English as a Sacred Language: the path to a global ecclesia

Latin was once considered a sacred language all over Western Europe. Today, we can see English as a global sacred language, but how long will it maintain this role?

Imagine living in Western Europe after the fall of the Roman Empire. With the collapse of the Roman government, Europe had fragmented in a myriad of cities and statelets, each one with its territory and its language. Starting from your home town, it was enough to travel for a few hundred miles to find yourself in a land where nobody could understand you, nor you could understand them. You didn't even need to cross the border of the main linguistic blocks of the European territory (Romance, Anglo-Frisian, Germanic, Slavic, and more). Just the internal variation of each block was enough to make communication impossible.  It was the Babel tower again.

But the old Roman Empire had left a heritage that kept Europe as a single cultural entity: Latin. Once the language of a small city-state in central Italy, it had spread all over the Empire as the language spoken by the legionnaires, the bureaucrats, the governors, and the tax collectors. All that was gone, but Latin had remained, too useful to disappear. It was the language of commerce, of diplomacy, of pilgrims. of travelers, of intellectuals, and, more than all, it had morphed into a sacred language used by the Catholic Church. It was the language of the holy Christian books. Even though God had never spoken in Latin to anyone (we are not completely sure of the language of the original Christian books: probably Greek, but perhaps Aramaic or Hebrew), Latin was sacred in the deepest meaning of the term: something set apart from everyday use. It was the language that kept together the ecclesia, the assembly of the citizens of Europe. Latin was not just a commercial language, it was a noble language, above and separated from all other languages.

Other languages had played and were playing the role of sacred languages in this sense. Sumerian had been perhaps the first, remaining in use long after the Sumerians had ceased to exist as a separate population in Mesopotamia. Then, contemporary to the Latin of Middle Ages, the Koine version of Greek remained the common language of the Eastern Mediterranean and the sacred language of the holy scriptures of the Orthodox Church. Earlier on, God had spoken to Moses in Hebrew and, around the same period, the Archangel Gabriel spoke to Muhammad in Arabic, giving a sacred characteristic to that language, too.

As universal languages, all these were rather provincial ones, used only in limited regions of the world. As the Middle Ages waned, Europe started to grow, moving along the trajectory that would take Europeans to dominate the whole world. The European armies could have taken Latin with them, restarting on a large scale the process that the Roman Legions had started long before. But that didn't happen. Latin didn't expand beyond Europe and it waned even as an intellectual language. Newton still wrote his Principia in Latin in 1687 but, a century later, Latin had become a relic of old times. It was still used by the Catholic Church for its ejaculatory prayers, but little more than that.

There were good reasons for the demise of Latin as a would-be global language. For one thing, it was too provincial: as soon as Europeans started expanding in faraway continents, Latin was useless for dealing with the locals. More than that, the development of the printing press gave a big boost to national languages. When books were handwritten, they were hugely expensive and it made sense to write them in a universal language (Latin) that ensured their widest diffusion. But the printing process made it possible to write books also for people who didn't understand Latin. The printing press was a powerful factor that caused the fragmentation of Europe in nation-states. Without a common language, people couldn't understand each other anymore. The result was the great massacre that we call today "the 30 years war."

Still, the loss of a universal language was a big handicap for commerce and for culture. For a few centuries, the struggle for world domination was at the same time a military struggle and a struggle for the prevalence of a specific European language. Spanish did well in South America, French made an attempt to dominate worldwide out of sheer boasting, German became diffuse as a scientific language, and Italian found a niche in the bel canto of Opera. Some people dabbled at reinventing new languages from scratch, such as Esperanto. Even more creatively, the Catholic Church attempted to develop a new kind of international language, not based on words, but on icons and images. It was a bold attempt, but it failed. In this age of European dominance, non-European languages, Swahili, Chinese, Arabic and others, had no chances to be anything more than regional languages.

Eventually, military might gave to English the right to become the first truly global language in history. Carried first by the British legions, then by the American ones, English is spoken nowadays by at least 1.5 billion people and probably understood by many more than that. It is the one language that gives you a chance to be understood and to understand the locals everywhere in the world.

In religious terms, English has never been as directly linked to God's words as Latin and older languages were, although many people claim to have received revelations in English directly from God. But English became the language of the Ecclesia, the assembly of the citizens of the world and, for this reason, it can justly claim to be sacred in the sense to be special, set apart. Besides, English does have a sacred corpus of scriptures: more than a century of scientific research, practically all of it written in English. It is from this corpus that a sacred creature called Gaia, may one day emerge. Not a Goddess, but the very spirit of the Earth, a new reference point for the human ecclesia.

And from now on? Despite the ongoing fall of the American Empire, English could follow the path that Latin had followed centuries before. It could expand and maintain its leading role as the world's global language. Or it may not. Just as Latin was destroyed by a technical improvement, the printing press, the same could happen for English. It could be mercilessly replaced by a new language that we could call "Googlish," the result of the Google translating engine.

I am not so happy at seeing English disappear, because it is a language I know reasonably well, even though I am not a native speaker. But I can see the writing on the screen. For one thing, my Italian students can't speak English anymore and they seem to be surprised, at times shocked, when they discover that science is normally written in English. Even my Italian colleagues sometimes seem to write in English with the same ease and attitude of someone undergoing a root canal treatment (with some commendable exceptions). 

What surprised me even more, recently, is how efficient automatic translators have become. A friend of mine, a professional translator, used Google to translate one of my posts in English and publish it in his blog in Italian. The result was far from perfect, but it was readable and it required just a few retouches to be made smooth to read. 

Even more than that, I was amazed at seeing the discussion that's taking place on my Facebook pages. I tend to write mostly in English on Facebook, but I write in Italian about subjects that I think are of more local interest. The interesting thing is that people often comment in both languages, in Italian on the English pages, and in English on the Italian pages. They understand each other. Evidently, it is a small miracle worked by the automatic translator embedded in Facebook. The beauty of this way of communicating is that you don't have to be ashamed of your poor English (or your poor Italian). You speak in the language you know best and the mistakes are a fault of the translating engine. And you can communicate with almost everyone on this planet. It had never been possible up to now.

So, are we going to build a true planetary ecclesia, realizing the dream of those who invented Esperanto? Maybe. So we can conclude with a quote from the Ecclesiastes (it means "the person who convenes the assembly"). It goes as, "there is a time to keep silence, and a time to speak." It sounds very wise when applied to our social media.

Is Gaia a Superorganism? No, she is a holobiont!

A few days ago, I was discussing with a friend and he used the term "superorganism" for Gaia as the Earth Goddess. When I said that Gaia is not a superorganism but a holobiont, he asked me, "but what is a holobiont, exactly?" I thought about that for a while, and then I said, "a holobiont is a democracy, a superorganism is a dictatorship."

If you have a friend who is a biologist, try to tell her that Gaia is a superorganism. Likely, she won't be happy and she might ask you, rather venomously, "And so, tell me, good sir, how could natural selection have generated this -- ahem-- 'Gaia' of yours? You tell me that there is only one Gaia on this planet and so, in order to evolve, did perhaps different planetary ecosystems in the galaxy competed with each other?" I am not inventing this, it is the scathing criticism of the Gaia theory that Richard Dawkins produced in his book, "The Extended Phenotype" (1982).

Given a certain interpretation of Darwin's idea, Dawkins' position is logical and even unavoidable. There is just one problem: the common interpretation of Darwin's theory is wrong.

Don't misunderstand me: Darwin was one of the greatest scientific geniuses in history. But we need to take into account that he was working on limited data and with limited tools. He himself could never decide exactly between two concepts that he used interchangeably: "natural selection" and "survival of the fittest." They are not the same thing, not exactly at least. If you emphasize the idea of the "survival of the fittest," then you see evolution as a continuous competition among the best in the search for the even better. It is a cutthroat competition, nature in red tooth and claw.

But it doesn't have to work that way. An alternative view of evolution is more compatible with the idea of "natural selection" and it takes its inspiration mainly from the work of Lynn Margulis (1938 - 2011). In brief, the unit of evolution is not the organism (at least, not only the organism) but the holobiont. And evolution is not competitive but mainly collaborative. 

It is a long story, and I invite you to read the fundamental book "Symbiotic Planet" (Margulis, 1998). See also an article of mine on "Cassandra's Legacy" and my Facebook group on holobionts. To summarize, holobionts are collaborative societies of organisms that live together, helping each other. A good example is a human being, a community formed of the main organism (the proper "human"), and a large number and variety of micro-organisms (the microbiota) that live inside and on the surface of the main organism. Every living being on this planet is a holobiont, and there are holobionts formed of smaller holobionts: think of a forest. Trees are holobionts, a forest is a holobiont formed of trees. Holobionts are a self-similar entity operating at various scales.

Then, evolution is a mechanism for keeping a population stable. It operates mainly at the bottom, not at the top. Those organisms which are defective because their genome is damaged, those that Gorshov and Makarieva call "decay individuals" (Biotic Regulation and the Environment, 2000), are removed and the genetic information contained in the population is maintained intact in order to regulate the system. It is not the "survival of the fittest" but the "non-survival of the unfit."  It is a mechanism that sheds entropy away from the system.

Holobionts do compete, but the concept seems to be (this is an interpretation of mine) that while organisms search for perfection, holobionts strive for the good enough. Mostly, holobionts just survive. And those that survive tend to shed away those parts of themselves which are not good for survival. Holobionts continuously exchange genetic information with other holobionts (it is called "holosex"). In this way, they teach survival techniques to each other. You could say that holobionts are a democracy, while organisms are a dictatorship. (you might also say that holobionts are communists, but that means pushing the similitude a little too much.)

So, back to Gaia, now it should be clear that Gaia is a holobiont, just like us (see also this article by Castell et al.) You could call Her a super-holobiont that includes all the smaller holobionts of the biosphere. Then, this idea overcomes Dawkins' objection: Gaia exists not because She competes with other superorganisms. She exists because the sub-holobionts that form Her collaborate with each other. Think of a forest: did it evolve by competing with other forests? No. It came to exist because trees survive better together than alone. The same is true for Gaia. She operates like all other holobionts. She survives because the living beings of this planet survive better (actually, only) if they are together. Gaia is what She is.

The beauty of this concept is that it gives a form and a substance to Gaia that other views don't provide. So far, Gaia has been an abstract term, mostly described in terms of scientific models and equations. But if She is a holobiont, well, the Goddess is one of us! She is a living being just like us. And when you pat, touch, or caress another human being, you are patting, touching, and caressing the Goddess herself. You can do that with your dog, too! We, living creatures of the biosphere, all partake in the same holobionticity!

And so things stand: onward, fellow holobionts!



See my also facebook group on holobionts  and Erik Assadourian's site on Gaianism
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Note: these ideas are not new, after all: 

“I will sing of well-founded Earth, mother of all, eldest of all beings. She feeds all creatures that are in the world, all that go upon the goodly land, and all that are in the paths of the seas, and all that fly: all these are fed of her store. Through you, O queen, men are blessed in their children and blessed in their harvests, and to you it belongs to give means of life to mortal men and to take it away.” Homeric Hymns,

The Cinderella Strategy: How to Restart the Italian Economy by Building a Bridge Across the Messina Strait

The former Italian prime minister, Mr. Silvio Berlusconi, evoking the Messina Strait by a magic spell in an image taken probably around  2002. As a modern version of Moses, Mr. Berlusconi didn't manage to do much more than creating a scale model. But the idea of building this monster (it would be the longest suspension bridge ever built), has been recurrent in Italy for decades. It is a dream that refuses to come true, no matter how much politicians get their inspiration from Cinderella.

The story of the Covid-19 epidemic never ceases to surprise me for one reason or another. Wrong models, superstar scientists, terrorized citizens, non-existing vaccines sold at high prices, the police fining people for taking a walk, snake oil in great abundance, and more. But this really hit me badly: would you believe what the Italian government is considering, now? Yes, in order to restart the economy after it was hit so badly by the lockdown, they are thinking of building a bridge over the Messina strait to connect Sicily to Italy. (really!). The longest suspension bridge ever built, assuming that it were possible to build it -- not obvious at all. It is a Cinderella-style dream that, likely, will never come true.

Maybe it is true what some people said, that the Covid-19 can sometimes affect people's brains, but the real explanation is another one: the unbreakable grip of obsolete ideas on the way people think. In times of crisis, leaders simply tend to go back to the solutions to old problems, without realizing that times have changed. So, we need to return to growth, we need to stimulate the economy, we need to build large infrastructures, we need (this too is being said!) to get rid of these stupid regulations about pollution that prevent the economy from restarting to grow.

That explains the return to the recurring idea to build this bridge that has been around for decades. Probably, the leaders are sincere in their feeling that if it were possible to start building this monster, then it would be a good thing for the Italian economy (and, of course, some of their friends would make a lot of money as a side effect). The concept that the economy needs energy and resources to keep going (to say nothing about expanding) is wholly alien to the people in charge.

So, will the bridge be built? Of course not, (see below for an explanation). But we'll hear about it for some more time and some money may be wasted on preliminary studies. What's truly fascinating is how economic thought has not budged of an inch after that Robert Solow proposed his economic model that saw growth as generated by an entity called "total factor productivity." Whatever that was, it couldn't be defined or measured, but it was supposed to grow exponentially forever and push the economy to grow in the same way. Natural resources didn't appear among the parameters of the model.

And so we are condemned to follow our dreams in a Cinderella world, always thinking that, if you keep on believing, the dream that you wish will come true.

Why the Messina Strait bridge will never be built. A note on energy based economics

Image from Tim Morgan, "Surplus Energy Economics"

The idea that the economy depends on the supply of energy should be obvious to anyone who ever owned a car. Take away the gas, and the car doesn't move, no matter how much you tinker with the carburetor. And it is not just cars that work in this way. Everything that moves, moves because it uses energy to move. If you want to say that in a fancy manner, you can say that living creatures, engines, hurricanes, rivers, and more move because they dissipate energy potentials. No energy potentials no life and no movement. 

It is hard to think that the human economy doesn't depend on the same factors. Indeed, one of the founders of economics, William Stanley Jevons, had already understood the question in his work on coal in the mid 19th century. But over more than a century of work, economics has drifted away from concepts related to physical factors. For some reason, economics, as it is today, remains linked to the idea that things such as the energy supply are not fundamental in affecting the performance of the system -- if they are considered at all.

The idea that things are different -- a lot different -- remains marginal and heretic, but it persists and over time it may gain some space -- although it takes an awful amount of time and effort. To learn the basics of the idea you can check the blog by Tim Morgan, "Surplus Energy Economics". Right now, he has a post that reviews the whole concept. It is an interesting read, highly recommended. 

One remark about Morgan's description: When he discusses the entity called "ECoE" (energy cost of energy invested) he doesn't seem to notice that it can be set as equal to 1/EROEI, the energy return on energy invested. Of course, you have to measure the cost in some units, and energy is the best one in this case. 

The behavior of ECoE is described by Morgan in qualitative terms as a parabolic curve -- going through a minimum (maximum prosperity) and then shooting up. If we equate ECoE to 1/EROI, it is not exactly so. This rate tends to taper off with time, as we found in a study we are preparing right now with my colleague Ilaria Perissi. Here is how our model describes the behavior of ECoE for a non-renewable energy source, such as oil.

You see that it tapers off, rather than growing quadratically as in Morgan's qualitative model. But that doesn't mean Morgan's model is wrong, it is approximately correct and, in any case, note how the cost of energy increases of a factor of a hundred over the depletion cycle (in the assumptions of this specific run). It means that some energy is still produced at this high cost only because the amount produced is reduced to a trifle. Note also that Morgan's curve takes into account technological progress and jumping from one source to another; our model doesn't. For an in-depth analysis, wait for the paper we have in preparation 

In any case, no matter what measurement you want to use, EROI or ECoE, the result is the same: there is no hope to keep going forever with a non-renewable energy source. Maybe you don't need models to understand this point, but take this one as a confirmation of what common sense tells us.

h/t Rafal

Are Face Masks Useful Against the Epidemic? Political and Scientific Questions

Are face masks useful against the Covid-19 epidemic? As obvious, it depends on various factors: the WHO says there is no scientific evidence of a benefit from the generalised use of masks by "healthy people in the community." But it is also stated that masks are beneficial when used in special conditions. Here, I tell you what I found about the scientific literature, but first I'll discuss how people tend to approach the problem according to their political views.

This is a modified version of a post that appeared in Italian on "Effetto Cassandra"


The Covid-19 epidemic is winding down in Italy, just like everywhere in Europe. The data indicate that the average mortality in most countries has been below average during the past three weeks, at least, and the curve shows no signs of picking up again. In Italy, there are still a few scattered cases, mostly in Northern Italy, but the numbers are minuscule. On all counts, the epidemic is over.

As a consequence, the use of face masks is not mandatory anymore in most regions of Italy, except inside shops, buses, and other crowded places. I expected that people walking in the streets would gladly shed their masks and enjoy the fresh air of these last weeks of spring, but many didn't. An informal measurement that I made during the past few days shows that if you take a walk in Florence you'll see a good 30% of the people still wearing masks tightly fitted on their faces. Another 30%-40% wear the mask loose on their face, leaving free the nose and often also the mouth. The rest don't wear masks at all.

Curiously, wearing or not wearing the mask seems to be linked to political opinions. In the US, it has been noted that the use of masks is more widespread in "blue states" than in "red states," those supporting Trump. Even more surprisingly, the mortality in red states is lower than in blue states (of course, that's not necessarily linked to the use of masks).

In Italy, things seem to be similar. I have no statistical data, but from what I read and what I see, I can tell you that left-oriented people are in favor of masks, whereas right-oriented ones are not. As it happens more or less everywhere, every issue discussed on social media soon becomes political with two opposite and incompatible opinions. It also happened with masks and extreme opinions are the rule. I received a comment to a post of mine that went as "If we don't wear masks we'll all die." Then, a well-known right-wing member of the Italian parliament, Mr. Vittorio Sgarbi, aired an emotional speech in which he maintained that "Masks are not only useless, they are harmful!"

For a discussion of why most people just can't approach this issue from a rational/data-oriented viewpoint, you can see this post by Chuck Pezhensky. Here, I am trying to do the currently undoable: examine the subject from a rational viewpoint. This approach has already caused someone to shout at me on Facebook "you are an abhorrent negationist" when I stated that things were not so bad as described in the media. But so is life and let me try to tell you the results of a search I made about masks on scientific literature. Just a quick disclaimer: I don't pretend to be a medical doctor, but I do pretend to be able to examine and analyze data. It is my job (*).


To begin with, what is the main route for the transmission of these viruses? On this point, you can read a recent review (in Italian) that summarizes what we know. To go more in-depth in the matter, you can read a hugely interesting article by Shaman and others. It is not very recent (2010) but it provides a complete description of how respiratory diseases diffuse and about their seasonal nature.

From these and other articles and documents, we can conclude that the main vector of the epidemic is the cloud of "droplets" emitted when infected people breath, cough, or sneeze. Instead, the so-called "fomites", particles that stand on solid surfaces and infect by contact, play a marginal role. But it seems logical that diseases affecting the respiratory system are transmitted mainly through the respiratory tract.

At this point, we need to understand how and under what conditions these "droplets" spread and reach other people. Here, the story becomes fascinating. It is clear that the droplets produced by sneezing, those visible to the naked eye, are basically harmless since they quickly fall to the ground. If that was the only problem, we wouldn't need masks at all. But smaller particles, those below a micron (millionth of a meter), are much more effective as vectors. The term "aerosol" is used for a suspension of these particles. You can find a very interesting clip on this matter at this link.

The measurements show how these particles remain airborne for a long time indoors and spread even at a distance of several meters. In practice, an aerosol may saturate a closed space and that makes social distancing useless. Not only that, but their persistence depends on the absolute humidity of the environment. In dry environments (a typical indoor condition), droplets partially evaporate, become even smaller, and the virus remains airborne for longer times. The opposite happens in humid environments.

These characteristics explain why influenza is a typical seasonal disease, as Shaman and others explain well. In summer, the absolute humidity is higher, and therefore the particles forming aerosols may grow in size and fall to the ground. It helps that people keep the windows open longer, which makes the aerosols for ventilation disappear quickly. The ultraviolet rays of the sun also help a lot, but of course only outdoors.

At this point, the question is whether the masks block the emission of aerosols. The answer is " in part, yes." One problem is that there are so many types of masks and that people often don't wear them correctly. But we can say that, in general, any mask -- even a simple damp cloth -- will block at least a fraction of the small droplets that generate aerosols -- you can see that effect here.

So, is wearing mask sufficient to have an effect on the diffusion of the epidemic? It seems that the answer is positive. A recent study by Leffer et al. shows that there exists a correlation between the use of face masks and the speed of diffusion of the Covid-19  epidemic. That's to be taken with some caution because it is difficult to disentangle the many parameters affecting the diffusion pattern, but it makes sense. Also the recent study by Chu et al. confirms that face masks reduce the transmission of the virus.

On the basis of these data, I would infer that the place where it is easiest to get infected is at home, where you often find yourself in poorly ventilated and dry rooms, especially in winter. From that, you could deduct that locking people in their apartments may not have been a good idea and, indeed, Leffer et al. find no evidence that the lockdown had any effect in slowing down the spread of the epidemic. But for the moment we do not have enough data on this point.

Now we can summarize.

1. The virus is transmitted mainly as an aerosol in indoor and poorly ventilated areas, in winter. In these conditions, social distancing is of little use.
2. In these environments, masks can help a lot, but it would be better to ventilate rooms as much as possible and try to keep them moist. It is even better to stay outdoors as much as possible, exposing yourself to the sun.
3. In conditions where there is no crowding and there is no evidence of the presence of infected people, masks are not needed. This is what the WHO says in their recommendations.
4. Most people will ignore the above points ad behave according to their political orientation. 

And this is what I found. If you know more than me or have different data, please feel free to comment. In science, nothing is ever carved in stone, you can and you should change your mind when new data become available.

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(*) About the right to speak on scientific matters, let me cite again Chuck Pezhensky: 

"One of the reasons I fervently believe our current society in the U.S. is collapsing is the loss of noblesse oblige — the idea that those of us that are better off in some definable way should help those who are less fortunate. I view my role as a full professor as one where I am supposed to think about complex and complicated things for the common good, just like a rich person is supposed to build housing developments for the poor."

Why do people touch each other all the time? Sex among holobionts

Nowadays, we are encouraged to exterminate our skin microbiome by means of various poisonous substances. But this is not a good idea. We are holobionts, and our microbiome is part of us. If we kill the microbiome, we kill ourselves. Touching each other is a way to keep our microbiome alive, it is a form of sex ("holosex") intended as a form of communication.  The lady in this picture seems to understand the point, at least judging from her unhappy expression. (see also the "proud holobionts" group on Facebook)

Humans tend to touch each other. They hug, pat, rub, kiss, cuddle, clutch, caress, clasp, embrace, each other a lot. Think of the kissing habits ("la bise") that's typical of the French society, it is done also in Italy and in other Latin countries. In most societies (*), at least some kind of skin contact is supposed to be a sign of reciprocal trust and confidence.

But, today, we are seeing a completely different pattern diffusing all over the world. With the coronavirus epidemic, people are not shaking hands anymore, to say nothing about kissing and hugging each other. Not only people don't want to touch other people, but they are also positively scared of getting close to each other. It is called "social distancing" and it involves a series of ritualized behaviors of dubious efficacy against the epidemic that include wearing face masks, sanitizing one's hands, spraying disinfectants all over people and things, raising plexiglass barriers, and more.

So, what's happening? Is social distancing just a temporary need or something that will last in the future? The answer depends on whether skin contact is useful for something: if it is not, we could as well abandon it, apart from strictly reproductive needs. But why do people touch each other? For one thing, we may be reasonably sure that if touching each other were harmful to us, natural selection would have eliminated this behavior from our genetic pool and from our cultural habits. On the contrary, touching each other has positive advantages. It is because we are all holobionts.

Let me explain: I am a holobiont, you are a holobiont, all the living creatures surrounding you are holobionts. The term is a little abstruse and still scarcely known, but it has been making spectacular inroads in biology from when it was proposed by Lynn Margulis in 1991. You probably heard of Margulis as the co-developer with James Lovelock of the concept of "Gaia" as the control system of Earth's ecosphere. And, yes, Gaia is a holobiont, too!


So, what is a holobiont? It is a community of living beings that share food, shelter, resources, and protect each other. A tree is a holobiont, a forest is a holobiont, a coral reef is a holobiont, your dog is a holobiont. And, as I said, as a human being you are a holobiont. You are an entity formed of a human organism and a large microbiome formed by a complete ecosystem of microorganisms living on your skin, colonizing your gut, helping various hormonal syntheses more or less everywhere in your body. Without a microbiome, you wouldn't survive for long, although you may eke a precarious existence with a reduced set of the full-fledged version.

And, as a holobiont, you are having sex all the time with other holobionts (and, yes, with your dog, too!). That needs to be explained as part of the great fascination with the concept of holobiont. We are starting to develop a definition of "sex" that goes beyond the conventional one. In our case, as humans, we think of sex as the exchange of genetic material between a male and a female of the same species (actually, we also practice non-reproduction oriented varieties of sex, but that's another form of communication). The result of reproductive sex is meiosis and a new individual with a mixed genome. It is called also "vertical sex," meaning that genetic material is transferred from parents to offspring.

In contrast, the horizontal gene transfer is the movement of genetic material from a donor organism to a recipient organism that is not its offspring. Bacteria, by far the most common lifeform on Earth, exchange genetic material simply passing it through their membranes, a mechanism called "conjugation." And viruses are great genetic exchange machines: they are packages of DNA and RNA that move from a host to another.

A holobiont is, as they say, another kettle of bacterial culture. It is formed of an ensemble of organisms, so it doesn't have a proper genome. But it has a hologenome, the ensemble of the genomes of the organisms that compose it. The hologenome has the same meaning of the genome, it is the "blueprint," so to say, of the holobiont. And, since holobionts are living creatures, they are born and die. So, the hologenome must be transmitted from one to the other. It is the transmission of constitutive information. It is a kind of sex that we may call "holosex."

By means of holosex, holobionts transmit hologenetic information from an individual to another. It is in this way that evolution occurs: "bad" holobionts, meaning those which are unstable, or unable to ensure the survival of the organism, are de-selected and disappear. It is a form of natural selection, not exactly in the neo-Darwinian sense, it has a certain degree of "Lamarckian" transmission of information. If a holobiont has developed a capability that other holobionts don't have -- say, resistance to a specific parasite -- it can transmit it directly to others by the exchange of micro-organisms. There is no need to wait for the population to be replaced by a new generation of individuals who have inherited a certain trait.

But then, how is exactly that holosex, sex among holobionts, works? Well, you don't need special organs and, of course, there is no male/female distinction. Hologenetic material is mainly in the form of microbial lifeforms of various kinds. To exchange these tiny critters, holobionts need to be in contact with each other or, at least, close to each other. Then, the passage of microbes mainly occurs by means of skin contact, although there are other possibilities.

That's why holobionts tend to touch each other: they hug each other, they pat each other, they rub each other, and they kiss each other: it is to exchange chunks of their hologenome, performing holosex, if you like to use this term. They tend, as we can imagine, to be cautious in doing that because they could exchange "bad" microbes and be infected with some illness. As we all know, sex is necessary, but nobody ever said that it is not dangerous. Holobionts need holosex in order to transmit and maintain their hologenetic structure and they need to accept that there is some risk involved. No sex, no life. Not for long, at least.

This means that, sooner or later we'll go back to touch each other and, perhaps, in France they will restart with la bise. Now, it looks as obsolete as dancing rituals to the moon Goddess in the night, but that may return, too. And so, onward, fellow holobionts!

(*) it may be possible that the Japanese exchange microbiota by means of their habit of communal hot baths, notoriously a place where bacteria thrive, So, they don't need to touch each other as much as Europeans do.

(**) To know more about holobionts and discuss the subject, see the "Proud Holobionts" group on Facebook

You are What you Read: How to Manage your Personal Echo Chamber

Mr. Trump has often being accused of "lying" in his many speeches and tweets. For sure, much of what he says can be said to be "contrary to fact." But is the president really lying or is he simply stating what he thinks truth is? One man's lies are another man's truth. And the problem is that people tend to see the world according to the different echo chamber in which they live. Everyone seeks for facts that support their opinions. We badly need to take control of the information flow that we receive and I think we can do that. Let me show you how I try to do it by disclosing my personal information bubble.

Not long ago, I stumbled in a comment on "Quora" for the question, "Why do some people deny climate change? Here is a shortened version:

CO2 levels of 400 ppm being dangerously high are not accepted by scientists I find credible. There is no significant sea rise. The temperature has not changed by even 1 degree C. over the past century. Climate Change has not increased hurricanes or their intensity. I may rethink this if there is an undoubtedly measurable change in the level of the seas, or a decade long temperature rise.

Now, if you are an average reader of "Cassandra's Legacy" you'll agree with me every statement in this paragraph is wrong in the sense of being "contrary to fact." But I am sure that the writer of this paragraph is a good person. He signed with his full name and I could see his profile. I think that if he were a neighbor of mine we could be good friends (as long as we would avoid discussing climate science!). He truly believes in what he says and he thinks his vision of the world is the right one.

What's wrong here? How can it be that "truth" is so different depending on the viewpoint? The problem is that we all live in an "information bubbles" or "echo chambers" where views are shared with other members of the same bubble/chamber. And if everyone thinks that something is true, then it is very difficult for a single person to deny that something -- even to imagine that it could be completely false.

So, we badly need to take control of the information we receive. We need to select trusted sources and balance the voices we hear in such a way to see things from different viewpoints. Otherwise, we are easy prey for the simplest propaganda tricks, continuously used against us. Silly tricks, but they work. And they work very well. Can we avoid this trap? I think so, but it takes some work.

First of all, I believe that blogs are by far the best source of information we have. Of course, you know that blogs are somewhat out of fashion in a word where your attention span can't hardly digest more than one or two paragraphs. Blogs are supposed to be passé, and their long texts are static and don't fit in the narrow screens of cell phones. Nobody has time for blogs anymore.

But blogs are special for several reasons, including the fact that in most cases they are still kept by individuals. It means that beyond the screen there is a human being whom you can come to know well enough to trust (or mistrust). Opening a blog page is like meeting a friend: you know his defects and his virtues, you know what to expect from him.

Then, within limits, blogs have the advantage of providing permanent information. The number of posts in a blog is limited and normally you can retrace old posts, something you can hardly do with Facebook. Digging into the old posts of a blog is like discussing with an old friend, when it may happen that he'll tell you a story of the old times, or of when he was a boy.

Of course, you know what the problem with blogs is: you have to actively look for them, unlike the standard social media. It means it takes a certain effort to keep track of the blogs you like. Again, it is like keeping alive a good friendship: it takes some effort.

But there is a way to turn blogs into something that automatically comes to you. It is called "Feed Reader." It is a very simple app, but I am always surprised to note how few people use it. With a feed reader, you can keep track of all the blogs you are interested in. You open your reader and there you are: in front of a list that you can customize at will and that, unlike on the typical social media (Facebook and the like) you completely control. You decide what you want to see and you won't miss a single post of the blogs you like, unless you want to.

I started using a feed reader years ago with "Google Reader," it was a very simple and nice app that worked wonderfully until Google decided to push it under the bullet train. I think it was not casual that they did that. But never mind: there are plenty more feed readers. You can find a list at this link. I use one called "The Old Reader" that looks very much like the old Google Reader.

So, what can you do with one of these readers? One bad idea would be to build yourself a nice and tight "information bubble" where you will never be bothered by people who don't think exactly the same as you do. It may be a risk but I think it can be avoided. In my case, I did what I could to try to use the reader app to gather information from a wide variety of sources. Did it work? I am not sure but I'll let you decide by showing you my personal information bubble as it is today.

Complete list of the blogs followed by Ugo Bardi on June 8, 2020

1. BarneyPanofsky
2. Climalteranti
3. Deric Bownds' MindBlog
4. Il Disinformatico
5. Kelebekler Blog
6. George Monbiot
7. MedBunker
8. Mondi sommersi
9. MondoElettrico
10. New Ice Age
11. Question Everything
12. Resource Insights
13. scienzeedintorni
14. The Club of Rome
15. The Oil Crash
16. xkcd.com
17. Our Finite World
18. Diario di un volatile etnologo
19. Jeremy Leggett
20. The Automatic Earth
21. Richard Heinberg
22. Climatemonitor
23. HotWhopper
24. The Vineyard of the Saker
25. Watts Up With That?
26. Green Tea and Velociraptors
27. Peter Turchin
28. Lucifero Vocifero
29. Madam Mayo
30. Saturday Morning Breakfast Cereal
31. Caitlin Johnstone
32. Moon of Alabama
33. Énergie et environnement
34. Professor Jem Bendell
35. Backreaction
36. The Inquisitive Biologist
37. Kevin Hester
38. Vers où va-t-on ?
39. Wittgenstein
40. What'sUpWithThatWatts, et al.
41. RealClimate
42. alexandra morton
43. Gaianism
44. ROARS
45. Climate Etc.
46. War Is Boring
47. The Center for Humans & Nature Blog
48. Roy Spencer, PhD.
49. Port Sherry
50. Sein oder Nichtsein... To be or not to be...
51. The Blogmire
52. Son of GeekTalk
53. It's About Empathy
54. Silvia Kuna Ballero
55. Clive Best
56. Mirko Busto
57. Geopolitica
58. Gefira
59. Paul Cudenec
60. Jon Rappoport's Blog
61. Just World News
62. The Grumpy Economist
63. Hector Drummond Magazine
64. Shadow Government Statistics
65. Philip Greenspun’s Weblog
66. The Doomstead Diner

It is a mishmash of some 66 blogs, not far from the "Dumbar Number," the number of people with whom one can maintain stable social relationships. It is a list that, most likely, won't make any sense to you, but it does to me. It changes all the time, but it maintains a "core" of blogs that I have been following for several years. "The Old Reader" doesn't allow alphabetic ordering the links, so the list starts with the blogs I have been following for a long time, those at the bottom are new entries (or re-entering the list after a hiatus).

So, what am I reading? You may notice that I am following some of the most subversive blogs of the Web: the pro-Russian Saker, the neo-Eurasianist site of Alexander Dugin, the ultra-communist site of Caitlin Johnstone, and the very subversive "Moon of Alabama." But take into account that I can't avoid being exposed, at least a little, to the standard mass media. So, I am not unaware of what's being said in the mainstream debate. But I can tell you that every time I open the site of a major newspaper, or of CNN, or of RT, I am surprised by the shallowness and the poverty of the information they provide (and not just that, you know better than me that they lie most of the time). And it helps little to try to balance what you read on CNN and RT: averaging two lies doesn't generate a truth.

Then, there are several scientific blogs I follow. Some are rather catastrophistic, such as the ones by Jem Bendell, by Gail Tverberg, or by Antonio Turiel (The Oil Crash). But I also tend to follow a good number of "climate denialist" sites, such as the arch-evil site of Alan Watts (Watts Up With That). Indeed, they are evil, but in a certain way funny. And I learn a lot from their posts. I also follow Roy Spencer, though I disagree with him, he is still a valid scientist. The site kept by Judith Curry is normally boring, but it often provides interesting links. I also follow the Italian "New Ice Age," they are totally cocoa bananas and, fortunately, they don't seem to be so active anymore. But they made death threats against me in the past, so I'd better keep track of what they are up to.

Then, there is a group of blogs that I consider as true gems, but not easily classifiable in political or scientific terms, such as the Kelebekler blog (in Italian), the Empathy site by Chuck Pezhensky, the Gaianism site by Eric Assadurian, the Blogmire by Rob Slane. And many other blogs in different languages, it is truly a zoo. Over the years, I found that I often tend to follow blogs I disagree with. The only kind I can't possibly stomach are those promoting racism, violence, suprematism, oppression, intimidation, and the like -- sorry, those won't make it to my list.

So, what do you think? Are these blogs harming my mental sanity? Maybe. For sure, many people tend to think that I am "strange," especially those who watch TV every day and, if you read the Cassandra blog, you probably understand why. I am hard to classify as being "left" or "right." I don't even fall into the category of the "catastrophists" because I believe that collapse can be reversed. That seems to anger some people who are convinced that it is a good thing that we are all going to die very soon. But, frankly, I am not in a hurry.

There is more, but I don't think you are especially interested in my personal blog preferences. I just wanted to point out to you what I believe is a better way to manage your information bubble. You may give it a try! And if you have stories, comments, or suggestions on information bubbles, we can discuss the subject in the comments.

21 Years Ago: The end of the Bombing of Serbia. And the Start of the Decline of the Western Empire

Nato Bombing of the city of Novi Sad, Serbia, 1999 (image from Wikipedia)

21 years ago, on June 10, 1999, the NATO campaign against Serbia ended after 78 days of bombing. We still don't know exactly the number of victims, civilian and military, nor the amount of damage and it would be difficult to say who actually "won" the bloody mess. But the bombing of Serbia was a turning point for many reasons.

In 1991, the collapse of the Soviet Union marked the end of the "cold war" and gave rise to expectations of a "peace dividend" once the old enemy of the West had folded out. Needless to say, that never happened. It appeared clear with the Serbian campaign that saw the whole Western world allied against a single state of less than 8 million inhabited.

There was nothing special in the Western Empire taking an aggressive posture after the fall of the rival Soviet Empire. It is the way empires work: they are military organizations dedicated to shifting economic resources from the periphery to the center. So, empires last as long as the cost of their huge military apparatus can be paid for by the resources they can control. Since resources are never infinite, they tend to be overexploited and empires suffer of a classic economic problem: diminishing returns. That's the reason for the cycles of growth and collapse of empires in history.

One peculiarity of empires is their capability to mask their mechanisms of operation. After the end of WW2, the Western Empire had managed to paint itself as a "non-empire," a force for the good of humankind. Within some limits, it was not wrong: The Imperial Government in Washington did a lot to rebuild Western Europe, to restore peace and justice, to promote democracy, to keep in check the rival Soviet Empire. Up to the 1990s, it was still possible to believe that, although it required a certain degree of faith.

We can say that the turning point of the way the empire presented itself was the bombing campaign of Serbia. With the best of good will, the idea of "humanitarian bombing" sounded hollow and absurd, no matter how many times it was repeated by the mainstream media. The bombing of the Chinese Embassy of Belgrade, on May 7, 1999, was the turning point in the perception of the campaign. Perhaps, it was also the turning point that led to the end of the bombing about one month later.

Again, no big surprise: the declining trajectory of empires in history starts when their propaganda ceases being believable -- and believed. It had to happen, and it did. It is the moment when the empire starts discovering that it is not so mighty as it believed to be. It is when the imperial coffers start being emptied by the gigantic expenses of keeping alive a monstrously overgrown military machine that has become not only too expensive but also obsolete.

21 years after the end of the Serbian campaign, we have moved to a point in which the decline of the Western Empire is evident. Mr. Trump as a noisy and despised emperor who seems to be unable to keep the empire together among external and internal problems. The main problem may simply be that the Empire is not believable anymore as a force of justice and democracy. There is nothing that can be done about that, it is history moving onward. And we all move with it

Was the Lockdown Effective in Stopping the Spread of the Coronavirus? The Aztec Dilemma

This post was inspired by a post by Chuck Pezeshki on the Aztec civilization, highly recommended as an introduction. 

Scene: Inside the temple at the top of the great pyramid of Tenochtitlán

Characters: the ArchPriest (Master) and the Young Priest (Prentice)


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Prentice: Grand Master, where are you? (walks around, looking). Grand Master?

Grand Master:  Uh...? Prentice, is that you?

Oh... there you are, Master. It's me. Yes. I am sorry to disturb you when you are praying, but...

Hmmmm... I was taking a nap. What's happening?

Master. I need your advice.

Ah...?

See, Master. The time of today's sacrifice is coming.

Yes, of course, I know... I know. We have to start preparing. I must have my obsidian knife somewhere.... By the fangs of of Xipe Totec, it is already getting dark. We have to prepare. . . 

Master, you see, I wanted to tell you something.

Ah...?  Yes, Prentice. We still have some time. But where the Xochiquetzal is my obsidian knife.....

Master, I have a problem....

Oh, yes, here it is. Good old knife... So many hearts I took out with it! But what were you saying, Prentice?

Master, I was thinking of something.

Hmmmm.... Now I need my Mictlantecuhtli mask, should be around. And what have you been thinking?

Master, we always say that if we don't sacrifice a person every day to the sun god Huitzilopochtli, the sun will stop moving in the sky.  

Eh... yes.... that's the point of the ritual of the human sacrifice, of course. You studied that during your training. But where the heck is that mask....

Master, how do we know that?

How do we know what?

That the sun' won't rise tomorrow if we don't perform the sacrifice.

Prentice, you are a smart boy. You know that the god Huitzilopochtli appreciates our sacrifices. And that's proven by the fact that the sun rises every morning. What the great Xochiquetzal have you been thinking? 

Thinking that, well, what if we skip it?

We skip what?

The sacrifice, master.

We skip the sacrifice? Are you mad, Prentice?

No, Master, listen to me. I mean, have we ever missed one of those evening sacrifices?

Prentice, we have always been sacrificing at least one prisoner to the sun God every evening, and the Sun has always risen the morning after. 

That's what I mean, Master. We could skip the sacrifice for once.

Uh.....?

See, I have always been wondering why we never tried that.

Hmm......
 
I mean, of course, I know that if we don't perform the sacrifice, the sun won't rise tomorrow morning. Then, people will be scared. But then we do a few more sacrifices and the sun comes back. Don't you think that the people will be happy? 

 Ah... here is my Mictlantecuhtli mask. I needed it.

Master, what are you thinking of my idea?

Prentice, listen to me. 

Yes, Master?

Prentice, you know that the fact that the sun is coming out every morning is proof that the sacrifices work. 

Yes, Master, I know that. But, actually, you see, I thought that, maybe, we could do a test. . .

Prentice. I always said you were a good boy. Now, suppose we don't sacrifice tonight, as you propose. What if the sun comes up anyway tomorrow morning?

Master, that cannot be. The sun god will be awfully angry and. . . .

Just suppose that, you idiot!

Ah.... well, Master. But you taught me. . .

Never mind what I taught you, you dumbfuck moron. You know what would happen. The people of Tenochtitlán would climb this stupid pyramid, then cut our hearts out and eat them. 

Master, but I am sure that the god Huitzilopochtl wouldn't push the sun out if we don't perform the sacrifice.

Sure, Prentice, sure. But now, I have a good idea. I go to organize the sacrifice for tonight. You stay here until I come back.

Master, but I should help you with the preparations...

Stay here, I said.

Master, but why....?

Just stay here and wait, Prentice. And thanks for volunteering for tonight's sacrifice.

Epidemiological Models: A Simple Explanation of How they Work

There is a certain logic in the way the universe works and so it is not surprising that the same models can describe phenomena that seem to be completely different. Here, I'll show you how the same equations describe chain reactions that govern such different phenomena as the spread of an epidemic, the cycle of extraction of crude oil, and even the nuclear reaction that creates atomic explosions. All these phenomena depend on the efficiency of energy transfer, the parameter that's known in energy studies as EROI (energy return on energy invested), related to the "transmission factor" (R) of epidemiological models. Above, a classic clip from Walt Disney's 1957 movie, "Our friend, the atom." 

You may be surprised to discover that epidemiological models share the same basic core of peak oil models. And it is not just about peak oil, the same models are used to describe chemical reactions, resource depletion, the fishing industry, the diffusion of memes on the Web, and even the nuclear chain reaction that leads to nuclear explosions. It is always the same idea: reinforcing feedbacks lead the system to grow in a frenzy of exploitation of an available resource: oil, fish, atomic nuclei, or people to be infected. In the end, it is perhaps the most typical way the universe uses dissipate potentials. As always, entropy rules everything!

Modeling these phenomena has a story that starts with the model developed in the 1920s by Vito Volterra and Alfred Lotka. They go under the name of "Lotka-Volterra" models or, sometimes, "Prey-Predator" models. This heritage is not normally recognized by people in the field of epidemiology, but the model is the same: the virus is a predator and we are the prey. The only difference is that an epidemic cycle is so short, typically a few months, that the prey, people, don't reproduce during the cycle. Then, if you think that oil companies are predators and oil fields are the prey, then we have again the same model. Finally, you can see the atomic chain reaction that takes place during fission as generated by neutrons acting as predators and atomic nuclei acting as prey. In the Walt Disney interpretation, shown in the clip above, ping-pong balls are the predator and mousetraps are the prey.

 

To describe the model, let's focus on epidemiology. These models are called "SIR," with the acronym standing for "Susceptible, Infected, Recovered." The idea is that the Infected stock grows proportionally to both the Susceptible and the Infected stocks -- it is a feedback loop. No feedback, no growth, this is how these models work. Then, of course, the virus will gradually run out of susceptible people, growth will slow down and, eventually, the infected stock will start declining. Then, the epidemic will be over.

So, let's see what the model produces in its simplest version. I made it using the Vensim (TM) system dynamics package (see at the end of the post for the details *)

Note how the number of susceptible people (blue curve) gradually declines. Instead, the number of cases per unit time (green curve) and the total infected people (red curve) show a cycle of growth and decline. Finally, the recovered people (gray curve) grow and then stabilize. (they might also die, the equations won't change.)

Let's compare with peak oil models: the names of the variables change, but the model is the same

Susceptible  --> Oil Resources

Infection rate --> oil production
Infected --> Extracted Oil
Recovered --> Pollution

Note the green curve in the figure. It is symmetric and bell-shaped: it is the typical "Peak Oil" curve. In the case of oil, the curve describes the production in barrels per day. In the case of an epidemic, it describes the number of new cases of infections per day. The curve for the victims should be the same, but (hopefully) smaller and shifted forward in time to take into account that you die after having contracted the virus. The red curve in the figure is proportional to the amount of oil extracted and not yet burned. It is the "capital" of the oil industry. As oil is burned, it becomes pollution and disappears from the model 

You can play the same game with other phenomena. For instance, in the case of the "mousetrap model" developed by Disney studios, the one shown in the clip at the beginning of this post, you have that

Susceptible --> trapped balls
Infection rate --> number of traps springing per unit time.
Infected --> number of flying balls
Recovered --> balls on the ground

In general, epidemiological models are normally much more complicated than the basic SIR model that I showed above. That is, in my opinion, a weakness of these models. Attempting to evaluate such parameters as how many people will contact each other per day, and from that estimating the infection rate is nearly hopeless and, indeed, these models have a poor record in terms of quantitative forecasting. Even peak oil models, although not so bad, turned out to be unsuccessful in estimating the data of the peak, at least in terms of volumes of liquids produced.

But this is a long story and I won't get into it, here. Let me just say that, in general, models may be useful even (and perhaps especially) when you don't ask them to make exact predictions. Often, a correct warning may be much more useful than an incorrect prediction. That's true when the models are well-grounded in physics and can tell you what will happen, even though not necessarily when.

Something that you can learn from these models is how the behavior of the system is determined by an efficiency parameter called R in epidemiology and EROI (energy return on energy invested) in peak oil studies. Yes, these two parameters are the same -- apart from some details. They share the property that they need to have a minimum value in order for the chain reaction (the epidemics or a cycle of extraction) to start. In epidemiology, you can show that R must be >1 for the infection to grow. As the epidemic proceeds, R becomes smaller. When R=1, you have the "peak virus" and the number of infected people starts declining. That's called "herd immunity."

Things are not so simple for the peak oil curves, but the story is the same. You can show that an energy-producing resource cannot be produced with a positive energy yield unless you have EROI=1/η at the beginning of the extraction cycle, with η the efficiency of the transformation of the energy of the extracted resource into useful energy (exergy). For crude oil, we may probably take η as equal to 0.1-0.2. The implication is that oil extraction is not viable for EROI<5-10, which is consistent with the current situation. We are close to EROI values that correspond to an unavoidable decline of the industry. (Note that this condition is for "peak capital" -- "peak oil" comes for even larger values of the EROI)

Ah... by the way, these limits of the EROI values are valid only for exhaustible resources such as crude oil. They do not hold for renewable energy sources such as solar energy -- of course, you can't run out of sunlight!
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The R and the EROI parameters of chain reaction models -- a quick explanation


Ro is defined as the expected number of cases generated by one case in a population where all individuals are susceptible to infection, that is, at the initial stages of the epidemic. As the epidemic proceeds, varying proportions of the population become immune. To account for this, the "effective reproduction number" is used, written as Rt or simply R. It is the average number of new infections caused by a single infected individual at time t. When the fraction of the population that is immune increases so much that R drops below 1, it is said that "herd immunity" has been achieved. It means that the number of infected people does not grow any longer and gradually decreases toward zero.

The EROI (or EROEI) (energy return of energy investment) factor in oil extraction is defined as the number of barrels of oil produced using the energy obtained from one barrel. It is more general than that, but let's remain with crude oil. Obviously, when the EROEI goes below one, the whole enterprise of oil extraction becomes useless in terms of producing useful energy. But "peaking" of oil production starts well before the EROI goes below one, as we'll see in the following.

R and EROI look similar and, indeed, they are the same thing. To say something more about this matter, we need to write down the equations of the model. Here they are for the SIR system, with S=susceptible, I=infected, and R= recovered

dS/dt = - k₁SI

dI/dt = k₁SI  - k₂I

Note that the coefficient k₁ is the same in both equations because the number of people who become infected is equal to the number of those who cease being susceptible -- these two coefficients won't be the same in the equivalent equations for oil extraction. The other coefficient, k₂, is the frequency of recovery of the infected people. There is a third equation describing the growth of the "recovered" stock, but it is simply equal to k₂I and we can neglect it here. 

Now, from the equations above, we can say that the R factor is equal to the number of new infections divided by the number of infected people. We need to take also into account the recovery frequency: the gradual disappearance of people from the "infected" stock. So that the result is:

R=  Sk₁/k₂

Note that the variables in this model are usually expressed in terms of fractions. So, the number of susceptible people at the very start of the epidemic is supposed to be 100% of the population, that is, unity. There follows that

Ro= k₁/k₂

Now we can determine the value of R needed for attaining "herd immunity." the value needed for stopping the growth of the infection. For this, we take the second equation of the two of the model. We want to know when the number of infected people, I, starts to decline. That means to find when dI/dt <0. That is:


k₂R-k₂ <0

Or, R<1.  

This is the condition for herd immunity. It explains the attention dedicated to this number for the current coronavirus epidemic. 

Measuring R may be a good idea but, in reality, it is not a very useful way to forecast the trajectory of an epidemic. To measure R you need to know S, but normally you don't know who is susceptible and who is not unless you try to infect them. So, saying that "R has become smaller than one" is the same thing as saying that "the number of infected people in the population has started declining." And the latter term is what you can actually measure or, at least, estimate. As someone said, "Models are accurate only when they become irrelevant."

How about the EROI? The equations are the same, but with a small difference. Whereas people move quantitatively from the "Susceptible" to the "Immune" stock, transforming a unit of energy embedded in underground oil into a unit of usable energy cannot be 100% efficient. So, you need another coefficient in the equations, a "transformation efficiency", η as a coefficient of k1 in the second equation. Obviously, it must be that η<1 because of the 2nd law of thermodynamics.

We go through the same mathematical tricks and we find the condition for the amount of stored energy (the "capital" of the industry) starts declining. It has to be:

EROI < 1/η

For the transformation of crude oil into useful energy into a thermal engine, we can roughly estimate a life cycle efficiency of the order of 10%-20%. There follow that oil extraction is not thermodynamically viable for an EROI < 5-10, which agrees with independent estimates of EROI for crude oil. It was probably around 30 during the early stages of exploitation and therefore allowed the industry to grow. Currently, the average EROI for oil extraction is probably around 10-15, so that we are close to the start of the irreversible decline of the industrial system that exploits it. Or, it may have already started. 

Note that the condition EROI < 1/η does NOT correspond to "peak oil" as it is normally defined. It is, rather, "peak capital". Peak oil refers to oil production, which is not the same thing. But it is not possible to find an equivalent simple expression that correlates the EROI of the system with the occurrence of the peak. We can only say that it occurs earlier and, therefore, for larger values of the EROI.


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(*) Here is the Vensim model I used for the graph shown in this post. If you want the code, just write to me.