The Fermi Paradox
In 1950, Enrico Fermi and his buddies were sitting around during lunchtime chatting it up. They were interesting guys, being physicists, and their conversations often took wild turns. Fermi, the creator of the first nuclear reactor, didn’t just think about how to power the world. Like his friends, he considered the world. He asked things like “Where did we come from?” and “Where are we going?”. Questions like this are on the forefront of many of our top scientist’s minds.
Back in 1950, it was certainly on Enrico Fermi’s mind. We know that because he posed one of the most fascinating questions that scientists still debate to this day. The question is simple. Yet it asks so much of us. It yearns for so much information that we simply do not have. His question was:
“Where is everybody?”
They weren’t playing hide-and-seek. Nobody had accidently hit the light switch to the break room. Fermi was talking about aliens. He figured that if the universe is so big and filled with so much stuff, shouldn’t we have run into some other intelligent form of life by now? Shouldn’t we have gotten a sign that we humans are not the only one’s who can send crafts out into the vacuum of space?
Mind you, this was 1950. Astrophysicists in these days were less aware of what lies beyond our planet. The Sputnik 1, the first probe in space, wasn’t set to launch until 1957. No helicopters were on Mars as they are now. No probes had been sent to Jupiter. No man had set foot on the Moon. In fact, no man had even been in space yet. Yuri Gargarin, the first man in space, wouldn’t get there for another 11 years.
Yet, Fermi was confident that the Universe was a massive and diverse place. Despite his lack of knowledge, he knew that the probability should be high that intelligent life exists beyond our planet. He figured that with modest rocket technology, if someone was out there, they should be here by now.
Bold words. But he had a point.
Now it is 2021. We know a bit more about the world around us. To understand how probable it is that intelligent life exists beyond Earth, we must determine the probability that intelligent life can even be created in the first place.
And that is going to take some examination.
Where Did We Come from?
Unless you have the processing power of the computer created by Edmond Kirsch, fictional billionaire philanthropist from the Dan Brown novel Origin, you might be wondering: Where did we come from?
We currently know where we are. We are on Earth. Earth, it turns out, is pretty cool. We have a sun to keep us warm but an atmosphere to keep us safe from it’s UV rays. We have a moon that is big enough to create tides which circulate nutrients in our oceans, making life there possible. We have Jupiter to protect us from the many nefarious space bits that could cause our demise. All in all, it’s a good place to be.
But how did we get here in the first place?
Our Earth is 4 billion, 543 million years old. According to scientists much smarter than I, they have determined that rocky planets such as ours could take about 500 million years to cool off. After this time, it is possible that life can begin to develop. Our oldest fossils are dated back to 3.5 billion years ago. We will move forward with the assumption that life began on Earth at that time. However, this is a big assumption. What we know is that at least 3.5 billion years ago life existed here on our special planet. But it may have began sooner.
What is life, exactly? At the fundamental level, it is organic matter (matter containing the atom carbon) that can replicate. In 1953, shortly after Mr. Fermi asked the famous question that sparked much controversy, scientists James Watson and Harold Crick thought they had found something amazing. They stole research from Rosalind Franklin that hinted at a breakthrough in, well, life. After observing her work and drawing further conclusions, Watson and Crick had discovered DNA. They realized its function as the instructions on how to make life as we know it. They went into bars and pubs shouting at the patrons about how they had figured it out. They figured out the key to life.
How DNA came to be is still a mystery. It's something we are actively trying to recreate in our labs. That same year, Stanley Miller, observed by Harold Urey, devised the famous Miller-Urey experiment. With many tubes, flasks, thingamajigs, and doohickeys, Stanley Miller created what he believed was the components of an early Earth: water, carbon dioxide, methane, and ammonia. He used electrical sparks to simulate lightning in an early Earth atmosphere. The goal was to see what would come of the primeval soup over time as energy interacted with these elements. What Miller received at the end of a week of sending sparks into some early Earth elements was fascinating:
A brown liquid.
This wasn’t just any brown liquid, though. Within it were amino acids. Amino acids are the building blocks for proteins. Proteins are the fundamental building blocks that DNA uses to create body parts, hemoglobin, and other life stuff. We didn’t know that at the time because Watson and Crick had just found out that DNA existed. But Miller knew he had learned something valuable. He had created organic molecules, that we know are essential for life, out of seemingly nothingness.
From this experiment, the term abiogenesis was used more often to discuss the most probable way that life began: organic molecules being created from the atoms that existed on early Earth. As we learned more about Earth, we soon came to realize that Miller’s initial experiment was flawed. We learned that ammonia and methane were most likely not present in early Earth as they were in his experiment. We had to go back to the drawing board.
Abiogenesis is not the only theory for the Origin of Life. In 1969, the year Neil Armstrong and Buzz Aldrin landed on the moon, an amazing discovery was made that pointed the Origin of Life conversation in another direction. A meteorite name Murchison fell in Australia. Upon examination, eighty amino acids, twenty of which are essential for life, were identified as components of the space faring rock. The Origin of Life scientists then began to ask: Did life arrive here from outer space?
Despite this new hypothesis that had gained a lot more traction after Murchison, Miller had not given up on his original abiogenesis hypothesis. He tried his experiment again in 1983 with what we believed were the correct early Earth elements. However, his redo was unsuccessful at producing the amino acids observed in the first experiment. Miller figured his initial findings were a fluke. So did the rest of the scientific community.
That was until 2007, when chemist Jeffrey Bada ran another version of the Miller-Urey spark discharge experiment. Bada realized that Miller’s 1983 experiment was yielding nitrites. These nitrites were destroying the amino acids upon formation. Bada knew that primitive Earth would had contained iron and carbonate minerals. These components would neutralize nitrites and maybe, just maybe confirm Miller’s original hypothesis.
He completed the experiment with a new result. He got the same watery, amino-less liquid that Miller got in 1983. Except this time there were amino acids. And a lot of them.
Isn’t that great? Aren’t you excited that we know that the building blocks of the building blocks of life can be created in a simulated early Earth environment with test tubes in a lab? I am too. Except for the part where DNA isn’t made of proteins. It isn’t even made of amino acids.
DNA is made of the sugar deoxyribose (and some other stuff). The transmitter for DNA, RNA, is made of the sugar ribose. We have yet to devise an experiment that simulates early Earth that also produces these molecules. All we can do is create the building blocks for proteins, which need DNA and RNA to be useful.
That means that we are missing something crucial. We are missing the one thing that would unlock many doors of our understanding of where we came from: the molecule that is the origin of life.
Oxford Professor Richard Dawkins wrote a monumental book called “The Selfish Gene” in 1976. This was in between Miller’s experiments. It was also before people had debunked the original Miller-Urey experiment. Dawkins even references the experiment’s success. In the book, he also coined the term ‘meme’ that we all should be quite familiar with today. That’s not relevant information. It’s just fun.
In this book, Dawkins discussed an idea called the ‘Replicator’. Dawkins was aware of our insufficient evidence of the fundamental element of life. That being said, it is accepted that, since life replicates, the fundamental element of life must be a thing that replicates. So, what is that thing?
Origin of Life scientists find themselves in between a few theories. Some find themselves in the RNA-First camp, believing that RNA is the first replicator. Others, find themselves in the pre-RNA camp, convinced that something might be able to replicate before RNA needs to form. The most moving theory to date is the “small-molecule paradigm.” To save you some boredom, it has no evidence backing its claims (yet).
The reality of the situation is we don’t know a lot when it comes to the Origin of Life. And here I am trying to speculate that we are not alone in the Universe. To my credit, we do know one thing, that organic molecules like amino acids can be created from atoms in an early Earth environment. We also know that the Earth is old. It's 4.5 billion years old. It’s one-third of the age of the Universe itself. Miller ran his spark discharge experiment for one week. That’s like, a lot less than 4.5 billion years.
Who knows what could happen in that time?
How Much Opportunity Is There for Life to Develop?
Enrico Fermi knew that the universe was big. He also knew that it was filled with a whole bunch of stuff. Some of this stuff might harbor intelligent life. But the question is, how much stuff is there?
When the Fermi Paradox was first postulated, Enrico and the science community at large hadn’t even found one planet outside of our solar system. Yet, they knew space was most likely filled with them. Today, we have found over 3,000 planets outside of our solar system. And this is just what we have found since 1995 when the first exoplanet (planet outside of our solar system) was found. Many of them are rocky, like our Earth. Many of them are within the habitable zone of a familiar looking star, which is a possible indicator that life can exist there. To be specific, 53 planets of the confirmed 3,000 have signs of habitability. That’s 1.8%. That might not seem like a lot when represented as a percentage. But what if we multiplied that across the entire Milky Way galaxy?
Each star in our Milk Way galaxy is expected to have 1.6 planets swirling around it. With around 100 billion (to a possible 400 billion) stars, that means there are a lot of planets out there. If we take the 160 billion total planets and multiply it by our 1.8% figure, how many of these planets may be habitable?
The answer is 2.88 billion potentially habitable planets. To put that into perspective, if you were to count to 1 billion starting now, it would take you 95.1 years. And that’s just how many habitable planets might be within our own galaxy.
But the Milky Way isn’t the only galaxy. The known Universe is 92 billion lightyears in diameter. The Hubble telescopes imaging has estimated that within the unfathomable volume of the Universe there are possibly 2 trillion galaxies. If we assume that each galaxy on average has the same number of stars and planets orbiting their stars as ours, how many habitable planets may there be?
5.76x10^21. In normal people speak, that is 5,760,000,000,000,000,000,000. Or 5.76 sextillion. Or you counting for 548 billion years. Or you counting for 39,636 Universe lifetimes. I would argue that’s enough possible habitable planets to warrant some speculation.
The numbers I have stated are not within our understanding. They are also probably off, high or low, from reality by large orders of magnitude. But one could argue that the even if I’m off by a lot, the number of possible habitable planet’s in the known Universe is still staggering. Enrico Fermi had a point.
Where is everybody?
How Much Time Does It Take for Intelligent Life to Form?
The key word here is ‘intelligent’. There are 1.5 mm animals called tardigrades that can survive in the vacuum of space, live to tell the tale, inseminate their partner, and have tiny tardigrade offspring afterwards. However, tardigrades did not invent telescopes, spacecraft, and pizza. And we, as pizza-inventing homo sapiens, would not survive in such harsh conditions. We must again assume, on the little information we have about life, that the planet must be a rocky and habitable place for smart weaklings like us to evolve.
From the little we know about the Origin of Life, homo sapiens possibly took 3.5 billion years to develop on Earth after the first lifeform existed on Earth. This is if we go with any one of the replicator-type hypotheses outlined earlier. I also mentioned that scientists claim a rocky planet cools down enough and forms an atmosphere suitable for harboring life after about 500 million years. Those being the knowns (or at least the good-enoughs), then we can hypothesize that intelligent life requires, at most, 4 billion years to develop on a rocky and habitable planet.
In a less habitable world where there is no Jupiter to protect the rocky planet from bombardment and life must keep re-evolving to more complex states, it could take longer. In more ideal conditions where a meteor didn’t wipe out almost the entire living population and a Cambrian explosion-type event happened sooner, it could take less.
I’d say that in a Universe with 5.76 sextillion possibly habitable planets where intelligent life takes, at most, less than one-third of the age of the Universe to develop, there should be more intelligent life out there.
We might not even have to look that far. Life might be right next door.
Do We Know That Life Exists Beyond Earth?
We all know of Elon Musk’s obsession with Mars. Some people on Twitter might disagree with him that space is worth exploring. However, we are humans. We explore. It’s kind of our thing. From the expanses beyond the continent of Africa to setting foot on the Moon, people are obsessed with finding out what is around us. And Mars is a fascinating place to look for many reasons.
Mars is the fourth planet from the Sun. It’s just beyond Earth. It’s within the habitable zone of the Sun. The temperatures there are reasonable. In the summer months in the lower latitudes, the surface temperature may even get to about 70 degrees Fahrenheit. Although the average is around -81 degrees Fahrenheit.
Mars orbits the Sun in 687 Earth days. That was a random piece of information. What’s not is the fact that the Mars Sol (day) is only 40 minutes longer than an Earth day. That means none of the surfaces are exposed to the sun for long durations which could cause temperatures beyond habitability. There is even water there right now. We know there is some frozen in the polar ice caps. There may even be some liquid water beneath the surface.
When we observe the surface of Mars, we see a surface that once had branching streams, flowing rivers, basins, and deltas from flowing liquid. We even see possible lake formations that were created by rainstorms flooding dents in the planet’s surface.
If liquid water was present, Mars must have had a thick atmosphere capable of maintaining liquid water at Martian temperatures and pressures before the atmosphere was lost to space. Mars is also abundant in carbon, which we know from the spark discharge experiments are key to forming amino acids. Amino acids we know are key to building proteins. Proteins we know are key to building life.
That means if abiogenesis is possible, it probably happened on Mars given the signs and potential former conditions. However, if intelligent life existed on the planet, it is either long gone, migrated here to Earth and became us, or went somewhere else and there are no signs of it. However, if we can find signs of life on Mars, our hope for finding out the probability that there is intelligent life out there goes up.
Mars is fun to talk about because it is so obvious. NASA and Elon have set their sights on the planet and plan to put boots on the ground by the 2030s. As great as Mars is, we must not forget about another one of our cosmic neighbors, Venus.
Venus is the rocky planet before us in the order of the solar system. Right now, it sucks. You really wouldn’t want to go there. Even if you were double-dog-dared to, I would suggest you didn’t. It has a carbon dioxide atmosphere ninety times as thick as Earth’s. It’s surface temperatures reach up to 864 degrees Fahrenheit. And there is almost no water vapor to cool you off. Not fun.
But models suggest that it once may have been habitable. For 2 billion years, Venus may have had a shallow liquid-water ocean and habitable surface temperatures. This could have been when the Sun was 30% dimmer than it is now.
Unfortunately, we can’t see the surface of Venus easily. Its thick carbon dioxide atmosphere get in the way. Ten Soviet probes have landed on the yellow planet. The pictures they have sent back of it show a rocky surface with minimal visibility. But it once might have been home to an alien Marriott hotel chain. We really don’t know.
With the potential for life seemingly all around us, does intelligent life exist? And if so, how much is out there?
What Is the Probability That Intelligent Life Exists Beyond Earth?
People much smarter than I have tried to calculate the probability that intelligent life exists. Guys like Princeton researchers David Spiegel and Edwin Turner created one of a few different equations that may give us the probability of extraterrestrials hanging out somewhere.
Their equation is based mainly on abiogenesis. They consider the metrics required to calculate how probable abiogenesis is in worlds that are conducive to it. From there, their formula considers how many of these worlds may exist. They use a Bayesian statistical analysis to do so. If you don’t know what Bayesian statistics is, just watch an episode of the game show “Let’s Make a Deal” with Monty Hall.
Here is their equation:
Please don’t ask me what any of that means. They went to Princeton. I’m not even allowed into Princeton's gift shop (don’t ask).
Search for Extra-Terrestrial Intelligence (SETI) researcher Frank Drank came up with a simpler approach to estimating how many civilizations may exist. His equation only accounts for the Milky Way. It also doesn't calculate for how often abiogenesis occurs. Instead he just considers how often life actually appears, no matter how it got there. Here is his take:
N = R * fp * ne * fl * fi * fc * L
Where:
N = the number of civilizations in the Milky Way galaxy whose electromagnetic emissions are detectable
R = the rate of formation of stars suitable for the development of intelligent life
Fp = the fraction of those stars with planetary systems
Ne = the number of planets, per solar system, with an environment suitable for life
Fl = the fraction of suitable planets on which life actually appears
Fi = the fraction of life bearing planets on which intelligent life emerges
Fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L = the length of time such civilizations release detectable signals into space
Unfortunately for David, Edwin, and Frank, we know almost none of the variables to input into their equations. Frank Drake estimates that there are 10,000 civilizations in the Milky Way galaxy alone. But as we know, this may be far from accurate.
The odds seem high, however, that intelligent life exists out there.
So…
Why Haven’t We Met Any Aliens?
Michael Hart, astrophysicist and white supremacist (not relevant information but someone should mention it), explored the Fermi Paradox in detail in a paper he published in 1975. He detailed four arguments for why we haven’t met any aliens yet. He argued that intelligent life exists, but there are reasons we haven’t encountered them yet.
1. There is some physical difficulty about long range space travel that is making it impossible for aliens to reach Earth.
You might think that space travel is easy despite the distance. What’s the big deal, right? Once you’re going, there’s no wind resistance. You don’t even need to have powerful rockets because you can just slingshot around a planet to propel yourself to incredible speeds.
The thing is that space isn’t as safe as you think it is. One spec of dust (literally) can blow up your entire craft. That’s if you’re traveling at only 20% the speed of light. To get to Alpha Centauri, the nearest star system to Earth, would take about 26.25 years at that rate. To traverse the stretches of the galaxy worth exploring, an extraterrestrial would need to travel much faster. That would make that speck of dust significantly more dangerous.
Unlike Fermi’s claims, intelligent life might need more than just modest rocket technology to get to us.
2. Aliens just decided that Earth wasn’t a cool destination.
Fair point. We are pretty cool. But if you can travel across the entire Universe, you might have found other places more worthwhile to be. Why come to Earth if there are just a whole bunch of semi-evolved monkey’s who can’t even get off their own planet?
3. Advanced civilizations arose too recently to have the technology to reach us.
We homo sapiens have only been in our current state for 75,000 years. That is a tiny blip on the cosmic clock. Imagine an intelligent species needs only 5,000 more years of technological advancement to reach us. People will never get the chance to see them. Even though on a cosmic level, they are close to having the ability.
It took us one-third of the Universe’s existence to evolve. With it possibly taking so long for intelligent life to exist, we might just have to wait a bit longer until an intelligent species reaches us. The percent chance that our evolutionary timescales lined up in such a way to meet at this moment could be low.
4. Aliens are here, we just haven’t seen them yet.
They could just have a little outpost on Jupiter or something. Maybe they are hiding in that big red circle on its surface that we keep thinking is a giant storm but really it’s just an eyeball staring at us from afar. Making sure we are safe. Or waiting for our demise.
I've thought about this a bit, as you can probably tell. I like Hart's arguments, even though I don't like the fact that he is a white supremacist. But that is neither here nor there. I personally believe that the odds are in the favor of extraterrestrials existing somewhere. When I consider some of the incentives of space travel, I came up with a couple of my own conclusions as to why we haven't seen any intelligent life yet.
5. *If aliens can travel across the Universe, they just might be able to travel out of it.
There is this theory bouncing around astrophysics that argues our Universe may not be the only one to exist. That means multiple worlds. Maybe parallel worlds.
The possibilities of places to go are so numerous here in this Universe. There’s a lot to see in our home world. The percent chance an Intelligent life form can sift through all the possible planets, find us, and get to us is low.
If you add in another dimension like multiple universes, it’s easy to argue that aliens might just be preoccupied exploring other worlds entirely.
6. *Maybe they are just reading and daydreaming.
If you have enough information to travel across the Universe and to other universes, you probably have learned a lot about why you are here. Maybe their days of exploration are over. Maybe, just like everything else in life, exploring the Universe loses its appeal.
They’d rather just be at home with a good book, learning how to be happy.
Works Cited
Courtland, R. (2008, September 8). 'Water Bears' are first animal to survive space vacuum. New Scientist. https://www.newscientist.com/article/dn14690-water-bears-are-first-animal-to-survive-space-vacuum/.
Drake, N. (2021, May 4). Why we EXPLORE Mars-and what decades of missions have revealed. Science. https://www.nationalgeographic.com/science/article/mars-exploration-article.
Fox, D. (2007, March 28). Primordial Soup's On: Scientists Repeat Evolution's most famous experiment. Scientific American. https://www.scientificamerican.com/article/primordial-soup-urey-miller-evolution-experiment-repeated/.
Hille, K. (2016, October 13). Hubble finds 10 times more galaxies than thought. NASA. https://www.nasa.gov/feature/goddard/2016/hubble-reveals-observable-universe-contains-10-times-more-galaxies-than-previously-thought.
Howell, E. (2018, April 27). Fermi paradox: Where are the aliens? Space.com. https://www.space.com/25325-fermi-paradox.html.
Howell, E. (2018, April 6). Drake equation: Estimating the odds of finding e.t. Space.com. https://www.space.com/25219-drake-equation.html.
John Timmer - Aug 23, 2016 7:12 pm U. T. C. (2016, August 23). Just how dangerous is it to travel at 20% the speed of light? Ars Technica.
https://arstechnica.com/science/2016/08/could-breakthrough-starshots-ships-survive-the-trip/.
NASA. (2016, August 11). NASA climate modeling suggests Venus may have been HABITABLE – climate Change: Vital signs of the planet. NASA. https://climate.nasa.gov/news/2475/nasa-climate-modeling-suggests-venus-may-have-been-habitable/.
NASA. (2020, July 24). Goals. NASA. https://mars.nasa.gov/science/goals/#goal-1.
O'Neill, I. (2015, October 27). Earth bloomed early: A fermi paradox solution? Space.com. https://www.space.com/30889-earth-bloomed-early-fermi-paradox-solution.html.
Origins of Life. Origins of life on earth. (n.d.). https://www.lpi.usra.edu/science/kring/epo_web/impact_cratering/origin_of_life/index.html.
Shapiro, R. (2007, February 12). A simpler origin for life. Scientific American. https://www.scientificamerican.com/article/a-simpler-origin-for-life/.
Spiegel, D. S., & Turner, E. L. (2012, January 10). Bayesian analysis of the astrobiological implications of life’s early emergence on Earth. Proceedings of the National Academy of Sciences of the United States of America. Bayesian analysis of the astrobiological implications of life’s early emergence on Earth.