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Kindle Notes & Highlights
by
Stephen Webb
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March 15 - April 8, 2019
Lemmings breed quickly—about 3 litters per year, with each litter containing up to 8 offspring. In just a few years the total mass of lemmings will be equal to the mass of the entire terrestrial biosphere. The Earth must be swarming with lemmings. And yet most of us see no evidence that lemmings exist.
Lemming
in other words, the “Universal Year” compresses the entire history of the universe into 365 days. On this timescale, a second of real time corresponds to 437 years; in the Universal Year, western science begins about 1 second before midnight on 31 December.
Wow
An entertaining science fiction story from the 1950s suggested that the reason so many people dislike spiders is that the class Arachnida consists of alien creatures. They were carried here on some spacecraft, and then escaped; humans, instinctively recognizing the spiders’ alien heritage, recoil from them.
Wow
A few investigations have been performed to test the idea, and analysis of certain types of viral DNA has found nothing resembling an artificial pattern. Now that biologists have sequenced the entire genome of several creatures, including man, more detailed searches could be performed for coded messages.
O
With each breakthrough in the study of genetics it becomes increasingly apparent that all life on this planet is deeply related. Perhaps individual species are not alien, but we can’t discount the possibility that every species came from the same extraterrestrial source. Perhaps life itself is the message. Perhaps we are all aliens.
Wow
Crick and Orgel felt that the chance of viable microorganisms landing on Earth after an interstellar journey measured in light years was small. But deliberate seeding is different. Directed panspermia is the suggestion that an ancient ETC deliberately aimed spores toward planets with conditions favorable to the survival of life. Maybe primitive life didn’t arrive here haphazardly inside a meteorite; maybe it was sent here via a probe.
O.panspermia
The reason there seems to be no interaction between them and us is that they don’t want to be found—and they have the technological ability to ensure we don’t find them. The zoo scenario involved the idea that advanced ETCs are simply observing us.
Zoo
Yet the zoo scenario specifically predicts that we should not see flying saucers or any other manifestation of superior technology. If flying saucers are spacecraft then the zoo scenario is wrong.
O
(James Deardorff proposed a variant of Ball’s idea, known as the leaky embargo scenario, which is compatible with observations of flying saucers. The idea is that advanced and benevolent ETCs have put in place an embargo on official contact with mankind. But the embargo is not total: aliens contact those citizens whose stories are unlikely to be credible to scientists and the government. The aliens want to slowly prepare us for the shock that might come later when they reveal themselves.
Leaky embargo scenario
There is something unsatisfying about an approach in which, no matter how hard we look, no matter how thoroughly we search, the absence of ETCs is explained simply by saying they don’t want us to see them. (I can explain the lack of observational evidence for fairies at the bottom of my garden by saying they become invisible whenever people look their way. Irrespective of whether fairies exist, this is a poor sort of explanation from a scientific standpoint.)
However, a further weakness is that the zoo scenario fails to explain why aliens didn’t colonize Earth long before complex life-forms appeared:
Wow
A more serious criticism is that it takes only one ETC to break the embargo, just one immature civilization that decides to poke its fingers through the bars of the cage, for us to see them here on Earth. Furthermore, it fails to explain why we observe no evidence of them out there in the Galaxy. The proposition here is that intelligent life is ubiquitous, so where are their astroengineering projects? Where are their communications? It’s one thing for them to keep Earth free from development, but quite another for them to stop all activity on our account.
Wow
He argues that, in a steady-state era, knowledge will be the most valuable resource. Advanced ETCs would have a reason to leave a life-bearing planet well alone, if only because the planet will provide a non-renewable source of information.
non-renewable source of information
I find it implausible that truly alien intelligences, if they exist, can communicate so efficiently that they reach “an enhanced level of understanding [and] mutual agreement”. The problems in establishing a transgalactic communication system go way beyond mere translation difficulties.
O
Is it possible, Baxter asks, that the world we live in is a simulation—a virtual-reality “planetarium” engineered to present us with the illusion that the universe is devoid of intelligent life?
Wow
The planetarium hypothesis suggests that our commonly accepted understanding of the external universe might be wrong. Exactly how wrong depends on the type of planetarium the ETC has provided for us (“low-tech” as in Truman or “high-tech” as in Matrix) and also its scope—the position of the boundary between human consciousness and external “reality”.
Jacob Bekenstein showed how quantum physics places a limit to the amount of information a physical system can code. The uncertainty relations show that the amount of information inside a system of radius (in meters) and mass (in kilograms) can never be greater than the mass multiplied by the radius multiplied by a constant (which has a value of about bits per meter per kilogram).
Wow
how could we ever know whether our universe was artificially produced in a laboratory inside some other universe?
Perhaps, no matter how technologically advanced a species becomes, it can’t overcome the barrier of interstellar distance.
Distance
We have no problem understanding the idea of a positive mass; nor is there any difficulty with the idea of a zero mass; we can even ascribe meaning to negative mass (and note that, if negative mass existed, we might be able to use it in a propulsion device). But imaginary mass? Whatever it might mean, physicists have searched for signs of it. So far, the tachyon remains hypothetical.
We are taught in school that massive objects attract one another by exerting a mysterious influence through empty space. Einstein’s general theory of relativity presents a very different picture of gravity. In this view space—or rather, spacetime—plays an active part in the gravitational interaction. In the words of John Wheeler: “mass tells spacetime how to curve, and curved spacetime tells mass how to move”.
O
The Casimir effect —a small attractive force that acts between two uncharged parallel conducting plates brought into close proximity—is the clearest example of the existence of zero-point energy (ZPE). The effect can only be explained in terms of quantum fluctuations of the electromagnetic field.
Magnet
On this timescale, civilizations might have been popping into existence since the late spring months, and there seems to be no compelling reason why the first ETC couldn’t have arisen by about May Day. So although the first species with the inclination and ability to engage in interstellar travel might have arisen at any time in the 8 months between May and December, according to Hart the temporal explanation asks us to accept that this species started traveling no earlier than 11:21 PM on 31 December. It would be a remarkable coincidence if our civilization emerged so soon after the
...more
Wow
The small probes travel at and perform fly-by investigations. If a probe detects intelligent life it lets the home planet know; if it detects nothing it moves on to the next unexplored star. Once the probes have visited all 40,000 stars on the list they return to the host, which moves to a new destination star and the exploration process starts afresh. Using this method of exploration, Bjørk found that it would take about 300 million years to explore just 4 % of the Galaxy.
Wow
We can argue that interstellar travel is slow and expensive, that ETCs haven’t reached us because there hasn’t been enough time for them to reach us. Equally, we can argue that interstellar travel is fast and cheap for a civilization with a sufficiently advanced technology. Personally, I’d like to think that our descendants would think of ways to explore the Galaxy under reasonable timescales. And if we were able to do that, so could others in the past.
An ETC having no uncolonized stars within reach will, of necessity, develop a culture lacking the colonization drive. Therefore any given colony will have some probability of developing into a colonizing civilization, and a probability of developing into a non-colonizing civilization.
Wow
For the two-dimensional array shown in the illustration, each cell, except those on the edges, can have four neighbors: the cells directly above and below, and to the left and right. Percolation theory deals mainly with how these neighbors and clusters interact with each other, and how their density affects the particular phenomenon being studied.
Percolation
The percolation approach thus suggests that colonizing extraterrestrials have not reached Earth for one of three reasons. First, , and any colonization that has taken place stopped before it reached us. Second, , and Earth happens to be in one of the large uncolonized volumes of space that inevitably occur. Third, , and Earth is in one of the many small unoccupied voids.
O.percolation
If you haven’t played Game of Life, do try out one of the freely available simulation systems—it can be quite hypnotic to watch a pattern evolve: some patterns blink; others oscillate; yet others glide across the space, or eat the gliders.
Game of life.cellar automata
Models of galactic colonization based on diffusion (such as the Newman–Sagan proposal), percolation (the Landis proposal) or cellular automata (Bezsudnov and Snarski) make statements about the migratory behavior of species that are assumed to hold true over timescales measured in hundreds of thousands or even millions of years. Colin McInnes developed a model of migration that only needs to hold true over a period of a few millennia in order to account for the lack of extraterrestrial visitors here on Earth.
Main
the likely characteristics of a young civilization that has just found itself with the technological capacity to succeed at interstellar migration. He argues that if a species has the drive and motivation to develop the necessary technologies then the species is likely to be highly competitive, since it would have had to outcompete other species during its early evolutionary development.
Or explorative
If a species realizes that it can engage in interstellar travel on a large and economic scale, and in doing so exploit new material resources, then it isn’t going to hold back.
any subgroup of that species will find it can gain a competitive advantage by colonizing space and acquiring new resources: there will be a race to get out there and take advantage of the opportunities. Wealth, activity and population will continue to increase, and the species will experience a wave of economic expansion. For a while, the species will have never had it so good. They aren’t likely to stop.
Mentality.
McInnes shows that in order to maintain a constant average population density the migration speed must increase linearly with radial distance from the home star. But at some point that migration speed will be equal to the speed of light.
Light cage
So here is a scenario that explains why we haven’t been visited. Any civilization that develops the ability to embark on large-scale, economic colonization of its stellar neighborhood inevitably collapses within a few thousand years because its rate of migration can’t possibly match its growth.
Wow
Civilizations pop in and out of existence, and they aren’t here because they never get beyond the light cage limit.
One way of avoiding the trap would be to keep net population growth very low, although there might then perhaps be dangers associated with the stagnation of the civilization. Another would be to constrain growth once the limits of resource are reached, but to allow rapid growth at the frontier.
How to avoid
Establishing a human colony on an inhospitable exoplanet would presumably take at least a thousand years; a more realistic estimate is that it would take a hundred thousand years. This is an eye blink in cosmic terms, and hardly worthy of mention in computer models where one “tick” represents a dozen millennia.
Even a long-lived and fixed culture might at some time reorder its priorities. Faced with these sorts of timescales, they might simply give up on the notion of large-scale colonization.
Dyson once suggested that a KII civilization might choose to tear apart some of the planets in its system and use the material to create a sphere that encloses the star. By doing this, all the star’s energy output could be utilized; compare that with the situation on Earth, where we intercept only a billionth of the energy emitted by the Sun.
Dyson sphere
China was the leading maritime power of the day. Indeed, China was probably the most technologically advanced nation on Earth. But after the deaths of Zheng He and the Xuande emperor, and for reasons that are still debated, China ceased its expansionist policies, forbade foreign trade, and embarked on an inward-looking path.
Inward
Ćirković argues that postbiological civilizations will be motivated by a different definition of success: it won’t be measured in terms of the extent to which they control space but rather the extent to which they control the substrate of their environment. In particular, success will probably be measured in terms of the amount and quality of digital computation they can access.
Wow
Ćirković argues that technological civilizations will deliberately choose a different developmental path—perhaps one based on a “city-state” rather than imperial model.
Wow
In a lecture first given in 1948, he discussed the relevance of self-reproducing automata to the question of life. He argued that a living cell, when it reproduces, must follow the same basic operations as a self-reproducing automaton. Within living cells, there must be a constructor and there must be a program. He was right.
Reproducing automation
In an interview with a Time magazine reporter, von Neumann said: “If you say why not bomb them tomorrow, I say, why not today? If you say five o’clock, I say at one o‘clock.” We must be grateful that, in the 1950s and 1960s, wiser counsel than von Neumann’s prevailed.)
O
The Kolmogorov complexity of the second string is large because there’s no obvious way of compressing the information it contains; any program describing the string would likely be as long as the string itself. Gurzadyan argued that the Kolmogorov complexity of the human genome—indeed, of the totality of terrestrial life—is relatively low.
He describes the possibility of a Galaxy in which ETCs establish a network of self-replicating Bracewell–von Neumann probes and life is propagated not by sending the genomes themselves but by sending the programs that can recover the genomic information.
Wow
if berserkers exist, then how come we are here? Berserkers should already have sterilized our planet. Instead, as we shall see in later sections, the geological record indicates life has been present on Earth for billions of years.
Wow
So why have berserkers silenced all other civilizations but left us alone? We could argue that berserkers destroy only technological life-forms and need a “trigger”—presumably the detection of radio waves—before they begin work.
Wow
It might shout for help—perhaps it’s facing a long-term existential threat that it hopes other civilizations have surmounted and could advise upon—or at least announce its existence if it knows its end is nigh. It might want to brag about its cultural achievements and high points. It might want to convert others to its religion, or sell information, or simply shout out to try and end a sense of loneliness. There are numerous possibilities.
