The Fermi Paradox

It's the day before Thanksgiving. Breakfast Bytes will be dark Thursday and Friday. But today, the day before a break, I write about something that has little (okay, no) connection to semiconductors and EDA. I thought today I'd write about the Fermi Paradox.

The paradox is named after the physicist Enrico Fermi. He is most well-known for creating the world's first nuclear reactor. This was part of the Manhattan Project and was created under one of the stands at a stadium at the University of Chicago. It had the catchy name "Chicago Pile-1" since it was a pile of 45,000 graphite blocks (400 tons), along with 6 tons of uranium and 50 tons of uranium oxide. It was the world's first self-sustaining nuclear reactor. Apart from the obvious developments in nuclear science, this is also why nuclear reactors are often referred to as "piles". This original pile had no cooling since it ran at such low power, about half-a-watt. It became operational on December 2nd, 1942.

The Origins of the Fermi Paradox

After the war, Fermi worked at Los Alamos National Laboratory. The story goes that one day in 1950 Fermi and some colleagues were walking to lunch. The conversation turned to UFOs since there had been various sensational stories in the press. The conversation then moved on until when, in the middle of lunch, Fermi exclaimed: "Where are they all?"

What he meant was that given the vastness of the universe and the massive timescales in cosmology, the universe, and in particular the Milky Way Galaxy and the solar system, should have been full of extraterrestrials from other civilizations, or at least signs of them.

Another standalone statement of the Fermi paradox is, "If the universe is teeming with aliens, where is everybody?"

The Drake Equation

Some of this was put on a more numerical basis in 1960 by Frank Drake at the first meeting of SETI (the Search for Extra-Terrestrial Intelligence).

The Drake Equation is:

N = R_* . f_p . n_c . f_l . f_i . f_c . L

where

• R_* is the average rate of star formation in our galaxy
• f_p is the fraction of stars that have planets
• n_c is the average number of planets that might support life for each star with planets
• f_l is the fraction of those planets that actually do develop life
• f_i is the fraction of those planets with life that develop intelligent life
• f_c  is the fraction of those that release detectable signs of their existence into space
• L is the length of time they release such signals

That gives N, the number of civilizations with which communication might be possible. I don't find the Drake Equation especially useful since either you set one of the numbers to 0 (and get 0 for the number of civilizations) or else the number of stars is so large that almost any fractions give a large number of civilizations. There are estimated to be 400 billion stars in the Milky Way galaxy. But Drake has said much the same thing, that the equation was never meant to be a numerical calculation, more something to stimulate discussion.

Since Drake proposed his equation, one number has become more concrete: f_p. We now know that planets are fairly common since we have discovered lots of them. Outside the solar system, these are known as exoplanets. As of 1st November, the Interactive Extrasolar Planet Catalog says there are 3,874 known exoplanets.

The Fermi paradox is that the Drake Equation gives large numbers for N under reasonable assumptions, but the observed number is 0.

Are We Unique?

One possibility is that we are unique. Either life is so rare that we are the only life in the universe, or at least the galaxy. Alternatively, life might exist elsewhere but not develop technology. Planets could regularly be full of algae and we would never know.

Since we exist and have technology, and are beaming electromagentic radiation into space, we know that none of f_l, f_i, or f_c are zero (fraction of planets with life, fraction of life with technology, fraction of technology that communicates). However, it is possible that the numbers of those fractions are so small that life is really unlikely. In fact, it is almost an impossibility that we are here. Even with millions of people playing and a billion dollar jackpot, nobody won the Powerball lottery in mid-October. Even when we know the probabilities the number can be zero.

A nuance is that we might be the first civilization to develop technology, and that others will be along later. Or perhaps they are already there but the signals have not reached us yet. This may not be as unlikely as it sounds since the universe may have only cooled enough for life to be possible "recently".

We have very little idea how life got started. Evolution provides a mechanism for guiding how things work out once the process gets going. We know from the 1953 Miller-Urey Primordial Soup experiment that given reasonable assumptions about early planetary atmosphere, we can get amino acids, the building blocks of proteins. But it is a long way from there to self-reproducing life. In John Casti's wonderful book Paradigms Lost (now sadly out of print) the chapter on the origins of life concludes that we are alone. Other opinions are available.

Is Technology Self-Limiting?

A more worrying possibility is that L, the length of time that civilizations emit signals, is limited. The most likely reason for this is that any civilization with enough technology to have radio transmission also has enough technology to destroy itself.

The general focus of this is nuclear weapons, going back to Fermi's day job as a nuclear physicist on the Manhattan project. But nuclear weapons don't have any sort of "Moore's Law" going for them. There is greater understanding, but the critical mass of Uranium-235 is still 52 kilograms, and you don't find it lying around in nature. To destroy civilization requires a lot more than a single nuclear bomb. A couple of years ago the San Francisco Chronicle did a piece on what would happen to the city if a nuclear bomb were detonated. They picked the 16th and Mission BART station for ground zero, about 2 blocks from where I lived at the time, so I was in the total vaporization zone. But if San Francisco was taken out, it would be bad for those of us that live there, but the rest of the US would carry on. 

I'm more worried about biological weapons.

It used to take the national laboratory of a major nation-state to consider developing a biological weapon. But genetic engineering and techniques like CRISPR-Cas9 are changing that. You probably still need a university or biotech startup laboratory, but that sort of chemistry gets automated. It took billions of dollars and a decade to sequence the human genome, but now it can be done for thousands of dollars, and a limited sequence by sending $100 to 23andMe.

In the future, it may be possible for an individual, or at least a small group, to develop something really bad like smallpox, or a version of the flu that has just the right characteristics (it doesn't kill you too fast, so you infect lots of people, but eventually it does). It is possible that one explanation for the Fermi Paradox is that every civilization has to get through the bottleneck where a single individual can destroy the whole civilization.

As it happens, security expert Bruce Schneier's latest book echoes this theme. The title is Click Here to Kill Everybody: Security and Survival in a Hyper-connected World.

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There are several books on the Fermi Paradox. The one I have actually read is: If the Universe Is Teeming with Aliens ... WHERE IS EVERYBODY?: Seventy-Five Solutions to the Fermi Paradox and the Problem of Extraterrestrial Life by Stephen Webb. It is apparently on to a second edition.

Happy Thanksgiving

Happy Thanksgiving to all of you and your families.

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