Are We Alone?
B.W. Wojciechowski, July 2021
At dinner conversations I have found myself involved in discussions of the probabilities of fulfilling all the requirements for the evolution of the human species and the evolution of intelligent life in general. Since such discussions tend to be disorganized and muddied by the wine being consumed, I thought it wise to put down on paper what I consider to be the principal requirements that have combined to yield a statistically unlikely milieu that has led to our existence. The argument is based on considerations which we all intuitively sense in making daily decisions. If my friend flips a coin ten times in a row, and comes up all heads I would certainly seek a cause for this unexpected event. The product of the required probabilities of the events which are responsible for our existence is many, many, times smaller. I believe the product of the probabilities outlined below justifies discussion of the hypothesis adopted by some that our existence is not a random event. It is intellectually timid to ignore the highly improbable combination of the issues without looking for a cause.
We have good reason to believe that the universe is built under the constraints of a set of universal physical constants. Below is a selection of the more familiar ones:
Planck constant h
Boltzmann constant kB
Charge on an electron e
Speed of light c
Fine structure constant α
Electron rest mass me
Proton rest mass mp
Gravitational constant G
In another but less familiar take on the matter, one can rearrange these and other fundamental constants to formulate a total of 26 dimensionless fundamental constants, such as the fine structure constant cited above. Dimensionless constants are the priceless gems of theories. They are all-powerful in their field since they apply regardless of size, mass, speed, time or any other quantity considered by the theory.
These 26 fundamental dimensionless parameters govern every aspect of our physical universe. They were fixed in the early phases of the Big Bang and, as far as we know, have not changed since then; nor do they vary throughout our universe.
The constants that were created in the Big Bang result in the energies created in today’s atomic fission and fusion reactions which, together with the potential of gravity, constitute the fundamental energy resources of our universe. They also govern the chemistry of our universe and of the world we inhabit. Every chemical reaction, every particle, every animal, every molecule formed owes its formation, its properties and its capabilities to these fundamental parameters.
The fundamental parameters lead to a zoo of consequences. The zoo contains many unique but essential “creatures,” such as water which we will discuss later. Our bodies and the world that surrounds us are all built on the basis of these parameters. Everything but one process, the process of thinking, is strictly initiated by these fundamental parameters.
Notice how precisely their values are known. Five figures are common and, in many cases, more are defined, as for example in the speed of light. The precision is not trivial, these specific values are important; they define the structure of the universe we inhabit. Deviation from any of these values would change the physics and chemistry of our universe. A Big Bang which gave rise to different fundamental parameters would result in a universe that would not create conditions necessary for humans to evolve.
It is amazing that our universe should have all 26 constants at the very specific values that make our universe possible. We have to accept that we must be very, very, lucky that our universe experienced the particular Big Bang that formed it. Or was it designed that way?
Let us consider some other essential developments that led to our existence. Once we had a long-lived universe with adequate gravity to form stars, galaxies and heavy elements, we were on the road to the formation of organic compounds. These compounds are also made possible by the values of the fundamental physical constants, by the longevity of the universe, and by the existence of places in the universe where concentrations, pressures, and temperatures were suitable for their formation from the original atoms formed in the Big Bang; i.e., starting from hydrogen and then in multiple steps proceeding to build heavier atoms as products.
Many of the atoms of organic compounds that form us could not have formed in the gases originally created by the Big Bang. Organic molecules contain atoms created by sequential “fusing,” of the original hydrogen and its primary products in star interiors, followed by the occasional releases of the heavier elements in Nova explosions. The Big Bang merely set the stage; much time had to pass and other events had to fall in place for atoms essential to our existence to be formed.
Our universe needed to be stable and yet active for a long time for these processes to finally produce enough of the heavier elements that formed from generations of star formations and Nova explosions, and that now constitute our Earth. The heavier elements that constitute the chemistry of our bodies, e.g. iron and oxygen, are the result of not one but multiple sequential star formations and explosions, followed by the formation of star systems from the condensation of dispersed clouds of products of the explosions containing enough of the heavier elements to form rocky planets. Some of these planets, Earth for one, had liquid water and atmospheres of gases such as carbon dioxide. We are composed of the ashes of generations of stars that have lived and died. This took time, an appropriate gravity, temperature and a reasonably stable universe.
As heavier-atom-containing planets were formed, their composition, orbital parameters and size differed widely from star to star and planet to planet. What permitted organic life to evolve on Earth was its stable and appropriate planetary orbit around a stable long-lived, mid-sized, and now middle-age star. This has resulted in conditions such that the average surface temperature on our planet remains within the limits of organic compound reactivity and stability. This permits complex organic reactions which finally led to the evolution of the structures of organic life. Not all planets are so lucky. There will not be a large number of planets such as ours, orbiting appropriate suns in “goldilocks” orbits. There are just too many alternative possibilities. Our Earth is a fortunate example of a planet that has all the prerequisites for intelligent life to evolve.
Add to this the fact that our Moon is much larger, relative to the planet it orbits, than any other satellite in our Solar System. This has had the effect that our Earth wobbles much less on its axis of rotation as it circles round the Sun than it would without the gyroscopically-stabilizing presence of our Moon. As a result, Earth’s seasonal weather patterns have remained more stable than they might have been. This fortunate property of our planet is conducive to the long-term regional stability which fostered evolution on Earth.
This climatic stability had to be maintained for billions of years. Earth’s organic life took more than three billion years to get to where we are. There were protracted periods of global glaciation and climate instability through which only the most primitive life forms survived. They survived because despite all, liquid water was available. Organic life-forms require water, the magic solvent that nourishes the formation of increasingly complex molecules. It is in an aqueous medium that life began. Not all planets we know have this important constituent in abundance in its three phases.
Water is a unique but common liquid which can act as a solvent for both organic and inorganic molecules and acts as an active participant in many of their reactions. Moreover, water is the only liquid that expands as it solidifies (freezes); otherwise, seas would consist of permanent ice at the bottom with a thin layer of seasonal, frigid, liquid water on top; not a satisfactory milieu for intelligent life to evolve. Water is a truly magic substance, unique among liquids, yet subject to all the requirements of the fundamental constants I have listed above. At this time, we do not know of a way to produce a chemistry which will result in living organisms without water.
To add to the requirements for intelligent life to emerge, we had to have both plentiful water and dry land. Marine organisms, no matter how intelligent, cannot harness fire, the energy required to begin to master nature and develop technology. Their milieu does not seem to encourage the formation of brains which will consider their own composition, functioning, or purpose. They are aware of their surroundings, they may have good recall of the past and form subtle sentimental attachments, but we do not believe they think of the esoteric concepts we have used to develop technology.
To achieve the conditions necessary for organic life to emerge from the water where it began and develop further, a land surface must persist for a long time. In the presence of plentiful water, rain and ice, a solid land surface on a planet the size of Earth would eventually erode, allowing the sea to cover the entire globe, with little or no dry land remaining. That would have prevented the development of land-dependent humans and their intelligence. Land animals with sophisticated nervous systems which in due course led to intelligence have existed for a minute fraction of the time of Earth’s existence, no more than 500 million years, arising some 4 billion years after Earth’s formation and more than 13 billion years after the Big Bang. In a static world with significant oceans, it is likely that by the time any potentially-intelligent beings could emerge, there would be no dry surface to thrive on.
Fortunately, the Earth’s land surface is not stable. Earth has a molten core, providing the material and energy for the solid surface to be renewed. This is partly due to volcanic activity, but a major factor is continental drift leading to mountain-building and land-replenishment. Both these activities are powered by the internal energy of the Earth’s core. A smaller planet would have cooled more quickly, as Mars did, or a larger one may have become static and uninhabitable due to being totally covered by seas.
A much larger planet, with all the other requirements for life to evolve, might have made organic life forms capable of developing intelligence impossible, due to the gravitational forces on the structures of organic organisms which would limit their size, dexterity and mobility. Organic structures have a limit within which their bones and joints can carry the weight of the organism on land. Those who wish may postulate boneless creatures resembling Earth’s octopi as an intelligent, sophisticated, land-dwelling species on much larger rocky planets. But could such beings develop an advanced civilization? Perhaps.
On the other extreme we might imagine huge creatures with massive bones; dinosaurs. But Earth’s dinosaurs did not become an intelligent species, despite millions of years of dominance and opportunity, perhaps because the development of their brains did not get priority in competition with the requirements of controlling their physical bulk. Earth seems to be ideally configured for intelligent, dexterous, land-dwelling organic life. Few of the planets formed in orbit around other stars will meet the many requirements we have just discussed, and others too numerous to enumerate here.
As it happens, primitive Earth-based organisms possessed a profoundly important capability: they consumed the carbon dioxide of our original atmosphere using the Sun’s energy and “excreted” oxygen. That was critical to what followed. Oxygen is a very active element, and normally would be completely consumed by oxidizing atmospheric reducing gases and inorganic solids on the planet’s surface. But with the persistent and long-lasting production of oxygen exhalations and carbon dioxide consumption due to the early organisms, it accumulated in Earth’s atmosphere. We are critically dependent on this organism-polluted atmosphere.
In due course oxygen removed most of the reducing gases such as ammonia and carbon monoxide, oxidized various elements on Earth’s surface, and allowed an oxygen-rich atmosphere to form. This amazing process required a long and stable time for the primitive organisms to produce enough oxygen to oxidize most of the original atmosphere as well as a great deal of the planet’s surface solids. It is oxygen that allows us to be as active and intelligent as we are. Carbon dioxide eating organisms have low-energy metabolisms and are generally completely immobile, like trees. There are dozens more such requirements for our existence, each with a probability of less than one. The product of these many probabilities is very small.
So: has intelligent life evolved elsewhere in the universe? May be. Is it likely? Not very often, according to the above requirements, as quantified by a modified form of the Drake Equation expanded to include even more requirements than those we have considered above. In the Drake Equation, since each additional probability is less than one, each new requirement reduces the probability of whatever it is one may wish to calculate.
To add a couple more requirements, think of our magnetic field, and the continental drift that maintains a land surface we live on. These may not be present in other midsize, rocky, well-watered planets, orbiting in the goldilocks zone. And there are many more requirements, each with a fractional probability which diminishes the overall chance of intelligent life arising. A fully expanded Drake Equation has many such probabilities each requiring a property or circumstance which is essential for the development of intelligent life and each introduces a new fraction to the product of the other probabilities.
The possibilities of what may be formed spontaneously are huge, fixed, and immutable. They are circumscribed by the 26 parameters. But the probabilities that something will be formed or happen are of two kinds: those due to spontaneous events resulting from the random interactions of the 26 parameters and those we, and other intelligences, can alter using our wits and technology. This is critical to understanding if we are alone.
We, other intelligent beings, or an all-powerful God, can alter probabilities, though perhaps not the possibilities which are baked into the universe. Let me show you how. To build a 747 jet, or even a cell phone, we require many types of materials, many processes involved in their extraction and modification, and a lot of appropriate energy, carefully applied, in all the intervening activities. What are the chances of these needs coming together spontaneously to build a 747? Zero. Yet we have them. So 747s are possible within the 26 parameters which govern the universe. But they only exist because we, using our wits and energy, have manipulated probabilities to make them possible. This is but one example of how our wits and technology alter probabilities of the appearance of otherwise improbable things. Humans too are possible but highly improbable in the simpler world of spontaneous events.
Now, other intelligent species could also have arisen spontaneously. Though, as we discussed, it is highly unlikely they did so in large numbers. But let us say that some did. Since our galaxy and our solar system are recent arrivals on the scene, there may have been intelligences that arose millions and billions of years before us. Since all things in our active universe are in danger of disruption or even total elimination, the early intelligences may have by now met their end. However, some may have survived in one form or another, there is therefore a real, non-zero probability that some ancient civilizations exist. What if one or more such intelligence is still around and knows of our existence?
Consider the pace of technological progress we have made in the past 200 years. I don’t know if this pace can be maintained for long but certainly a civilization a million or more years old must have developed technology we cannot begin to imagine. We can speculate what it may be but the only thing we know is that their technology is likely to be constrained by the 26 parameters we discussed. Even within these constraints the possibilities of developing unimaginable devices is essentially limitless. We can, therefore, reasonably expect that an ancient civilization will have capabilities we cannot foresee.
What we have no hope of predicting is what their goals are and what principles govern their activities. In fact, it is entirely possible that a civilization that old consists of inorganic beings who owe their existence to an extinct, preceding, biological lifeform. After all inorganic beings seem to be more robust and potentially even more clever than we biologicals. We ourselves are on the road to giving life to inorganic entities with the development of AI robots. How would alien, hugely advanced inorganics, see our organic life-form? Are we just bugs to them or fellow adventurers-to-be?
Intelligent life originating in more than one civilization may have colonized our Galaxy and they may be in contact with one another. Are they cooperating in watching our evolution and waiting for us to grow up and join them? Are they a peaceful lot or are we to believe ancient Hindu and other religious writings of aliens warring over conflicted interests and/or our Earth’s future?