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by
Stephen Webb
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March 15 - April 8, 2019
The argument in favor of this inevitability relies on another supposition: that our universe is a system presently engaged in a life cycle. Smart takes as his inspiration here the relatively new ideas of evolutionary developmental biology (“evo-devo”, as it’s often known).
Evo devo
In a paper co-written with the futurologist Robert Bradbury, Ćirković argued that intelligent life will arise at various points in the Galaxy and, if such life survives all the natural and self-initiated disasters that fate throws at it, will inevitably pursue a trajectory that leads to postbiological evolution.
Post biology
While many of the challenges facing present-day computers will eventually be overcome by employing different designs or fancier technology, the issue of heat dissipation arises directly from the laws of thermodynamics. The problem of heat dissipation will restrict the computational processes of even the most advanced technological civilizations—assuming they are bound by the laws of physics—and, since information processing is assumed to be the guiding motivation of such civilizations, Ćirković and Bradbury argue that this restriction will dominate their policies.
How thermal hinders development
in order to improve the efficiency of their computing, ETCs will migrate outwards from their original location to the cold outer reaches of the Galaxy. They’ll move from a “galactic habitable zone” to a “galactic technological zone”—and the galactic rim will be home to a collection of individual, highly advanced “city states”. The reason we don’t see advanced civilizations in our neighborhood is because they, or their computers, find it intolerably hot here.
Wow.Cold places
Ultimately, though, these solutions depend upon making one or more of the terms in the Drake equation tiny. If a single term is close to zero, or else if several of the terms are small, the effect is the same: when all the terms are multiplied together, the result is . There are no others.
Wow. True
We are bound by the Weak Anthropic Principle (WAP), which states that what we can observe must be restricted by the conditions necessary for our presence as observers. Since it’s impossible to avoid the WAP in a discussion of the Fermi paradox, it makes sense to begin this part of the book with a Solution based upon anthropic reasoning.
Once oxygen and ozone levels were high enough, Earth’s surface was shielded against ultraviolet (UV) radiation in the wavelength region of 200–300 nm. This shield was important because it protected two key ingredients of cellular life: nucleic acids and proteins.
O
Livio argues that, as on Earth, the timescale for developing an ozone shield against UV radiation is roughly equivalent to the timescale for the development of life.
O
If life on Earth is typical of life elsewhere, then most life-forms will be carbonbased. Livio therefore suggests that the emergence of ETCs will coincide with the peak in the cosmic production of carbon.
O
Oort Cloud comets that delivered water to our planet—water that we still drink every day. At first glance this suggestion makes sense. Some planetologists argue that the very early Earth would have been too hot to hold on to large oceans of water, so the water we have now must have been delivered from space;
the biochemistry of terrestrial organisms, and the biochemistry of any extraterrestrial organisms we can plausibly imagine, depends crucially on six elements: hydrogen (H), sulfur (S), phosphorus (P), oxygen (O), nitrogen (N) and carbon (C). In astronomical terminology, therefore, life depends upon hydrogen and the five metals SPONC.
O. SPONC
However, none of those metals essential to life were there at the beginning of the universe. Where did they come from? The heavier elements were all cooked in nuclear reactions inside stars, and became part of the interstellar medium only when stars reached the end of their energy-producing life. As time goes by, the concentration of metals in the universe slowly increases.
Wow
the heavier elements only recently became sufficiently concentrated in the interstellar medium to allow life to form. Planets around older stars, it is suggested, lack the metals SPONC. Only around quite young stars—stars such as the Sun—can life arise. So humankind is inevitably among the first technological civilizations to arise. Perhaps it’s the first.
Wow
how often is a supernova event likely to occur close enough to Earth to cause a mass-extinction event? Well, estimates vary but a mid-range estimate is that a supernova event will occur within 30 light years of Earth on average every 200 million years or so. If that estimate is accurate we have another question to ask: why are we here?
Wow
a Mars-sized object, which has since been given the name Theia, struck the infant Earth in an off-center impact. The unimaginably violent collision ejected a mixture of terrestrial and impactor material into orbit around Earth, and this material quickly coalesced to form the Moon.
Read it somewhere
Earth’s obliquity, without a Moon stabilize it, would also wander chaotically—to values as large as . Even an object with half the mass of the Moon, which would be a relatively large satellite, would have insufficient heft to stabilize Earth’s tilt. Our home planet requires a large satellite to prevent its obliquity from wandering and its climate shifting from one extreme to another.
Wow
The solution of the problem of life is seen in the vanishing of the problem. Ludwig Wittgenstein, Tractatus Logico-Philosophicus
O
First, a living object must be made of cells. Every living creature on Earth consists either of a single cell or a collection of cells. If we knew how cells originated, then we might well be on the road to understanding how life itself originated.
Life?
Second, a living object must have a metabolism. Metabolism is what we call the variety of processes enabling a cell, or a collection of cells, to take in energy and materials, convert them for its own ends, and excrete waste products. In other words, all living organisms require food of some description and all living organisms create waste.
Life?
Third, a living object can reproduce—or else it derives from objects that could reproduce. Cells can reproduce either individually or in sexual pairs, and the mechanism of reproduction is DNA.
Life?
Fourth, life evolves. Darwinian evolution—natural selection acting on heritable variation—is a key aspect of life.
Life?
Nevertheless, in recent years tremendous progress has been made in two directions: on the one hand, tracing life’s ancestry back as far as possible, and on the other hand attempting to understand the chemical pathways that might have led to the earliest forms of life.
Two study direction
The “top-down” method of looking for the origin of life is the search for LUCA —the Last Universal Common Ancestor, the most recent organism from which all present life must have inherited its common biochemical structures.
LUCA
Unfortunately, biologists can push this approach only so far. One commonly drawn picture is that LUCA was already a sophisticated organism, which had evolved considerably from the time when life first arose, before it branched into the domains of archaea and bacteria.
Wow
We usually think of genetic information as passing only vertically—from parent to child. Early in the history of life, however, horizontal transfer of genes between different types of organism seems to have occurred frequently.
Wow
Rather than become bogged down in the details of LUCA, we can consider the “bottom-up” approach to the question of the origin of life. We can ask: how did the universal chemicals of life—nucleic acids and proteins—come into existence?
Main
In 1953, Stanley Miller performed a classic experiment in which he passed an electric discharge through a vessel containing a mixture of water, methane and ammonia. The experiment was intended to investigate the effects of electric currents passing through the atmosphere of the early Earth. At the end of his experiment, Miller found many organic compounds in the vessel. Other scientists have disagreed with Miller’s choice of model atmosphere, but the results were unarguably dramatic.
Water methane amonia
Serum albumin contains a chain of 584 amino acids, which are curled up into a sphere. In our bodies, the synthesis of the molecule is under the direction of nucleic acids. But imagine a time before DNA existed, so that a molecule of serum albumin had to be synthesized by adding one amino acid at random to the end of a growing chain. The chances are negligible—just 1 in —that random processes would produce the protein.
Wow
As the biologist Lynn Margulis famously put it: “The gap between non-life and a bacterium is much greater than the gap between a bacterium and man.” And yet this gap was bridged relatively quickly. Some scientists find it difficult to accept that life could have begun so early on Earth without help, and have resorted to the panspermia hypothesis
Wow
Bayesian analysis.
Gene sequencing leads some biologists to believe animals originated about one billion years ago, which, if true, means the fossil record relates to only half of the history of animal life on Earth.
Wow
Any animals existing before this period must have obtained oxygen for their tissues by diffusion, which is a slow process. Those animals would have had no heart—at least, no pump—nor would they have possessed a circulatory system. They would have been tiny, gossamer-like creatures, so it’s little wonder they left no trace in the fossil record. But then, for some reason that’s not entirely clear, the atmospheric oxygen level rose yet again in the Cambrian period. Several key evolutionary developments took place—gills, hearts, haemoglobin in blood—allowing marine animals to make much more
...more
O
The energy available to each copy of the gene remains about the same. Nothing is gained. Bacteria work just fine at a small size, but there’s an energy barrier that prevents them from getting bigger. If we ever discover extraterrestrial life, and find that it’s powered by a straightforward membrane potential, then the chances seem good that the life will consist of small, simple forms: those cells won’t be able to evolve the complexity that permit animals and, eventually, intelligence.
O
But any intelligent species will need some sort of precision-manipulative ability (whether using claws, tentacles or something beyond our imagination) in order to make tools and thus begin the journey to high technology.
Wow
Fabricating sharp stone edges in this way was an impressive feat—as mentioned earlier, even with intensive training our closest living relatives can’t match this simple toolmaking exploit of our long-dead ancestors. Not only did the fabrication of stone edges require insight (to realize that one object can be used to manufacture a second, more useful object) it required a large degree of dexterity and bodily control.
O
Individual Neanderthals must have lived short, hard lives, but as a species they survived for much longer than humankind has been around; they inhabited a large area of Earth; they coped with severe swings in climate; in short, they successfully filled a biological niche.
Wow
it’s possible to regard the Neanderthals as an intelligent toolmaking species that survived for more than 100,000 years without making significant technological advance.
Wow
if intelligence is defined as the ability to perform these basic non-verbal tasks, then one can argue that to a first approximation all birds and mammals, including humans, are about equally intelligent! This conclusion remains controversial, but if it turns out to be true we shouldn’t be surprised. After all, every species, including mankind, has to negotiate the same perilous world; we all have to eat and drink and find mates. The basic cognitive skills enabling animals to perform these tasks might well be common to all species.
Exactly
Noam Chomsky, who argues that language is innate. A child doesn’t need to learn language; rather, language grows in the child’s mind. In other words, a child is genetically programmed with a blueprint—a set of process rules and simple procedures that make the acquisition of language inevitable. All of us possess a “language organ”—not something a surgeon can cut out with a knife, but a set of connections in the brain dedicated to language in the same way that parts of the brain are dedicated to vision.
Wow
Critics have argued that if our language organ is the result of evolution then we should see traces of it in the apes. After all, we are descendants of apes, aren’t we? Well, no, we aren’t. Humans and apes are linked by a common ancestor that perhaps lived as long ago as 7 million years.
they underwent a restructuring of the diaphragm, larynx, lips, nasal passages, oral cavity and tongue, all of which were vital for articulate speech to develop, but none of which occurred in order for speech to develop. The changes to these organs were initially completely unrelated to the capacity for speech; they were small changes that brought immediate selective benefits.
Wow
At least one of the changes—the positioning of the larynx deep in the throat—seems bizarre. Having a larynx low in the throat provides the tongue with enough room to move and produce a large number of vowel sounds, but any food and drink we swallow has to pass over the trachea: choking to death becomes a distinct possibility. The benefits are great, but so are the costs. If the tape of life were replayed, perhaps humans wouldn’t develop language.
Wow
What’s the difference between being dead, and just not knowing you’re alive? Peter Watts, Blindsight
Wow
Damage to the occipital lobe can stop signals from reaching the mammalian visual system, but it wouldn’t stop those signals from reaching the reptilian visual system in the midbrain. If consciousness can access the advanced visual system but not the primitive system, and if the primitive system is associated with basic behaviors such as recognizing motion and positioning one’s body, then this would explain how blindsight occurs.
Sights
That recognition of movement causes the lizard’s tongue to shoot out and catch the fly: everything happens automatically. Consciousness is unnecessary for the lizard to survive. In fact, consciousness would be a hindrance for the lizard.
Wow
Waltham’s models suggest that if the Moon-forming collision had produced a satellite with a radius just 10 kilometers bigger than our Moon, and if the young Earth had turned so that its day was just 10 minutes longer than our Earth, then we would be entering the zone of instability right about now. Or imagine an Earth–Moon system that’s identical to ours in every way except that tidal drag is increased by a few percent; again, we would be just about to enter the zone of instability. Our days would be numbered.
Bilateral effect
When thinking about Graham’s number we start with this number, which is represented by . In other words, . The number is absurdly vast: Just four uparrow operators between the 3’s generates a number that’s too big to write comfortably.
Concept of big
We’re searching for ourselves… That’s the sense in which I mean the argument for the existence of extraterrestrial intelligence has an air of arrogance about it. When we look up into the night sky, why should we expect to find beings possessing precisely those qualities that define humanity?
My god
The millions of species with which we share our planet are all equally as “evolved” as us: they all earn a living in a harsh world that cares not whether they live or die. They manage to survive in a spectacular number of different ways. There’s no evolutionary drive towards the sort of intelligence that defines our species. If we don’t find intelligence here, why on Earth should we find it out there?
Wow
The famous French biologist Jacques Monod once wrote that “Man at last knows he is alone in the unfeeling immensity of the Universe, out of which he has emerged only by chance”. It’s a melancholy thought. I can think of only one thing sadder: if the only species possessing consciousness, the only species that can light up the universe with acts of love and humor and compassion, were to extinguish itself through acts of stupidity or ignorance.
Wow
