Scientific "measurements"....

From Torah Explorer by Yoram Bogacz

Chromium Opprobrium

December 18, 2017

https://torahexplorer.com/

Perhaps the most serious error that contemporary society makes about science is that all its results are equally credible. One of the main themes of Genesis and Genes is that science operates on different levels; results in some realms of science are credible, while results in other areas should be treated with considerable scepticism. In particular, one should be wary of claims about events that allegedly occurred millions or billions of years ago and are not amenable to direct observation.
This is a point that is misunderstood not only by the vast majority of laymen, but also by professional scientists. Here is an excerpt from Genesis and Genes.
[Beginning of excerpt]
With this in mind, let us consider this statement by a contemporary scientist and author:

Radioactive carbon-14 had a 5600-year half-life in the early universe just as it has now.^[1]

This is the voice of faith. The truth is that we do not know and cannotknow the half-life of carbon-14 in the early universe. We were not there, and any conclusions made on the basis of current measurements, no matter how plausible, will be based on assumptions about how nature’s laws operated in the past. Often, these assumptions are left unstated, so that the public is convinced that measurement of the cosmic background radiation, for example, is a direct measurement of some parameter that characterised the early universe. It isn’t. The theory from which the measurements derive their importance assumes, at the very least, that certain laws of nature operated at specific rates throughout the past, all the way back to the beginning. We shall never know whether this assumption is justified. Nonetheless, many contemporary scientists are committed to the principle of the immutability of natural laws. Whatever laws are operative today, they maintain, have always operated, and always at the same rate.
[End of excerpt]
One of the most important parameters in Origin-of-Life research is the atmospheric concentration of oxygen. All models that deal with the emergence of life on Earth rely on conclusions about how much oxygen our atmosphere contained at various points of Earth’s history. One reason for this, of course, is that large mammals like human beings need a high concentration of atmospheric oxygen to “operate”. A second reason is that too much oxygen in the atmosphere would lead to spontaneous fires erupting everywhere, not a scenario guaranteed to provide comfort to any emerging life. But perhaps the most important point is that oxygen, being a reactive (that is, destructive) molecule, makes it immensely unlikely that delicate organic reactions could have happened in the remote past. Abundant atmospheric oxygen would simply have wrecked these fragile processes before they had a chance to even begin.
So, how do you measure the atmospheric concentration of oxygen in Earth’s atmosphere billions of years ago? Not surprisingly, the answer is, “With great difficulty.” One of the standard techniques involves measuring the ratio of two isotopes of the metal Chromium in ancient rocks. [Isotopes are versions of the same element; every atom of the element has the same number of protons in its nucleus, but different isotopes contain different numbers of neutrons.]
New research sheds interesting light on the possible pitfalls in this kind of research.^[2] A report about research done at the Georgia Institute of Technology begins with the following paragraph:

For researchers pursuing the primordial history of oxygen in Earth’s atmosphere, a new study might sour some “Eureka!” moments. A contemporary tool used to trace oxygen by examining ancient rock strata can produce false positives, according to the study, and the wayward results can mask as exhilarating discoveries.

What is going on? The article continues:

Common molecules called ligands can bias the results of a popular chemical tracer called the chromium (Cr) isotope system, which is used to test sedimentary rock layers for clues about atmospheric oxygen levels during the epoch when the rock formed. Researchers at the Georgia Institute of Technology have demonstrated in the lab that many ligands could have created a signal very similar to that of molecular oxygen.

In other words, you think you’re measuring A, but in reality B is interfering and giving you results that mislead you. The result is

“There are some geographical locations and ancient situations where measurable signals could have been generated that had nothing to do with how much oxygen was around,” said Chris Reinhard, one of the study’s lead authors.

This is not just theory. The article states,

But some researchers confronted with odd Cr signals have thought they had perhaps stumbled upon a radical find, and they developed explanations for how O2 [oxygen] may have been surprisingly bountiful on the lonesome spot where a particular rock layer formed, while molecular oxygen was scant on the rest of the globe. Others puzzled that atmospheric O2 levels may have risen much earlier than overwhelmingly broad evidence has indicated.

“A lot of that could be chalked up to other chemical processes and not to interactions with oxygen,” Reinhard said.

&&&

There are at least two important conclusions to draw from this research. Firstly, when you read popular accounts of scientific research, words like measure pop up frequently, and provide a misleading impression of the process used to obtain the results. Very often, research does not directly measure whatever quantity the scientists are after. Rather, there is a proxy that is believed to serve as a reliable marker for the desired quantity. What the public fails to appreciate, however, is that the line between the proxy and the desired quantity is not straight; it is not even a line. It is a convoluted and intricate curve, and it is vulnerable to many obstacles.
Dr. Gerald Schroeder often confuses the proxy and the desired quantity in Genesis and the Big Bang. Here are typical statements from his book:

Cosmologists measured the age of the universe…; The age of the universe has been measured using a variety of independent… systems; …Phenomena that are readily measurable by modern archaeological, paleontological and cosmological instrumentation;

These remarks are phenomenally misleading. The supposed measurement that is spoken of here consists of numerous intricate steps, each of which depends on its own assumptions and is subject to unstated pitfalls.
This is precisely what you see in the Georgia Tech study. Popular accounts of this type of research omit the necessary caveats, and describe scientists as measuring the concentration of atmospheric oxygen. They do no such thing. There is a complicated process which is believed to reflect the desired quantity. If one understands this, and is aware of how often proxies turn out to be unreliable indicators of various quantities, the credibility of such reports is considerably diminished.
The second major lesson to take home is that – surprise! – science is not infallible. Until the research at Georgia Tech, nobody was aware that ligands could mimic the effects of various isotopes of chromium and thereby throw off the researchers. As the article makes clear, “some researchers confronted with odd Cr [chromium] signals have thought they had perhaps stumbled upon a radical find, and they developed explanations for how O2 may have been surprisingly bountiful on the lonesome spot where a particular rock layer formed…”
All sorts of theories and conclusions flowed from various findings which, in hindsight, turn out to be mistaken. Informed consumers of science would do well to adopt a more sceptical stance towards origin-of-life research.
SOURCES:
[1] Genesis and the Big Bang, Gerald L. Schroeder, Bantam Books, paperback edition 1992, page 29.
[2] http://www.rh.gatech.edu/news/598840/popular-tool-trace-earths-oxygen-history-can-give-false-positives. Last retrieved 18^th December 2017.

Textbook Wisdom on Human Origins Is Wrong!

Günter Bechly

December 12, 2017, 1:03 AM

https://evolutionnews.org/2017/12/its-official-textbook-wisdom-on-human-origins-is-wrong/

In three earlier articles at Evolution News (Bechly 2017a-c), I’ve written about the numerous paleoanthropological discoveries this year that generated media headlines announcing one “rewrite” of human evolution after another. I hardly dared to dream that, as an early Christmas present, 2017 would close with a final blow to the Out of Africa story. Yet guess how Discover Magazine announced this latest development? That’s right: “It’s Official: Timeline for Human Migration Gets a Rewrite” (Tarlach 2017).

As the article demonstrates, even mainstream paleoanthropologists now acknowledge that there is a problem with the ruling paradigm on human origins and with the way scientists have handled the accumulating evidence against it. We read:

The wealth of new paleoanthropological, archaeological and genetic evidence has passed the tipping point: In a review published today in the prestigious journal Science, researchers acknowledge that the conventional timeline of human migration out of Africa “can no longer be considered valid”….

Unfortunately, many researchers clung to the idea of a single migration out of Africa, no earlier than 60,000 years ago, for too long. Finds such as a human presence in the Levant 100,000 years ago, for example, were dismissed…

Today, however, writing in Science, researchers say that no one can ignore the preponderance of evidence. It’s time, at long last, to revise that tired old timeline of human migration.

The article in Science, Bae et al. (2017), states in unambiguous terms:

A rigid definition of the OoA model positing that modern humans dispersed from Africa only after 60 ka and simply replaced all indigenous populations…with no interbreeding can no longer be considered valid.

The rewrite, though, is not the necessary rethink we may have hoped for (Bechly 2017c). Instead we find the usual fudging on the conventional story, with the minimal changes required to accommodate the conflicting evidence. Darwinian just-so stories are reconsidered, but Darwinism itself may not be questioned.

Nevertheless, Gemma Tarlach, writing for Discover, comments critically:

Okay, so, science solved that, thanks, we know everything now, right? Nope. The new timeline for human migration still has some big holes to fill. Let’s start with where our species evolved.…

Our birthplace remains a mystery. Also big questions: how the first modern H. sapiens left Africa and where they went….

Acknowledging that our Out of Africa saga has many chapters stretching farther back in time is an important advance for the field. But some paleoanthropologists are unlikely to sign on: that small but vocal group of researchers who advocate a regional model for our species’ evolution….

So, while the conventional timeline that has dominated for half a century finally takes a tumble, don’t think that this is the end of the great debate regarding the early days of our species.

Who said it all along, yet was ridiculed by incompetent Darwinist bulldogs (e.g., Needle 2017) on the Web? Yes, indeed, you read it here first.

Literature:

• Bae CJ, Douka K, Petraglia MD 2017. “On the origin of modern humans: Asian perspectives.” Science358(6368): eaai9067.
• Bechly G 2017a. “Fossil Footprints from Crete Deepen Controversy on Human Origins.” Evolution News, September 6, 2017.
• Bechly G 2017b. “Human Origins: Out of Africa, or Out of Germany?” Evolution News, October 23, 2017.
• Bechly G 2017c. “What, Another ‘Rewrite’ of the Human Origins Story? How About a Rethink, Instead?” Evolution News, November 20, 2017.
• Needle B 2017. “Bechly belches!” Marmotism, October 28, 2017.
• Tarlach G 2017. It’s Official: Timeline for Human Migration Gets a Rewrite. Discover Magazine, December 7, 2017.

Why Is Giving Birth So Hard?

New theories are challenging a long-standing notion that the difficulty of childbirth is simply an evolutionary trade-off.

A newborn is examined at a maternity ward in England.Suzanne Plunkett / Reuters

·      JOSIE GLAUSIUSZ

·       DEC 4, 2017

·       HEALTH

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Harvey Karp, the best-selling author of The Happiest Baby on the Block, has some advice on his website for frazzled new parents: “Remember—your baby’s brain was so big that you had to ‘evict’ her after nine months, even though she was still smushy, mushy, and very immature.”

It’s not an idea unique to Karp. Scientists have long struggled to explain the myriad challenges attending human childbirth compared to other primates, from the relative helplessness of human infants, to the very “tight fit,” as some researchers have put it, between the female human pelvis and the typical size of a child that must pass through it.

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The mystery was the catalyst for what became known as “the obstetrical dilemma,” a long-debated though widely accepted hypothesis suggesting that the upright gait of Homo sapienswas accompanied by a narrowing of the pelvis—an evolutionary trade-off that resulted in increased risks to pregnant mothers as they struggled to push large-brained babies through ever-slimmer birth canals. Among other things, the dilemma has been used to suggest that the wider, birth-giving hips of women have hindered them locomotively and athletically—and perhaps even evolutionarily—compared to men.

That has always struck some scientists as too pat an explanation, though it is only in the last decade or so that the theory, which still has many subscribers, has received substantive pushback. Today, challenges abound for the idiosyncrasies of human gestation and birth—including new notions that look beyond evolution to more proximate and modern factors like poor diet and obesity.

Of course, rigorous debate over the relative strengths and weaknesses of theories in this cul-de-sac of physiological science will surely continue. But for all the back-and-forth, one thing seems quite clear: The days of simply describing the human birth process—and women themselves—as evolutionarily compromised seem to be coming to an end.

For some researchers, that change in thinking is long overdue.

* * *

Sherwood Washburn, the physical anthropologist who coined the phrase“obstetrical dilemma,” first published his theory in the September 1960 issue of Scientific American. He argued that, “in man, adaptation to bipedal locomotion decreased the size of the bony birth canal at the same time that the exigencies of tool use selected for larger brains. This obstetrical dilemma was solved by the delivery of the fetus at a much earlier stage of development.”

Early delivery, he concluded, foisted far greater responsibility on the “slow-moving mother,” who was now forced to hold her “helpless, immature infant,” while the men went out hunting.

The assumption that “women are compromised bipedally in order to give birth,” is widely accepted, says anthropologist Holly Dunsworth of the University of Rhode Island. But Dunsworth sees flaws in this premise. Women already have a range of dimensions in their birth canal, she thought, and they are all walking just fine. Indeed, research on human skeletons by anthropologist Helen Kurki of the University of Victoria in Canada has shown that the size and shape of the human birth canal varies very widely, even more so than the size and shape of their arms.

So in 2007, Dunsworth went looking for evidence to support the obstetrical dilemma as it has traditionally been understood.

“When I couldn’t, I thought I was crazy,” she says. Intrigued, she enlisted Anna Warrener, a professor of biology and biomechanics, then at Harvard University, to test the notion that wider pelvises in women decrease the efficiency of locomotion. After measuring the chain reaction of forces moving through the body—from the foot to the leg to the hip—Warrener and her colleagues found that wider hips do not increase the cost of locomotion. Indeed, both women and men are equally efficient at walking and running, and in hunter-gatherer societies, women walk, on average, 5.5 miles per day, often while carrying and feeding infants as well.

“The obstetric dilemma, in its definition, has housed this idea that women aren’t as good as men in some things because they have to give birth,” adds Cara Wall-Scheffler, an evolutionary anthropologist who studies human locomotion at Seattle Pacific University. “I have a number of papers that show that women are great walkers, and in some particular tasks women are better—they don’t use as much energy, they don’t build as much heat, they can carry heavier loads with less of an energetic burden.”

Dunsworth has an alternative theory as to why human pregnancy ends when it does: It’s called EGG, for “energetics of gestation and fetal growth,” and it applies not just to humans but to other mammals too. While a mother’s metabolic rate doubles during pregnancy, the fetus’s energy needs to increase exponentially toward the end of pregnancy. “As the fetus gets bigger and bigger and costlier and costlier to grow inside of the uterus,” Dunsworth explains, the mother’s metabolic rate reaches a limit. But the baby has to continue growing, “so the only way to do that is to get born.”

She is currently testing EGG on pregnant marmosets, measuring their energy use and metabolic rate during pregnancy over time, “to see if they give birth when they reach their maximum sustainable metabolic rate, as we do.”

Still others seek to explain why human brain volume has tripled over the past 2.5 million years, from the time of the Australopithecines. In a 2016 paper, brain and cognitive-science researchers Steven Piantadosi and Celeste Kidd of the University of Rochester argue that helpless, larger-brained but early-born babies select for parents with advanced intelligence who must interpret their wordless signals; these larger-brained parents produce babies with ever-increasing brain size, a self-reinforcing process leading to “runaway selection for premature infants and big brains.”

Dunsworth readily acknowledges that childbirth can be difficult, and that the human birth canal is indeed a tight fit for the fetus, even though humans are born with the smallest relative brain of all primates (only 30 percent of our adult brain size, compared to chimps, whose brains at birth are 40 percent of adult size). Globally, an average of 216 women die for every 100,000 live births, according to data from UNICEF. But the disparity between high- and low-income countries is gigantic: The lifetime risk of maternal death in rich countries is one in 3,300, compared to one in 41 in poor countries.

As such, blaming reproductive complications on evolution, writes Pamela K. Stone of the Culture, Brain, and Development Program at Hampshire College in Amherst, Massachusetts, “conceals the larger health disparities and risks that women face globally.”

Childbirth is difficult for many reasons, she writes—among them the 19th-century switch from birthing in the upright position, which allows the pelvic girdle to expand in response to contractions, to the supine position (still common among women in the West) which often requires the use of forceps.

* * *

Enter Jonathan Wells, a professor of anthropology and pediatric nutrition at the Great Ormond Street Institute of Child Health at University College London, who argues for a competing hypothesis on the obstetrical dilemma. For starters, Wells argues, long-term ecological trends have likely played a role in changes in both pelvic dimensions and offspring brain size. One such trend was the rise of agriculture about 11,500 years ago in the Levant, which led to a shift from a high-protein diet common among foragers to one replete with cereals. A high-carb diet is associated with both increased birth weight and shorter stature in the mother, and short stature is linked to smaller and flatter pelvises.

By that reasoning, the emergence of agricultural diets could have impacted “maternal mass and brain size, and may therefore have exacerbated the obstetric dilemma,” he says.

More recently, Wells has pointed to trends in both malnutrition and obesity as culprits in what he describes as a “new” obstetrical dilemma. According to Wells, this “dual burden” is contributing to a rising toll of obstructed labor, gestational diabetes, and larger-than-average newborns. Wells describes his theory in the April 2017 issue of The Anatomical Record.

Between 1980 and 2013, the percentage of overweight and obese women globally rose from 29.8 percent to 38 percent. At the same time, one in three people are malnourished in one form or another. “There is rapidly accumulating evidence,” Wells says, “that the dual burden of malnutrition can occur within the same individuals: those who experienced poor nutrition and became stunted in early life, but who have also been exposed to obesogenic pressures from childhood onward and who have therefore gained excess weight subsequently.”

As Wells notes, obstructed labor, where delivery of the baby causes harm to the mother, child, or both, accounts for 12 percent of maternal mortality worldwide. It also increases substantially the risk of serious long-term maternal injuries, such as obstetric fistula. Dunsworth’s EGG theory can’t explain this frequency, he says.

But the combination of obesity and malnutrition can: Malnutrition and infectious disease in childhood is linked to short stature, which is associated with smaller pelvises in adulthood. Obesity, which is rising fastest in populations most prone to childbirth complications, increases the risk of delivering a “macrosomic” baby, whose birth weight exceeds the 90th percentile in any given population. “Overweight women in most populations are more likely to develop gestational diabetes if they are also short,” Wells adds. The combination of gestational diabetes and maternal obesity doubles the risk of macrosomic babies. So in theory, Wells says, a short overweight woman has two different risk factors for obstructed labor: smaller pelvic dimensions, and a higher probability of producing a large newborn.

This scenario is further aggravated by the persistence of child marriage, in which teens give birth before pelvic growth is completed, and gender inequality. A recent study of 31 countries in sub-Saharan Africa conducted by Alissa Koski, a postdoctoral scholar at the University of California, Los Angeles, Fielding School of Public Health, found that more than one-third of girls in more than half of the countries studied married before the age of 18. In another study of 96 countries, Wells and his colleagues found “strong associations” between societal gender inequality and the prevalence of low birth weight, stunting, wasting, and child mortality. “On this basis,” he says, “societies with high levels of gender inequality are more likely to produce adult women of smaller body size,” which will impact the dimensions of the pelvis.

At the other extreme, he notes, obesity is increasing in prevalence faster in women than in men. Given these rapid increases in obesity, overweight women are more likely to experience difficulties in delivering babies if they were also stunted in childhood, Wells predicts—although so far, he doesn’t have the data to prove it. It is clear, however, that cesarean delivery has become one of the most common surgical procedures worldwide, increasing to “unprecedented levels” between 1990 and 2014 and ranging from 6 to 27 percent of all births in the least- to most-developed regions, respectively.

Dunsworth sees this as something of a self-fulfilling prophecy. “I worry that this idea [of the obstetrical dilemma] is justifying status-quo high rates of C-sections and other childbirth interventions,” Dunsworth says. “People say, ‘It’s just evolution—there’s nothing we can do, and here’s how technology helps, and that’s fabulous.’ But I know we’re overdoing it. Everybody knows that.”

While Dunsworth says she admires Wells’s research, she adds that she wishes he would come out a little more strongly against the evolutionary obstetrical dilemma.

For his part, Wells describes the work of Dunsworth and her colleagues as being of “major importance.” But “that doesn’t mean that Washburn had no important message,” he adds. “We have to acknowledge that the process of birth is surprisingly complex in humans, compared to other apes.”

“It is very clear from maternal mortality statistics that the contemporary burden of the obstetric dilemma is highly unequally distributed amongst women,” Wells says. “This suggests that if we had a better understanding of its biological basis, we could improve our efforts to reduce the burden of maternal and child mortality.”

...........science has its limits

Martin Rees

is is a fellow of Trinity College and emeritus professor of Cosmology and Astrophysics at the University of Cambridge. He is the Astronomer Royal and a foreign associate of the US National Academy of Sciences, the American Philosophical Society, and the American Academy of Arts and Sciences. He is the author of more than 500 research papers and eight books.

[[Very excellent article - D.G.]] 

Albert Einstein said that the ‘most incomprehensible thing about the Universe is that it is comprehensible’. He was right to be astonished. Human brains evolved to be adaptable, but our underlying neural architecture has barely changed since our ancestors roamed the savannah and coped with the challenges that life on it presented. It’s surely remarkable that these brains have allowed us to make sense of the quantum and the cosmos, notions far removed from the ‘commonsense’, everyday world in which we evolved.

But I think science will hit the buffers at some point. There are two reasons why this might happen. The optimistic one is that we clean up and codify certain areas (such as atomic physics) to the point that there’s no more to say. A second, more worrying possibility is that we’ll reach the limits of what our brains can grasp. There might be concepts, crucial to a full understanding of physical reality, that we aren’t aware of, any more than a monkey comprehends Darwinism or meteorology. Some insights might have to await a post-human intelligence.

Scientific knowledge is actually surprisingly ‘patchy’ – and the deepest mysteries often lie close by. Today, we can convincingly interpretmeasurements that reveal two black holes crashing together more than a billion light years from Earth. Meanwhile, we’ve made little progress in treating the common cold, despite great leaps forward in epidemiology. The fact that we can be confident of arcane and remote cosmic phenomena, and flummoxed by everyday things, isn’t really as paradoxical as it looks. Astronomy is far simpler than the biological and human sciences. Black holes, although they seem exotic to us, are among the uncomplicated entities in nature. They can be described exactly by simple equations.

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So how do we define complexity? The question of how far science can go partly depends on the answer. Something made of only a few atoms can’t be very complicated. Big things need not be complicated either. Despite its vastness, a star is fairly simple – its core is so hot that complex molecules get torn apart and no chemicals can exist, so what’s left is basically an amorphous gas of atomic nuclei and electrons. Alternatively, consider a salt crystal, made up of sodium and chlorine atoms, packed together over and over again to make a repeating cubical lattice. If you take a big crystal and chop it up, there’s little change in structure until it breaks down to the scale of single atoms. Even if it’s huge, a block of salt couldn’t be called complex.

Atoms and astronomical phenomena – the very small and the very large – can be quite basic. It’s everything in between that gets tricky. Most complex of all are living things. An animal has internal structure on every scale, from the proteins in single cells right up to limbs and major organs. It doesn’t exist if it is chopped up, the way a salt crystal continues to exist when it is sliced and diced. It dies.

Scientific understanding is sometimes envisaged as a hierarchy, ordered like the floors of a building. Those dealing with more complex systems are higher up, while the simpler ones go down below. Mathematics is in the basement, followed by particle physics, then the rest of physics, then chemistry, then biology, then botany and zoology, and finally the behavioural and social sciences (with the economists, no doubt, claiming the penthouse).

‘Ordering’ the sciences is uncontroversial, but it’s questionable whether the ‘ground-floor sciences’ – particle physics, in particular – are really deeper or more all-embracing than the others. In one sense, they clearly are. As the physicist Steven Weinberg explains in Dreams of a Final Theory (1992), all the explanatory arrows point downward. If, like a stubborn toddler, you keep asking ‘Why, why, why?’, you end up at the particle level. Scientists are nearly all reductionists in Weinberg’s sense. They feel confident that everything, however complex, is a solution to Schrödinger’s equation – the basic equation that governs how a system behaves, according to quantum theory.

But a reductionist explanation isn’t always the best or most useful one. ‘More is different,’ as the physicist Philip Anderson said. Everything, no matter how intricate – tropical forests, hurricanes, human societies – is made of atoms, and obeys the laws of quantum physics. But even if those equations could be solved for immense aggregates of atoms, they wouldn’t offer the enlightenment that scientists seek.

Macroscopic systems that contain huge numbers of particles manifest ‘emergent’ properties that are best understood in terms of new, irreducible concepts appropriate to the level of the system. Valency, gastrulation (when cells begin to differentiate in embryonic development), imprinting, and natural selection are all examples. Even a phenomenon as unmysterious as the flow of water in pipes or rivers is better understood in terms of viscosity and turbulence, rather than atom-by-atom interactions. Specialists in fluid mechanics don’t care that water is made up of H₂O molecules; they can understand how waves break and what makes a stream turn choppy only because they envisage liquid as a continuum.

New concepts are particularly crucial to our understanding of really complicated things – for instance, migrating birds or human brains. The brain is an assemblage of cells; a painting is an assemblage of chemical pigment. But what’s important and interesting is how the pattern and structure appears as we go up the layers, what can be called emergent complexity.

So reductionism is true in a sense. But it’s seldom true in a useful sense. Only about 1 per cent of scientists are particle physicists or cosmologists. The other 99 per cent work on ‘higher’ levels of the hierarchy. They’re held up by the complexity of their subject, not by any deficiencies in our understanding of subnuclear physics.

In reality, then, the analogy between science and a building is really quite a poor one. A building’s structure is imperilled by weak foundations. By contrast, the ‘higher-level’ sciences dealing with complex systems aren’t vulnerable to an insecure base. Each layer of science has its own distinct explanations. Phenomena with different levels of complexity must be understood in terms of different, irreducible concepts.

We can expect huge advances on three frontiers: the very small, the very large, and the very complex. Nonetheless – and I’m sticking my neck out here – my hunch is there’s a limit to what we can understand. Efforts to understand very complex systems, such as our own brains, might well be the first to hit such limits. Perhaps complex aggregates of atoms, whether brains or electronic machines, can never know all there is to know about themselves. And we might encounter another barrier if we try to follow Weinberg’s arrows further down: if this leads to the kind of multi-dimensional geometry that string theorists envisage. Physicists might never understand the bedrock nature of space and time because the mathematics is just too hard.

My claim that there are limits to human understanding has been challengedby David Deutsch, a distinguished theoretical physicist who pioneered the concept of ‘quantum computing’. In his provocative and excellent book The Beginning of Infinity (2011), he says that any process is computable, in principle. That’s true. However, being able to compute something is not the same as having an insightful comprehension of it. The beautiful fractal pattern known as the Mandelbrot set is described by an algorithm that can be written in a few lines. Its shape can be plotted even by a modest-powered computer: 

Mandelbrot set. Courtesy Wikipedia.

But no human who was just given the algorithm can visualise this immensely complicated pattern in the same sense that they can visualise a square or a circle.

The chess-champion Garry Kasparov argues in Deep Thinking (2017) that ‘human plus machine’ is more powerful than either alone. Perhaps it’s by exploiting the strengthening symbiosis between the two that new discoveries will be made. For example, it will become progressively more advantageous to use computer simulations rather than run experiments in drug development and material science. Whether the machines will eventually surpass us to a qualitative degree – and even themselves become conscious – is a live controversy.

Abstract thinking by biological brains has underpinned the emergence of all culture and science. But this activity, spanning tens of millennia at most, will probably be a brief precursor to the more powerful intellects of the post-human era – evolved not by Darwinian selection but via ‘intelligent design’. Whether the long-range future lies with organic post-humans or with electronic super-intelligent machines is a matter for debate. But we would be unduly anthropocentric to believe that a full understanding of physical reality is within humanity’s grasp, and that no enigmas will remain to challenge our remote descendants.