The Science Book

by Clifford A Pickover

  What do mountain lions, pumas, panthers, and catamonts have in common? These are but four of more than a dozen names given in the United States to the same animal, Felis concolor. When out and about in nature, we generally refer to plants and birds by their common names, but such names can be misleading. Crayfish, starfish, silverfish, and jellyfish are not related to each other and are not fish.

  Classification goes back to ancient times. Aristotle grouped animals based on their mode of reproduction, while Theophrastus classified plants by their uses and methods of cultivation. In his first edition of Systema Naturae (1735), the Swedish botanist and physician Carl Linnaeus introduced a new approach to taxonomy (the science of naming and classifying plants and animals). First, he assigned latinized names to plants and animals, based on a binomial nomenclature (genus and species) that uniquely designated each living organism—a system that is still used. For example, the genus Canis includes the closely related dogs, wolves, coyotes, and jackals, with each unique member assigned a species name. Moreover, Linnaeus developed a multi-level hierarchical classification in which higher “ranks” would incorporate successive groups at lower levels. Related genera would be grouped into families—Canis and Vulpes (foxes) are grouped together in Canidae. Based on the Linnaean classification, the most inclusive rank was the kingdom, of which he counted two: animal and plant.

  The Linnaean classification assigned organisms to different categories based on their physical characteristics and presumed natural relationships, and this was predicated on the then-prevailing Biblical interpretation that plants and animals were originally created in the form that they now exist. One century later, Darwin presented convincing evidence that two extant animals or plants might have had a common ancestor or that extinct organisms may have been the ancestors of those extant. Contemporary classifications are based on phylogenetic systematics, which incorporates relationships that include both extant and extinct organisms.

  SEE ALSO Fossil Record and Evolution (1836), Darwin’s Theory of Natural Section (1859), Domains of Life (1990).

  A signboard of Methodus plantarum sexualis (1736), a work by Georg Dionysius Ehret (1708–1770), a German botanist best known for his botanical illustrations. This image depicts the twenty-four classes of plant sexual systems devised by Linnaeus.

  1738

  Bernoulli’s Law of Fluid Dynamics • Clifford A. Pickover

  Daniel Bernoulli (1700–1782)

  Imagine water flowing steadily through a pipe that carries the liquid from the roof of a building to the grass below. The pressure of the liquid will change along the pipe. Mathematician and physicist Daniel Bernoulli discovered the law that relates pressure, flow speed, and height for a fluid flowing in a pipe. Today, we write Bernoulli’s Law as v2/2 + gz + p/ρ = C. Here, v is the fluid velocity, g the acceleration due to gravity, z the elevation (height) of a point in the fluid, p the pressure, ρ the fluid density, and C is a constant. Scientists prior to Bernoulli had understood that a moving body exchanges its kinetic energy for potential energy when the body gains height. Bernoulli realized that, in a similar way, changes in the kinetic energy of a moving fluid result in a change in pressure.

  The formula assumes a steady (non-turbulent) fluid flow in a closed pipe. The fluid must be incompressible. Because most liquid fluids are only slightly compressible, Bernoulli’s Law is often a useful approximation. Additionally, the fluid should not be viscous, which means that the fluid should not have internal friction. Although no real fluid meets all these criteria, Bernoulli’s relationship is generally very accurate for free flowing regions of fluids that are away from the walls of pipes or containers, and it is especially useful for gases and light liquids.

  Bernoulli’s Law often makes reference to a subset of the parameters in the above equation, namely that the decrease in pressure occurs simultaneously with an increase in velocity. The law is used when designing a venturi throat—a constricted region in the air passage of a carburetor that causes a reduction in pressure, which in turn causes fuel vapor to be drawn out of the carburetor bowl. The fluid increases speed in the smaller-diameter region, reducing its pressure and producing a partial vacuum via Bernoulli’s Law.

  Bernoulli’s formula has numerous practical applications in the fields of aerodynamics, where it is considered when studying flow over airfoils, such as wings, propeller blades, and rudders.

  SEE ALSO Archimedes Principle of Buoyancy (c. 250 BCE), Brownian Motion (1827), Wright Brothers’ Airplane (1903)

  Many engine carburetors have contained a venturi with a narrow throat region that speeds the air and reduces the pressure to draw fuel via Bernoulli’s Law. The venture throat is labeled 10 in this 1935 carburetor patent.

  1760

  Artificial Selection (Selective Breeding) • Michael C. Gerald with Gloria E. Gerald

  Abu Rayhan Biruni (973–1048), Robert Bakewell (1725–1795), Charles Darwin (1809–1882)

  A fundamental building block Charles Darwin used in conceptualizing his theory of natural selection was selective breeding, and he specifically cited the pioneering work of Robert Bakewell in this field. Darwin noted that many domesticated animals and plants were developed by intentionally breeding individuals with special prized traits.

  Selective breeding, a term coined by Darwin, was practiced by the Romans 2,000 years ago and was described by the Persian polymath Abu Rayhan Biruni during the eleventh century. However, it was Bakewell, a leading figure during the British Agricultural Revolution, who introduced it on a scientific basis. Bakewell was born into a family of English tenant farmers and spent his early years traveling on the Continent, learning farming methods. Upon his father’s death in 1760, he took control of the farm and transformed its grasslands for cattle grazing by using his innovative breeding techniques, irrigation, flooding, and fertilizing pasturelands. He then turned his attention to livestock and, through selective breeding, produced the New Leichester sheep lineage. Characterized as large and fine boned, this breed’s long lustrous wool was extensively exported to North America and Australia. Today, Bakewell’s legacy is not his breeds but his breeding methods.

  Desirable traits are specific to the species being bred, and individual members are crossbred to obtain a hybridized product with these characteristics. Plants are commonly bred for high crop yields, a fast growth rate, and resistance to disease and negative climatic conditions. For chickens, breeding objectives might include the quality and size of the eggs, the meat, and the production of young birds likely to successfully reproduce. Aquaculture, involving fish and shellfish, has yet to achieve its full potential. Breeding objectives include an increase in growth and survival rates, meat quality, and resistance to disease, and for shellfish, also shell size and color.

  SEE ALSO Wheat: The Staff of Life (c. 11,000 BCE), Agriculture (c. 10,000 BCE), Rice Cultivation (c. 7000 BCE) Darwin’s Theory of Natural Section (1859).

  A champion bull is being led in the ring at an agricultural show in Scotland, perhaps anticipating another blue ribbon to add to his collection.

  1761

  Bayes’ Theorem • Clifford A. Pickover

  Thomas Bayes (c. 1702–1761)

  Bayes’ theorem, formulated by British mathematician and Presbyterian minister Thomas Bayes, plays a fundamental role in science and can be stated by a simple mathematical formula used for calculating conditional probabilities. Conditional probability refers to the probability of some event A, given the occurrence of some other event B, written as P(A|B). Bayes’ theorem states: P(A|B) = [P(B|A) × P(A)]/P(B). Here, P(A) is called the prior probability of A because it is the probability of event A without taking into account anything we know about B. P(B|A) is the conditional probability of B given A. P(B) is the prior probability of B.

  Imagine we have two boxes. Box 1 has 10 golf balls and 30 billiard balls. Box 2 has 20 of each. You select a box at random and pull out a ball. We assume that the balls are equally likely to be selected. Your ball turns out to be a billiard ball
. How probable is it that you chose Box 1? In other words, what is the probability that you chose Box 1, given that you have a billiard ball in your hand?

  Event A corresponds to your picking Box 1. Event B is your picking a billiard ball. We want to compute P(A|B). P(A) is 0.5, or 50 percent. P(B) is the probability of picking a billiard ball regardless of any information on the boxes. It is computed as the sum of the probability of getting a billiard ball from a box multiplied by the probability of selecting a box. The probability of picking a billiard ball from Box 1 is 0.75. The probability of picking one from Box 2 is 0.5. The probability of getting a billiard ball overall is 0.75 × 0.5 + 0.5 × 0.5 = 0.625. P(B|A), or the probability of getting a billiard ball given that you selected Box 1, is 0.75. We can use Bayes’ formula to find that the probability of your having chosen Box 1, which is P(A|B) = 0.6.

  SEE ALSO Aristotle’s Organon (c. 350 BCE), Law of Large Numbers (1713), Laplace’s Théorie Analytique des Probabilités (1812).

  Box 1 (upper box) and Box 2 (lower box) are shown here. You select a box at random and withdraw a billiard ball. How probable it is that you choose the upper box?

  1761

  Causes of Cancer • Clifford A. Pickover

  Bernardino Ramazzini (1633–1714), John Hill (1707–1775), Sir Percivall Pott (1714–1788), Heinrich Wilhelm Gottfried von Waldeyer-Hartz (1836–1921), Katsusaburo Yamagiwa (1863–1930)

  Journalist John Bloom writes, “If the body’s cells represent a kind of Plato’s republic of somatic harmony—[the cells] each doing a specific job in precise proportion to every other cell—then cancer cells represent guerilla soldiers bent on a coup d’état.” Cancer refers to a group of diseases in which cells exhibit uncontrolled growth and sometimes metastasis (spreading to other areas of the body). Cancers are caused by abnormalities in the genetic material of cells and have many possible causes, including carcinogens (e.g., tobacco smoke, sunlight, or viruses) and random errors in DNA replication.

  Among the earliest documented cases of probable cancer are described in an Egyptian papyrus, c. 1600 BCE, involving eight cases of tumors in the breast. These tumors were treated by cauterization using a hot device called “the fire drill.”

  In 1713, Italian physician Bernardino Ramazzini reported on the virtual absence of cervical cancer in nuns when compared with married woman, speculating that sexual intercourse may increase cancer risk. The first paper describing a relationship between use of tobacco snuff and nasal cancer was published by English physician John Hill in 1761, after his startling discovery that his patients were all snuff users. He suggested, more generally, that substances in the environment may promote cancer. In 1775, another English physician, Percivall Pott, attributed high incidences of cancer of the scrotum among chimney sweeps to their contact with coal soot. He even recorded the cancer of a young boy who had been an apprentice to a chimney sweep. Finally, in 1915, Japanese researcher Katsusaburo Yamagiwa showed that frequent painting of rabbits’ skins with coal tar did indeed induce cancer.

  Note that in the 1860s, the German anatomist Wilhelm von Waldeyer-Hartz classified various kinds of cancer cells and suggested that cancer begins in a single cell and may spread through the blood or lymphatic system. Today, we know that tumor-suppressor genes, which normally inhibit uncontrolled cell division, may be inactivated by genetic changes associated with cancers.

  SEE ALSO Cell Division (1855), HeLa Cells (1951), Epigenetics (1983), Telomerase (1984).

  Two views of Clara Jacobi, a Dutch woman who had a tumor removed from her neck in 1689.

  1761

  Morgagni’s “Cries of Suffering Organs” • Clifford A. Pickover

  Andreas Vesalius (1514–1564), Gabriele Falloppio (1523–1562), Giovanni Battista Morgagni (1682–1771), Marie François Xavier Bichat (1771–1802), Rudolf Ludwig Karl Virchow (1821–1902)

  “The idea that symptoms of disease, from colds to cancer, arise from changes in organs and tissues of the body seems commonplace if not banal,” writes author John G. Simmons. “But the systematic correlation of the clinical history of disease with structural changes seen at autopsy was once a novel concept.” With the 1761 publication of Italian anatomist Giovanni Morgagni’s monumental work, De sedibus et causis morborum per anatomen indagatis (On the Seats and Causes of Disease), Morgagni became the father of modern anatomical pathology, the diagnosis of disease based on examination of bodies, organs, and tissues. For Morgagni, disease symptoms were the “cries of suffering organs.”

  Although other researchers such as Andreas Vesalius and Gabriele Falloppio had performed extensive anatomical studies, Morgagni’s work was notable in its accurate and systematic examinations of diseased organs and parts. De sedibus, published when Morgagni was 79 years old, records roughly 650 dissections. During clinical practice, Morgagni made careful observations of a patient’s illness and then attempted to identify the underlying causes upon autopsy. In conducting his research, he essentially debunked the ancient humoral theory of diseases, which posited an imbalance in bodily fluids as the root of disease. De sedibus identifies pathologies such as hepatic cirrhosis (a chronic degenerative disease in which normal liver cells are damaged and replaced by scar tissue), syphilitic lesions of the brain, stomach cancers and ulcers, and diseases of heart valves. Morgagni also observed that a lesion on one side of the brain, causing a stroke, led to paralysis of the other side of the body.

  So immersed was Morgagni in his work that in old age he remarked, “I have passed my life amidst books and cadavers.” Later, French anatomist Marie Bichat contributed to the field of pathology by identifying many kinds of body tissues and the effect of diseases on tissues. In the 1800s, the German pathologist Rudolf Virchow contributed to cellular pathology and was the first to recognize the effect of leukemia on blood cells.

  SEE ALSO De Humani Corporis Fabrica (1543), Cerebral Localization (1861), Brain Lateralization (1964).

  Frontispiece and title page of Giovanni Morgagni’s De sedibus.

  1783

  Black Holes • Clifford A. Pickover

  John Michell (1724–1793), Karl Schwarzschild (1873–1916), John Archibald Wheeler (1911–2008), Stephen William Hawking (1942–2018)

  Astronomers may not believe in Hell, but most believe in ravenous, black regions of space in front of which one would be advised to place a sign, “Abandon hope, all ye who enter here.” This was Italian poet Dante Alighieri’s warning when describing the entrance to the Inferno in his Divine Comedy, and, as astrophysicist Stephen Hawking has suggested, this would be the appropriate message for travelers approaching a black hole.

  These cosmological hells truly exist in the centers of many galaxies. Such galactic black holes are collapsed objects having millions or even billions of times the mass of our Sun crammed into a space no larger than our Solar System. According to classical black hole theory, the gravitational field around such objects is so great that nothing—not even light—can escape from their tenacious grip. Anyone who falls into a black hole will plunge into a tiny central region of extremely high density and extremely small volume . . . and the end of time. When quantum theory is considered, black holes are thought to emit a form of radiation called Hawking radiation (see “Notes and Further Reading”).

  Black holes can exist in many sizes. As some historical background, just a few weeks after Albert Einstein published his general relativity theory in 1915, German astronomer Karl Schwarzschild performed exact calculations of what is now called the Schwarzschild radius, or event horizon. This radius defines a sphere surrounding a body of a particular mass. In classical black-hole theory, within the sphere of a black hole, gravity is so strong that no light, matter, or signal can escape. For a mass equal to the mass of our Sun, the Schwarzschild radius is a few kilometers in length. A black hole with an event horizon the size of a walnut would have a mass equal to the mass of the Earth. The actual concept of an object so massive that light could not escape was first suggested in 1783 by the geologist John Michell. The te
rm “black hole” was coined in 1967 by theoretical physicist John Wheeler.

  SEE ALSO Sun-Centered Universe (1543), Telescope (1608), Main Sequence (1910), General Theory of Relativity (1915), Neutron Star (1933), Stellar Nucleosynthesis (1946), Gravitational Lensing (1979), Gravitational Waves (2016).

  LEFT: Black holes and Hawking radiation are the stimulus for numerous impressionistic pieces by Slovenian artist Teja Krašek. RIGHT: Artistic depiction of the warpage of space in the vicinity of a black hole.

  1785

  Coulomb’s Law of Electrostatics • Clifford A. Pickover

  Charles-Augustin Coulomb (1736–1806)

  “We call that fire of the black thunder-cloud electricity,” wrote essayist Thomas Carlyle in the 1800s, “but what is it? What made it?” Early steps to understand electric charge were taken by French physicist Charles-Augustin Coulomb, the preeminent physicist who contributed to the fields of electricity, magnetism, and mechanics. His Law of Electrostatics states that the force of attraction or repulsion between two electric charges is proportional to the product of the magnitude of the charges and inversely proportional to the square of their separation distance r. If the charges have the same sign, the force is repulsive. If the charges have opposite signs, the force is attractive.

  Today, experiments have demonstrated that Coulomb’s Law is valid over a remarkable range of separation distances, from as small as 10−16 meters (a tenth of the diameter of an atomic nucleus) to as large as 106 meters (where 1 meter is equal to 3.28 feet). Coulomb’s Law is accurate only when the charged particles are stationary because movement produces magnetic fields that alter the forces on the charges.