By any account Enrico Fermi was a brilliant man, and by most accounts a genius. He was born in 1901 and lived in an epoch of human discovery and enlightenment unparalleled in history, and probably one that will not be matched for generations to come. He witnessed the expansion of the universe, not in any actual sense of it, but through a developing human perspective of it. In the late nineteen twenties, Edwin Hubble discovered that the limits of the universe extended far beyond the Milky Way Galaxy, and that many of the stars in the night sky were not stars at all, but other galaxies consisting of hundreds of billions of stars. Each time Hubble looked through his Telescope the universe grew bigger.
Fermi will long be remembered for his work in nuclear physics for which he received the Nobel prize in 1938. During World War II he was a key player in the Manhattan project. After the war, as Fermi entered his twilight years, he began to wonder about the universe and the possibility of extraterrestrial life. Fermi reasoned, if Earth was a typical planet having only evolved in the last 4.5 billion years, that in a universe 13.8 billion years old, there should be a lot of other Earth like planets and on them a lot of intelligent beings. But where are they? Why is intelligent life so inconspicuous in the universe. It’s a problem known as the Fermi paradox.
Fermi believed that there must be extraterrestrial life out there somewhere, but he was a scientist and as a scientist he knew that he and anyone else could believe anything they wanted. In science you had to know, and what was needed was immutable evidence, the proof positive. The eminent Dr. Carl Sagan put it this way, extraordinary claims require extraordinary evidence, with respect to notions of extraterrestrial visitation, and no proof meeting this level of scrutiny has yet been offered by those proclaiming such visitations. But Fermi reasoned, that if Earth-like planets and intelligent creatures exist elsewhere in the universe the evidence should be there, it should be all over the place, far to difficult for any government conspiracy to cover up. The other possibility, that we humans here on a rare planet are a singularity that has waited 13.8 billion years to occur in the universe, was a notion to immense, to incomprehensible to even contemplate.
Scientist and physicists especially, like to quantify their thoughts with numerical representations in the form of mathematical equations. In a formula, also known as an equation or expression, you state what you know as constants, and what you don’t know, you quantify as variables. But is you have enough bits and pieces of the problem you can resolve the unknowns by rearranging the formula and using one known as a proof to resolve some unknown factor. In 1950, Fermi in one instance during lunch with a few colleagues, developed just such an equation to resolve the probability of extraterrestrial intelligence. Fermi’s problem may well have been the impetus that would motivate Frank Drake to frame a much more elaborate equation in 1960, the Drake Equation.
Fermi’s equation basically took into account the numerical enormity of the number of stars in an average galaxy, a percentage of those stars which would have Earth-like planets, and the number of galaxies known to exist in the universe. As it turns out, the number of galaxies is the biggest variable, as new galaxies further out in space are being identified every day. The Hubble Space Telescope has breached entirely new dimensions of cosmic understanding, to the degree that what we have learned about deep space and galactic formations in the past 19 years dwarfs what was known previously. For instance, now we know that the majority of stars we can see out there are binary stars. Stars that orbit around each other, and due to the gravitational turbulence around them are not likely to have planets. Take this into account, and the possibility of other earth-like planets is reduced by 50% or more.
Another interesting point, is that our own solar system is located in a pretty quiescent neighborhood. Surprisingly, there have been no supernovae explosions in close proximity to Earth, probably since the formation of the solar system which is the remnant of such cataclysmic event. It has been established, that the gamma radiation from a supernova within 300 light years of Earth would destroy all life on the planet. In other parts of the galaxy, there is a whole lot of activity, like stars smashing into other stars, marauding black holes, and who knows what else that would make the chemical evolution that leads to intelligent life improbable. Apparently, there were a lot more variables to consider than Fermi’s or even Drake’s equation ever took into account.
Enrico Fermi died of stomach cancer in 1954, but the quest to resolve the paradox he had so eloquently framed continued. In the early 1960’s NASA began a project called Search for Extra Terrestrial Intelligence (SETI). With the aid of new radio telescope technology, it was thought that the evidence of other intelligent life in the Milky Way would soon be at hand. Scientists theorized, that if their were other intelligent beings out there who had been around as long or longer than the human species, they too would have discovered electromagnetic radiation and be transmitting signals like the radio and television signals humans have been transmitting for only the past hundred years. If so, we should be able to detect these intelligent signals.
We have been listening and searching the cosmos for half a century now, albeit sporadically, but all that has been obvious to this point is a deafening silence. The tell tail signs of alien beings scientist were sure they would find fifty years ago remain elusive. There are those who may think they have solved the quandary, but as Fermi put it, if so, where is the evidence that should be there? Where are these extra terrestrials? And so it is, that the paradox, Fermi’s paradox, awaits resolution by some other brilliant representative of the human species.
