The Milky Way galaxy is home to about 100 billion stars, and maybe even more planets. With so many planets, it seems likely that some might host intelligent life. And if you’ve read or seen the Netflix series 3 Body Problem, you might be wondering: why haven’t we tried to contact any alien lifeforms? The short answer is, we’ve tried.
The Drake Equation
In 1961, Dr. Frank Drake, a radio astronomer, formulated the Drake Equation to estimate the number of advanced civilizations in the galaxy that we could conceivably communicate with. It looks like:
Here’s what it means: N is the number of planets with advanced civilizations in the Milky Way. This, according to Drake, is proportional to the average rate that a star forms in the galaxy (R*), the likelihood that those stars have planets orbiting them (fP), and the average number of those planets that potentially support life (ne·fl)
According to Dr. Drake and other astronomy researchers, these factors alone bring the total to about 100 million planets. But even with today’s technology, this value is tricky to pin down with any good precision. The computation only gives way to even more conjecture as you include the next few parameters.
fi and fC are the fractions of planets with life that actually develop intelligence and create detectable signals. The last parameter, L, is how long it takes for an intelligent alien race to start sending these signals out into the void of space. These last three parameters are entirely based on what we’ve seen with the civilizations on Earth, which isn’t a very good sample size.
With how much guesswork is involved, the solution to the Drake equation can range between 1 (i.e. Earthlings are the only creatures intentionally sending out signals) to 15.6 million planets. Despite the uncertainty, Drake decided he still had to try to communicate with one.
Source- Pixabay
Seeking Signals from the Void
In 1961, physicists Giuseppe Cocconi and Philip Morrison decided that 1420 megahertz was the most logical radio frequency for communicating with extraterrestrial life.
This frequency, known as the Hydrogen line, is emitted by hydrogen when its electron changes quantum states. Since hydrogen is the most abundant element in the galaxy, and the hydrogen line can penetrate through space dust rather easily, any reasonably intelligent creature would think to use it.
Dr. Drake was one such intelligent creature, and he tuned into the hydrogen line for months in 1960, using a radio telescope to look for signs of other intelligent life beyond our solar system.
Drake’s initial search turned up blank, but he and his hunt for alien communication didn’t stop. In 1961, he held the first conference for the search for extraterrestrial intelligence (SETI) which aimed to assign values to the parameters in the Drake equation. As astronomical technologies advance, these values get better and better.
The Modern Search for Extra-Terrestrial Intelligence: A Resurgence of Hope
Fifteen years after Drake’s search, two former NASA employees founded the SETI Institute which aimed to continue the search for extraterrestrial signs. Frank Drake served as one of the institute’s first trustees.
Radio telescopes are used to detect signals. Source – Pixabay
Today, researchers at the SETI Institute have figured out how to expand the search for distinct alien signs. Now, rather than sticking to the hydrogen line, they analyze 100 billion different frequencies at a time.
And the institute is still working on ways to improve.
One idea they have is to someday build a communication tower on the dark side of the moon. This will let them probe space for signals within the radio frequency range (1 Hz – 3000 GHz), which is a dead zone here on Earth due to radio pollution from our own technology.
Are We Alone? Drake’s Final Verdict
In 2016, researchers at the University of Rochester in New York revisited the Drake Equation. Given that we’ve discovered millions of potentially suitable planets for life since the inception of the Drake equation, they sought to answer the question of how likely it is that there is or was other life out there.
They found that the chances that no other life evolved would have to be extremely low – 1 in 10 billion trillion – for Earth to be the only evolved planet in the history of the galaxy.
Although we haven’t found any other signs of intelligent life yet, there is still plenty of excitement among researchers to pursue it. Frank Drake passed away in 2022, but before then, he settled on an educated guess for a solution to his equation: 10,000 planets with intelligent life in the Milky Way. Do you think we’ll be hearing from any of them soon?
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