 billion stars!

Luckily there is a way to communicate across the vastness of space without the need for a human space traveler or even a probe: radio waves. A dead giveaway that there is intelligent life here on Earth (at least from an outsider’s perspective) are the nonstop radio emissions we send out into space for everything from air traffic control to satellite communications.

Now these radio emissions aren’t sent so they will be detected by aliens in the far reaches of our galaxy so someone would have to be listening really hard to find them. We did, however, once use the large Arecibo radio dish nestled in the Puerto Rican jungle to send out an encoded message explaining what life is like on Earth for anyone who might be listening. You can have a look at the message and see if you can decode what each line is meant to represent! So far, no one has returned our call.

The goal of programs like the Search for Extraterrestrial Life (SETI) and Yuri Milner’s Breakthrough Listen Initiative is to search for other solar systems for planets emitting such signals. As outlined by the astronomer Frank Drake in his famous Drake Equation, the chances of detecting such a foreign signal depend on a lot of poorly constrained factors. How many stars do we have the resources to spend time observing? How many of those could have habitable planets? How many of those planets have been around long enough and have the unique conditions necessary to develop intelligent life? How many of those civilizations use radio waves to communicate and have sent out a signal for us to detect?

The task seems daunting, but the reward is so huge and potentially life-changing for all of us Earthlings, that many see it as worth the effort.

How Can You Help?

Searching a range of radio frequencies for signals amongst the Milky Way’s 100-200 billion stars is sometimes referred to as looking for a signal in the “cosmic haystack.” With the new funds provided by Milner, both SETI and Breakthrough Listen will be able to drastically increase the size and scope of their searches. This effort will result in, as you may have guessed, an enormous amount of data. Thus, both are looking to citizen scientists (that’s you!) to get things done.

Three million users already participate in the SETI@home project which works as a screensaver that processes SETI data when your computer would otherwise be idle. The Breakthrough Listen Initiative plans to use open source software called BOINC to do a similar task. BOINC is already tackling many different scientific problems from climate change to pulsar searches by using your smartphone or tablet to process data. The app only runs while your device is plugged in and fully charged so it doesn’t run down your battery, and it does not contribute to your data rate.

There are a lot of factors working against the search for extraterrestrial life, most significantly large interstellar distances. But getting involved in the search takes minimal effort, and what if your phone finds the first ever message from ET?

 “This is the biggest question. We should be listening.” – Yuri Milner

Until next time, this is Sabrina Stierwalt with Ask Science’s Quick and Dirty Tips for helping you make sense of science. You can become a fan of Ask Science on Facebook or follow me on Twitter, where I’m @QDTeinstein. If you have a question that you’d like to see on a future episode, send me an email at everydayeinstein@quickanddirtytips.com.

Planet image courtesy of nasa.gov and Shutterstock.


Please note that archive episodes of this podcast may include references to Ask Science. Rights of Albert Einstein are used with permission of The Hebrew University of Jerusalem. Represented exclusively by Greenlight.

About the Author

Sabrina Stierwalt, PhD

Dr Sabrina Stierwalt earned a Ph.D. in Astronomy & Astrophysics from Cornell University and is now a Professor of Physics at Occidental College.