The Drake Equation & Fermi's Paradox

Are Humans the only intelligent life in the universe?

If so, why? If not, how likely is it that other intelligent beings would exist, and where the hell is everyone?!? These are examples of the questions being asked by scientists at the SETI Institute as they search the cosmos for signs for extraterrestrial intelligence.

^{Image Source: Pixabay}

I usually try to stick with established science fact on this series, though I've meandered into the realm of theory more than once. In this edition of Super Cool Science S#!t, let's explore the idea of extraterrestrial life, how we would go about determining the likelihood of its existence, and a few theories as to why we still don't have solid empirical evidence despite a cross-cultural phenomenon of unexplainable sightings.

Fermi's Paradox isn't so much a paradox as a conundrum.

^{Image Credit: Smithsonian Institution Archives}

Enrico Fermi wasn't the first to pose the question he did in the summer of 1950, but it became a prolific moment for the scientific community none-the-less. Fermi, an italian-american physicist, and a few of his colleagues working at the Los Alamos National Laboratory were walking to lunch and discussing a recent string of UFO sighting.

During lunch and seemingly out of nowhere, Fermi exclaimed something along the lines of "Where is everybody!?" and is peers all seemed to know he was speaking of extraterrestrials. He went on to explain that thinking about the probability of the number of earth-like planets, the chance of life and technology existing on any one of them, and stated that extraterrestrials almost certainly should have visited us long before, but there still exists no evidence to prove such a hypothesis.

Possible Explanations to Fermi's Paradox

We can't honestly pretend to understand what life on another planet may look like, how it evolves, or what challenges it may face, but many people much smarter than I have proposed dozens of potential explanations for the apparent lack of intelligent extraterrestrial life. A few of those hypothesis include:

- Intelligent life or technology is incredibly rare.

Probably the simplest explanation would be that the conditions required for life to begin at all are so incredibly rare that complex life which would develop "intelligence" could be unique to Earth. Either there just aren't many, or we're genuinely the only beings that have evolved to our level. It's also possible that any intelligent life that might exist out there just hasn't developed the types of communication we're able to detect.

- The nature of intelligent life is to destroy itself or others.

I personally believe it's a bit naive or arrogant to think aliens would behave the way we do, but it's been proposed that it could be completely natural for intelligent life to dominate those around them, and that the rise of technology creates an exponentially growing chance of self-destruction.

- Aliens exist, but refuse to communicate with us.

What if we're the ones who aren't advanced enough? What if there's more to all these UFO sightings, and aliens treat Earth like a zoo of sorts, observing our evolution waiting for the right time to finally communicate.

- Alien life just may be too alien.

This is probably my favorite explanation. We only have one subject planet in our study of how life evolves. We have no clue how life on another planet look, behave, or communicate. There's not much reason to believe another intelligent being would be anything like anything that's evolved here. It's completely possible that we're the "weird" life that evolved differently from the rest, and they can all communicate in a way we couldn't comprehend...

The Drake Equation

A decade after that conversation between Fermi and his colleagues, Frank Drake conducted the very first search for extraterrestrial radio sources, dubbed Project Ozma. Using an 85 foot radio telescope at the National Radio Astronomy Observatory, Green Bank, Drake examined two nearby Sun-like stars over the course of a few months' time, but unfortunately didn't detect any radio signals.

One year later, Drake would host the first meeting of SETI, or the Search for ExtraTerrestrial Intelligence. The topic of conversation for this meeting would become one of the most famous scientific formulas in history.

As I planned the meeting, I realized a few day[s] ahead of time we needed an agenda. And so I wrote down all the things you needed to know to predict how hard it's going to be to detect extraterrestrial life. And looking at them it became pretty evident that if you multiplied all these together, you got a number, N, which is the number of detectable civilizations in our galaxy. This was aimed at the radio search, and not to search for primordial or primitive life forms.

—Frank Drake

^{Image Credit: SETI Institute}

N = R_*f_pn_ef_lf_if_cL

This beautifully simple formula is a probabilistic argument used to determine the number (N) of communicative extraterrestrial civilizations that might exist in our galaxy, and takes into account a number of variables that would go into such a calculation;

R_* represents the average rate of star formation
f_p represents the number of those stars that have planets
n_e represents the number of planets where life could potentially begin
f_l represents the average number of planets that actually develop life at some point
f_i represents the average number of life-bearing planets where intelligent life evolves
f_c represents the average number of planets with civilizations that develop a detectable means of communication
L represents the average length of time those civilizations would actually transmit that detectable signal

There's just one problem...

While we can logically and concisely understand the variables that would go into such a calculation, we don't have enough data to accurately solve it. We've only recently begun discovering exoplanets.

We have no idea how many of them have or even could house life at all. We have no idea what fraction of alien species develop civilizations or transmit signals through space that we're able to detect. We genuinely don't have a large enough study size to confidently find an answer to Drake's Equation.

However...

That hasn't stopped a few people from trying to do so anyway, including Drake and his colleagues. With educated guesses for each variable, they determined there could roughly be 1000 to 100,000,000 civilizations spread out across the hundreds of billions of stars in our little Milky Way galaxy.

The Drake Equation & Fermi's Paradox | Super Cool Science S#!t #26

The Drake Equation & Fermi's Paradox

Are Humans the only intelligent life in the universe?