Some leading ladies of science

kw: book reviews, nonfiction, short biographies, women, science

My parents knew who Hedy Lamarr was; she starred in more than 20 American films in the 1940s and 1950s, after being a film star in Europe beginning in 1930. They didn't know she held the patent for spread-spectrum radio, a critical technology for secure communications. I learned of it in the 1960s after her work was declassified.

What other women of science did I learn of? Naturally, my mother had the books by Irene Joliot-Curie, so I knew of Madame Curie and her nearly-forgotten husband Pierre, and or Irene herself. Working only the memory banks here (Boy! Am I tempted to rely on Google…):

• Being a computer programmer for 40 years, it is a slam dunk that I'd know about Admiral Grace Hopper, a founder of the COBOL language, who is credited with changing our word for a machine error from "glitch" to "bug"…and pasted the wayward moth into her notebook.
• And of course, Ada Lovelace, who wrote the first computer program, for Charles Babbage's Analytical Engine, a machine that is a whole lot easier to emulate in software than to actually build of brass gears and ratchets.
• Being a DuPont-er, I knew of Stephanie Kwolek, inventor of Kevlar®. Wish I'd had the chance to meet her while she was still at the company.
• I have met Ellen Kullman, current CEO of DuPont, who began as a mechanical engineer.
• I read Silent Spring by Rachel Carson, and later a few of her essays.
• I read of "jumping genes" in a popular article by Barbara McClintock, and later the monographs in which she reported her work.
• Emmy Noether, honored by Alfred Einstein for cracking the math needed for his general theory of relativity.
• Florence Nightingale, who used statistics to show that battlefield hospitals were a hundred times as deadly as enemy bullets, and reformed nursing practice as a result.
• Lise Meitner, a physicist on a par with Bohr and Heisenberg.
• Rosalind Franklin, who would be the discoverer of the Double Helix if she hadn't been undercut by her boss.
• Lynn Margulis, who first explained how complex eukaryotic cells developed from collaborations among simpler prokaryotic cells (known today as bacteria).
• Sylvia Earle, in my opinion the most innovative practicing oceanographer.
• Sally Ride, the first American woman astronaut.
• Teacher Christa McAuliffe, who died aboard the Challenger when it blew up.
• Primatologist Jane Goodall, whose most recent book will be reviewed here in a few days.
• Primatologist Dian Fossey, who did for gorillas what Goodall did for chimps.

That's 16, and I could probably dig deeper, but time won't allow. With the help of good library work, Rachel Swaby has gathered biographical material for 52 of the best women scientists for her book Headstrong: 52 Women Who Changed Science—and the World. In her introduction she explains why she included only deceased women, so three people on my list above could not have appeared, though I wish she'd included Fossey. She also explains that the incredible fame of Marie Curie made it rather moot to include her, though she did include her daughter Irene.

Thus we learn of Alice Ball, who concocted the first practical, injectable serum of chaulmoogra oil to treat leprosy; Emilie de Chatelet (sorry I left off the accents), who translated Newton's Principia into French, and wrote a commentary about the same size; Annie Jump Cannon, who practically created the Henry Draper Catalog of Stellar Spectra by classifying nearly 400,000 stars, also pretty much creating the classification criteria as she went; and Marie Tharp, whose work resurrected the theory of continental drift that is now called Plate Tectonics. I guess I could add Tharp above as a 17^th; I read articles she wrote with Bruce Heezen in 1970.

It was enjoyable reading, but I think I'd have been more pleased were the book a third longer. Many of the mini-biographies are barely two pages, and the style would suit Joe Friday ("Just the facts, please."). It is a good beginning towards restoring a historical imbalance in science reporting. It wouldn't be a bad idea for a copy of this book to make its way into every middle school girl's backpack.

The specialness of islands

kw: book reviews, nonfiction, medicine, islands, cycads

Perception may not be reality, but it certainly feels that way. We go through life contentedly thinking other people are a lot like us. The growth from naivete to sophistication is largely involved in learning the ways we differ from others, and how to effectively cope with that. When we say someone "sees things differently", we usually mean understanding, not a different kind of physical vision. But among people who are not entirely blind, one man in twelve, and one woman in about 250, sees the world around as having different colors than those seen by most of us.

This illustration from 1895 is an attempt to show people with "normal" color vision the effects of a few kinds of color blindness. A truer depiction would have both flags II and III with brown stripes, just of differing contrast, and flags IV and V would be blurrier, because the blue-blind and total monochromats have much lower acuity of vision. Note that in flag IV the star field is black rather than blue.

I once studied color vision for 50 of my colleagues using printed color wheels, asking them to name the colors at certain angles, marked around the margin of the wheel. I tracked down a few folks who were color blind also, because the aim was to produce color maps for geologists that everyone could use with equal ease, and many geologists are color blind. As it happened, the results were somewhat confounded by the printing process, which used three colored inks. These are easier to distinguish from one another even by people with the usual, red-green, kinds of color blindness. Thus, we had  more flexibility using map colors than we'd originally expected.

What do we mean by red-green color blindness? It is actually of two varieties. The formal terms are protanopia and deuteranopia, based on the numbers 1 and 2. "1" refers to the red-sensitive cone cell (R cone), and "2" refers to the green-sensitive cone cell (G cone). However, the sensitivity curves of these two kinds of cells overlap quite a lot.

As seen in this diagram, the R cone and G cone have very similar sensitivity curves, just shifted from one another. It is somewhat surprising that the B cone has such a low sensitivity. In normal daylight, there is a lot of blue light, so it doesn't need a lot of sensitivity. In low light, such as the light of a full moon, for humans at least, the rod cells begin to work as the cones lose effectiveness. Rods are also blue-sensitive, though sort of between G cones and B cones. This is why moonlit scenes appear bluish. The most sensitive vision cells active under moonlight are blue-sensitive.

If either the R cones or G cones are missing or inactive, red, yellow and green shades can be distinguished from blues, but not from each other. The main difference is that the deepest reds appear totally dark to a protanope, while there is a blue-green region of the spectrum that is hard for a deuteranope to see. But because both conditions make the person unable to distinguish red from green, both are called red-green color blindness.

If none of the cones are present, or are not active, a person has only "night vision", with only the rods working. This is the primary type of achromatopsia, or total color blindness. The word is composed of "achromat", meaning "no color" and "opsia", referring to the eye. According to an old estimate, about one person in 30,000 has this condition, and it occurs in more men much more than women. Apparently, all kinds of color anomaly and color blindness are X-linked, so it is quite rare for a woman to have the same anomalous gene on both X chromosomes.

Because the "day vision" system isn't working, and rod cells typically bleach out entirely in bright light and stop working, achromatopes are day-blind or very sensitive to bright light, and cannot function in daylight without strong filters over their eyes. There are other unfortunate characteristics of the syndrome, such as nystagmus (rapid and unusual movement of the eyes), which may be side effects of the day-blindness.

Oliver Sacks, a polymath who almost incidentally is a neurologist, became fascinated upon learning of a pair of islands in the south Pacific, where more than 5% of the people are achromatopes. In the local language the condition is called maskun, meaning "not see", because of their day-blindness. They can function well enough in lower light, so they can do certain kinds of work. They are well accepted in their communities. Dr. Sacks and two others, one a scientist named Knut Nordby who is an achromatope, visited Pingelap and Pohnpei to study the phenomenon, and to bring dark glasses and other vision aids to people that have been coping without them. Their travels and work are described in a delightful way in Sacks's book The Island of the Colorblind, bound together with Cycad Island in the volume I read.

Both books explore the way island populations tend to concentrate certain characteristics. When you have a small population that has little or no contact with others, the statistics of gene-shuffling through the generations can exaggerate some conditions. In the case of Pingelap, a disastrous typhoon and following famine killed all but 20 people residing there, and fear of disease kept people from neighboring islands from visiting for more than a generation. One of those 20 carried the gene for achromatopsia, and inbreeding brought it into expression, as mentioned, to an incidence of about 5%. The numbers of those with maskun would be greater if it were not hard for them to find marriage partners.

The presence of Dr. Nordby was crucial to getting the people to talk willingly about their condition, and to help the research team gather useful genealogical data. The largest nearby island, Pohnpei, has a valley populated by immigrants from Pingelap, and a similar incidence of maskun. The team also went there to help those they could, and study the condition further.

Color blindness of this kind is trouble enough, but it doesn't kill you. A different medical condition is found on Guam, as Dr. Sacks tells us in Cycad Island. A slow, progressive disease called lytico-bodig in the local language has been endemic there for several generations. In the lytico form it resembles ALS, most famously afflicting Dr. Stephen Hawking, and earlier called Lou Gehrig's Disease, for that ballplayer died from it. The bodig form is more like Parkinson's Disease, leading to rigidity and paralysis, and is often accompanied by dementia. One sufferer cheerfully told Dr. Sacks, "Come back soon. I won't remember you, so I'll have the pleasure of getting to know you all over again."

Much of the latter book details a series of frustrated efforts over the years to determine what causes lytico-bodig. No final conclusion is offered, but the language strongly hints that the best hypothesis is poisoning of people who are genetically susceptible, in two different ways, to certain chemicals in the resin of cycads. The residents of Guam enjoy certain foods they prepare from cycad seed pods and other parts of the plant. They go to great lengths to detoxify them, because untreated, a small amount can kill. It seems to be like Japanese fugu, the puffer-fish, which an expert chef can prepare so it is safe to eat, if a bit "tingly", but several people are badly injured or killed each year from eating fugu. On Guam, cycad preparation is carried out with various levels of diligence. Also, a local fruit bat eats cycad fruits, and something that concentrates in its flesh can be damaging to the people, who enjoy bat meals.

It is stated that nobody born after 1952 suffers from lytico-bodig. This is probably because of changes in diet. Cycads are eaten much less now, and the fruit bat is seldom eaten because it is getting very scarce. Thus, a resident scientist named John Steele, who has studied the disease and befriended its sufferers for half his life, may find that the disease vanishes before he is able to prove its source. This is scientifically frustrating, but socially, it is a great relief.

Dr. Sacks's interests are wide-ranging, and I find he has five other books in print. Guess I'll track them down.

A well loved river in these parts

kw: book reviews, nonfiction, rivers, americana, culture, history, north american history

A friend thought it might be time that I learned more about the loveliest river in this area, so he gave me The Brandywine by Henry Seidel Canby, a book in the series "Rivers of America", edited primarily by Stephen Vincent Benét. The book was originally published in 1941; I read a paperback edition of 1969. The pen illustrations within are by Andrew Wyeth, and include sketch versions of paintings I've seen in the Brandywine River Museum and the Sanderson Museum. I live within a couple of miles of the Brandywine River, and I cross it via one bridge or another several times weekly. I also spend hours at a time along its banks in the gunpowder yards, so I guess it is high time!

Dr. Canby was born along the Brandywine in 1878, and though he spent many years as a professor at Yale, he returned to Wilmington frequently. We see through him this small, though significant river as it was between 75 and 130 years ago. Through both personal knowledge and wide reading he can trace the history and culture of the area as none other. In his childhood, though mills for making flour, textiles and gunpowder abounded, much of the Brandywine was still in a rather unspoiled state.

The forbidding geology had a lot to do with this; it was easier to build roads around the middle gorge than to try to cross it. If I recall correctly, Canby wrote that there were seven bridges crossing the river between Forks of the Brandywine in Pennsylvania and its confluence with the Christina River in Wilmington, a linear distance of about 14.5 miles, but more than 20 river miles. In that distance it descends more than 210 feet, a slope that averages roughly 10 feet per mile, but in the middle reaches it drops 33-34 feet per mile, making it one of the most favorable mill streams in the middle Atlantic region. It also means that what Canby calls "the gorge of the Brandywine" has some of the steepest terrain in northern Delaware and southern Chester County, Pennsylvania.

The author writes of the river as a lover of his beloved. He quotes other writers at some length, sometimes deploring their over-sentimentality, though he reflects it himself, just in the more restrained manner of a Yalie in all his dignity. It is a river worthy of much sentiment! During the days on which I volunteer in the yards at the Hagley Museum, situated in the steepest part of the gorge, I find the idle times are anything but onerous, being filled with visual delights backdropped by the rustle and grumble of the river.

It would not do justice to the book to simply catalog its 14 chapters. They are quite comprehensive. Rather, three items struck my fancy. Firstly, that the iconic "log cabin" was introduced by settlers along the Brandywine in the late 1600's, but did not spread beyond the area until nearly 1800. Elsewhere, and earlier here also, the vertical-log palisade was used where defense was needed, and various sorts of European structures otherwise, though they were usually quite unsuitable, particularly when badly constructed (the usual case). A log cabin is much easier for non-professionals to build into a sound and minimally drafty dwelling. Had Abraham Lincoln been born 5 or 10 years earlier, he would not have been born in a log cabin!

Secondly, there were no "Indian wars" along the river. Violent relations with native peoples were practically unknown here, and the great wars of legend took place many miles to the west and mainly after the Civil War. The Lenape and other "Delaware Indians" did find themselves exploited, but tended to complain through legal channels, and when they'd had enough most of them moved elsewhere of their own accord, primarily because of failure of the shad runs rather than violence. Nobody at the time understood clearly that all the mill dams were choking off the migration of the shad.

Thirdly, as already mentioned, in 1940 there were but 7 bridges along the lower Brandywine, and much of the river was comparatively unspoiled. Today fishermen are advised not to eat fish caught in the Brandywine anywhere south of the Forks, and by my count the bridges number 23: 17 road bridges, 3 foot bridges (one half collapsed) and 3 railroad trestles. There are also 9 mill dams still in existence, though only the 3 at Hagley are still in use to keep millraces filled. Compared to many mid-Atlantic rivers, though, the Brandywine still has significant unspoiled stretches. The existence of Brandywine Creek State Park protects one stretch of nearly 5 miles, and Hagley has kept another mile or so in a condition similar to that of 1921 when the mills closed.

I didn't yet  mention the Battle of the Brandywine, George Washington's failed attempt to keep the British from taking Philadelphia. Several good books about the battle had been published by 1940, so Canby gives a well-attested sketch of the engagements, but designedly leaves the details to others. The view from miles above: neither commander knew the area, nor had anyone with good local knowledge on staff; the farmers thereabouts were Quakers and were determined to help neither side of the conflict; scouts sent hither and yon brought conflicting reports; and the British were luckier in finding fords north of the Forks about which Washington was ignorant (as they also had been a day earlier), so they could flank the Colonials and get ahead of them. Thus, the British wintered in Philadelphia and the Colonial army in Valley Forge.

There is much, much more to the book, though it is less than 300 pages. To learn more of the river's geography, history of settlement, business growth, literature and art, and its role in American industrialization, you'll find this book a valuable and very entertaining resource.

The folly of evangelical anti-theism

kw: book reviews, nonfiction, polemics, science, religion, faith, pseudoscience

The human ape is a religious animal. It is part of our evolutionary heritage and we cannot escape it. Given that we must, by our nature, dedicate ourselves to something, what shall that something be?

To be religious does not require belief in God or a god or gods. Buddhism, for example, says nothing about the existence of any deity. Taoism at best only hints that some kind of god may be behind the scenes; that "Tao" might be personalized.

Mathematician Amir D. Aczel writes about a book a year, and his offering for 2014 is Why Science Does Not Disprove God. Several debates and discussions about science and religion in which he participated provided the initial fodder for writing the book. While he makes it clear he does not believe in the Lord God described by a literalist reading of the Bible, he is sympathetic to religion and even favorable.

The thesis of the book is simple: It is a misuse of science and scientific methods when the New Atheists use them to claim, not only that there is no God, but that there cannot be any kind of god. Who are the New Atheists? In order according to noise level, chiefly Richard Dawkins, Daniel Dennett, Lawrence M. Krauss, Christopher Hitchens (deceased), and Sam Harris. While atheism has long been with us, what is comparatively new is the evangelical tone of at least these five (although evangelical atheism is not particularly new, as an apparent conflict in the 1760's between Leonard Euler and Denis Diderot illustrates).

Even more to the point: The past couple of decades have been marred by increasingly shrill denouncements of Western and Judaeo-Christian institutions by extremist Islamic clerics. Over the same period, Dawkins and others have become equally shrill in their anti-religious campaign. The language of Dawkins in particular is just as inflammatory as any fatwa by a shrieking Imam. (BTW, this is me speaking; Dr. Aczel is too gentlemanly to point this out.)

Anti-theist claims are many and complex. The book tackles the most serious abuses of science by these "scientific" atheists in twelve chapters; three other chapters limn the history of the relationship of religion and science, and deal with more general matters. Along the way, Dr. Aczel shows how the New Atheists have grossly misused archaeology, cosmology, mathematics, probability, evolutionary theory, and the philosophy of science. Put it all together, and what do you have? A new religion based on pseudo-science, whose adherents are just as fervent, even rabid, as the most bigoted Bible-thumper (and, sad to say, there are all to many of those).

Scientists tend to overstate the power of science. The best scientists are humble and humbly grateful that science works as well as it does in so many realms. Unfortunately, they are a minority; most are simply "science workers", getting results and publishing as often as possible without giving much thought to the philosophy of science. Even more unfortunately, those "best" are outnumbered by those who arrogate divine powers to science, expecting all questions to be answered, if only we gather enough evidence, theorize deeply enough, and perhaps one day craft a "Theory of Everything."

Dr. Aczel demonstrates that such claims are overblown. He invokes the following:

• The Heisenberg Uncertainty Principle demonstrates that it is impossible to know with perfect accuracy both the position and the energy of a particle. Accuracy can be very, very good, but there are limits beyond which it will forever be impossible to measure. Even more, the Copenhagen Interpretation of Quantum Mechanics states that even in the absence of measurement, the precise path a particle will take has an irreducible amount of uncertainty. Diffraction in optical systems is evidence of this.
• Chaos Theory describes nonlinear systems (those in which the ongoing process influences itself) that are hypersensitive to initial conditions. In practical terms, when such systems are described mathematically, the equations cannot be solved in what we call "closed form". The simplest such system is the gravitational Three-Body Problem. Certain special cases have been mathematically solved, but it has been proven (in the mathematical sense) that the general case cannot be solved. Numerical (computer) simulations can be crafted over a limited span of time and space, but they are always dogged by the accumulation of rounding errors, until those dominate the result, and you are no longer simulating the system you began with. Even in "linear" systems (those with no feedback), successive iterations of a computer simulation still accumulate rounding errors, and special methods must be used if you need to test the magnitude of those accumulated errors. That greatly increases the computational cost of such simulations. And wouldn't you know it: Nature presents very few linear systems.
• The Schrödinger Wave Equation and other work by Edwin Schrödinger show that "things can go where you think they can't", and the poor cat of his paradox, being both dead and alive, actually illustrates our inability to know in detail the fate of any quantum event. By the way, I count the cat as an observer: it knows whether the cyanide got released, before the "official observer" opens the box to look.
• The Incompleteness Theorem of Kurt Gödel shows that it is possible to ask questions that cannot be answered using the mathematical (or "formal") system in which the question was asked. For example, formal logic is full of paradoxes that require one to step outside the system to elucidate. A famous example is the Barber of Seville: He shaves all men in Seville who do not shave themselves. Who shaves the Barber? Of course, the question has no answer in the system as set up. But if we bring the matter into the real world, we find that, of course, the Barber is bearded and is not shaved at all. The false premise of the paradox is that all men in Seville are clean-shaven.

The anti-Theists have formed a new church. You could call it a religion without any of the benefits. Of course, I agree that religious motivations have led to great abuses. For political reasons, couched as religion but really in a land grab, a Medieval Pope wrote a death warrant for the entire population of a province (or was it 3 provinces?) in France. Some 3 million persons were to be slaughtered. This was not carried out. Anti-Theists invoke the Crusades. Again, the motives were a mixture of religion and politics; for political gain the leaders incited religious fervor in ignorant knights and peasants. In fact, the terrible abuses of the history of Christianity in Europe and the Near East can just as well be invoked to prove that politics are evil…and they are!

But let us not forget the greatest slaughters of history. Do the names Adolf Hitler, Pol Pot, Joseph Stalin and Mao Zedong mean anything to you? Atheists one and all, responsible for the deaths of tens of millions or, in the case of Mao, more than 100 million. Compared to any of these four (and a couple of others), the Pope mentioned above was a piker, even had his order been carried out.

But we must remember that today's New Atheists claim the mantle science. Dr. Aczel has shown that at best they skew their science, and more frequently they abuse it all out of recognition. To put it baldly, the New Atheists, today's anti-Theists, are charlatans.

What does God think of this? The first six verses of Psalm 2 provide a clue:

¹ Why do the nations conspire
    and the peoples plot in vain?
² The kings of the earth rise up
    and the rulers band together
    against the Lord and against his anointed, saying,
³ “Let us break their chains
    and throw off their shackles.”

⁴ The One enthroned in heaven laughs;
    the Lord scoffs at them.
⁵ He rebukes them in his anger
    and terrifies them in his wrath, saying,
⁶ “I have installed my king
    on Zion, my holy mountain.”

First Contact - bugs versus gods?

kw: book reviews, science fiction, first contact, china, cultural revolution

What could induce someone to such deep hatred for humanity, as to wish our total destruction? A good place to begin might be the Chinese "Great Leap Forward", known in the West as the Cultural Revolution (hereafter, CR). This great leap backward set China back about a century, and it was only because of a massive shift in political attitudes—facilitated by Mao's untimely death in 1976—that the nation has been able to (nearly) grow into a 21^st Century superpower. Make no mistake, China's leaders are still committed Communists, but their social mind-control is only a whisker of what existed prior to the 1970's.

In The Three-Body Problem author Liu Cixin, using evocative and shocking prose, begins by setting the stage upon the background of the CR and a handful of persons so traumatized by it that they abandon hope that humanity can become upright and beneficent. One in particular, astrophysicist Ye Wenjie, determines a possible way to send a powerful signal to nearby stars using the Sun as an amplifier. When she gets a response more than 8 years later, a key element is in place. She devises a plan and eventually becomes titular leader of a group devoted to inviting the aliens to invade, and promising to collaborate with them in either reforming or destroying human society and perhaps the human race. As that sentence hints, there are factions within her organization, upon which much drama later in the book depends.

The star system thus contacted is commonly called Alpha Centauri, a 3-star system that is the "nearest star" to our solar system. Any planets of such a system are likely to have chaotic orbits, or at best alternating between stable and unstable orbits and thus climates. Thus the book's title. These aliens have strong motivation to move to a planet with a billions-of-years history of climatic stability, at least relative to theirs. They are called Trisolarians, for their three suns, and in late chapters are seen to have a considerable technological advantage over humans. I find that paradoxical; few of their hundreds of civilizations lasted longer than several generations, so how could they advance so far?

The book's translator, Ken Liu, writes in an afterword of the responsibility to provide not just a word-by-word translation (our different grammars don't really allow that anyway), but one that evokes emotions and illustrates concepts in such a way that the reader can partake of the author's thinking. (The author and translator are probably not closely related; Liu is the fourth most common Chinese surname.) For me, the writing is more straightforward than most modern English prose, which I found refreshing. It harked back to the fiction of my youth, when at least science fiction writers had fewer literary pretensions.

This is book one of a trilogy. All three have been translated, so I intend to track down the other two so I can see where the author is going, after closing with the foolishly arrogant message from the Trisolarians, "You're bugs!". However, their fleet will take four centuries to arrive. Can humanity achieve enough progress in that time to avert species-wide disaster? That is no settled matter, and curious Trisolarian AI's called Sophons may make it moot. I guess we must stay tuned.

For a Chinese writer to produce such a novel, in China, strongly indicates just how far that nation's leaders have moved from Maoist super-totalitarianism.

All your little bitty bits

kw: book reviews, nonfiction, science, atoms, popular treatments

I weigh a bit over 200 pounds, about 91 kg. Dry me out, and the residue would weigh about 85 lbs or 38+ kg. One could then (someone with a sufficiently strong stomach) divide up the dry mass into bone and muscle and so forth. But what is my atomic composition? If you also have that question, you'll find out in Your Atomic Self: The Invisible Elements That Connect You to Everything Else in the Universe by Curt Stager.

You can also get an answer of sorts from this table, but what fun is a table? In Your Atomic Self we find out, not just the amounts of the major chemical elements in us, but something about where they came from, how long they spend as a part of us, (not as long as you think!), and where they go when they leave us, or, ultimately, when each of "us" leaves our body behind.

For example, you and I are 2/3 oxygen, by weight. Most of that is in the water that makes up roughly 50-60% of our total weight (depending on bone/muscle/fat ratios). Where did all that oxygen come from? Surprisingly, the water we drink doesn't all become body water. Much of it is dissociated by various processes and some exits the body, rather soon, in our breath as carbon dioxide. The foods we eat all contain lots of oxygen, so some of that winds up in our body water, some in our tissues (fats and bone contain lots of oxygen), and some also gets breathed out as CO₂.

Though our lungs may have a capacity of half a gallon to a gallon (2-4 liters), we seldom breathe this deeply; less than one liter (1 quart) per breath is typical when we are at rest, which is nearly all the time for sedentary Westerners. About 20% of the air we breathe is oxygen, and all but 1% of the rest is nitrogen, which contributes to air pressure, but is not chemically active in this form—for which we ought to be very grateful! We use about 1/3 of the oxygen we breathe in and exhale the rest (which is why mouth-to-mouth resuscitation is effective). But at 20 breaths per minute, we allow nearly 30,000 liters of air in and out of our lungs daily, including about 5,800 liters of oxygen, of which about 2,000 liters enters our blood stream, and an equivalent amount, attached to carbon, exits as some 2,000 liters of CO₂.

Did you ever realize that a liter of CO₂ weighs 37.5% more than a liter of O₂? You'd lose a lot of weight if you did nothing but breathe all day! (Not really a lot; about a kilogram.) But as the author writes, there is more to the story than that, and it is not only the amount of water you take in and excrete.

Not all molecules of oxygen, and not all molecules of CO₂, are the same. Most oxygen is the isotope O-16, but a small amount (0.2%) is a heavier isotope, O-18 (there's a tiny amount of O-17 also). Then, most carbon is C-12, but ~1% is C-13 and about one atom of carbon in a trillion is C-14, a radioactive isotope produced mainly by cosmic rays. So while most O₂ molecules weigh 32 AMU (atomic mass units) and most CO₂ molecules weigh 44 AMU, the weight of stable O₂ can range up to 36, and that of stable CO₂ can range up to 49, while rare C-14·O₂ molecules can weigh between 46 and 50 AMU.

Why should that matter? The proportions of different molecular masses of these two substances can reveal the source of your diet and the air you've been breathing. Similar mass differences in water exist not only because of oxygen isotopes, but also hydrogen isotopes H-2 (deuterium) and H-3 (tritium). Physical processes such as evaporation tend to leave behind heavier molecules, and chemical processes, including photosynthesis in plants, prefer one isotope over another. This preference is not absolute, but it is enough that some kinds of foods have less O-18·O-16 in them compared to others, and so forth.

We also learn that each element connects us to the stars and to all life, each in its own way. Most hydrogen is primeval, created in the Big Bang, but some very small amount arises by spalling from processes such as cosmic ray collisions with atmospheric atoms. No elements heavier than lithium are primeval, but were created in extra-large stars that later exploded as supernovae, scattering them into the universe. So the hydrogen in you is billions of years older than your other elements…although a very few H atoms might be just a few days old! And all that oxygen and CO₂ that you've breathed out? Something or someone else (a great many "else's") are breathing it in, at least some of it, right now.

Each chapter of the book discusses primarily one element, or sometimes two. So, while we are sometimes told most life is composed of CHON (carbon, hydrogen, oxygen and nitrogen), the chapter on sodium and potassium reveals why your nerves wouldn't work without them, nor without calcium (the chapter after). Calcium isn't just about bones, and sodium isn't just about food tasting good. They are essential to second-by-second life processes. As it happens, one of the most essential is phosphorus. So much so, that this element may determine just how many humans Earth can support. It is really rather rare for an element that must make up 1% of your body's weight! That is more than ten times its abundance in the Earth's crust in general, but thousands of times as abundant as the 'available P' in the biosphere. Hmmm. I've predicted that coming wars will be over water. Perhaps later wars will be waged for access to phosphorus bearing minerals…if indeed those come later.

Though the book discusses 9 elements (I didn't mention iron above), that leaves a couple dozen "useful" elements in our makeup, so another book is not out of the question. I'd like that. I really enjoyed Your Atomic Self.