The Science Book

by Clifford A Pickover

  Molds are not the only producers of natural antibiotics. For example, the bacterium Streptomyces was the source of streptomycin and the tetracyclines. Penicillin and these later-discovered antibiotics triggered a revolution in the battle against disease.

  SEE ALSO Germ Theory of Disease (1862), Antiseptics (1865), Chlorination of Water (1910).

  Close-up image of the Penicillium fungus, which produces penicillin.

  1929

  Hubble’s Law of Cosmic Expansion • Clifford A. Pickover

  Edwin Powell Hubble (1889–1953)

  “Arguably the most important cosmological discovery ever made,” writes cosmologist John P. Huchra, “is that our Universe is expanding. It stands, along with the Copernican Principle—that there is no preferred place in the Universe, and Olbers’ Paradox—that the sky is dark at night, as one of the cornerstones of modern cosmology. It forced cosmologists to [consider] dynamic models of the Universe, and also implies the existence of a timescale or age for the Universe. It was made possible . . . primarily by Edwin Hubble’s estimates of distances to nearby galaxies.”

  In 1929, American astronomer Edwin Hubble discovered that the greater the distance a galaxy is from an observer on the Earth, the faster it recedes. The distances between galaxies, or galactic clusters, are continuously increasing and, therefore, the Universe is expanding.

  For many galaxies, the velocity (e.g. the movement of a galaxy away from an observer on the Earth) can be estimated from the red shift of a galaxy, which is an observed increase in the wavelength of electromagnetic radiation received by a detector on the Earth compared to that emitted by the source. Such red shifts occur because galaxies are moving away from our own galaxy at high speeds due to the expansion of space itself. The change in the wavelength of light that results from the relative motion of the light source and the receiver is an example of the Doppler Effect. Other methods also exist for determining the velocity for faraway galaxies. (Objects that are dominated by local gravitational interactions, like stars within a single galaxy, do not exhibit this apparent movement away from one another.)

  Although an observer on the Earth finds that all distant galactic clusters are flying away from the Earth, our location in space is not special. An observer in another galaxy would also see the galactic clusters flying away from the observer’s position because all of space is expanding. This is one of the main lines of evidence for the Big Bang from which the early Universe evolved and the subsequent expansion of space.

  SEE ALSO Cosmic Microwave Background (1965), Cosmic Inflation (1980), Dark Energy (1998).

  For millennia, humans have looked to the skies and wondered about their place in the cosmos. Pictured here are Polish astronomer Johannes Hevelius and his wife Elisabeth making observations (1673). Elisabeth is considered to be among the first female astronomers.

  1931

  Gödel’s Theorem • Clifford A. Pickover

  Kurt Gödel (1906–1978)

  Austrian mathematician Kurt Gödel was an eminent mathematician and among the most brilliant logicians of the twentieth century. The implications of his incompleteness theorem are vast, applying not only to mathematics but also touching on areas such as computer science, economics, and physics. When Gödel was at Princeton University, one of his closest friends was Albert Einstein.

  Gödel’s theorem, published in 1931, had quite a sobering effect upon logicians and philosophers because it implies that within any rigidly logical mathematical system, propositions or questions exist that cannot be proved or disproved on the basis of axioms within that system, and therefore it is possible for basic axioms of arithmetic to give rise to contradictions. This makes mathematics essentially “incomplete.” The repercussions of this fact continue to be felt and debated. Moreover, Gödel’s theorem put an end to centuries of attempting to establish axioms that would provide a rigorous basis for all of mathematics.

  Author Hao Wang writes on this very subject in his book Reflections on Kurt Gödel: “The impact of Gödel’s scientific ideas and philosophical speculations has been increasing, and the value of their potential implications may continue to increase. It may take hundreds of years for the appearance of more definite confirmations or refutations of some of his larger conjectures.” Douglas Hofstadter notes that a second theorem of Gödel’s also suggests the inherent limitation of mathematical systems and “implies that the only versions of formal number theory which assert their own consistency are inconsistent.”

  In 1970, Gödel’s mathematical proof of the existence of God began to circulate among his colleagues. The proof was less than a page long and caused quite a stir. Toward the end of his life, Gödel was paranoid and felt that people were trying to poison him. He stopped eating and died in 1978. During his life, he had also suffered from nervous breakdowns and hypochondria.

  SEE ALSO Aristotle’s Organon (c. 350 BCE), Euclid’s Elements (c. 300 BCE), Cantor’s Transfinite Numbers (1874).

  Albert Einstein and Kurt Gödel. Photo by Oskar Morgenstern, Institute of Advanced Study Archives, Princeton, 1950s.

  1932

  Antimatter • Clifford A. Pickover

  Paul Dirac (1902–1984), Carl David Anderson (1905–1991)

  “Fictional spaceships are often powered by ‘antimatter drives’,” writes author Joanne Baker, “yet antimatter itself is real and has even been made artificially on the Earth. A ‘mirror image’ form of matter . . ., antimatter cannot coexist with matter for long—both annihilate in a flash of energy if they come into contact. The very existence of antimatter points at deep symmetries in particle physics.”

  The British physicist Paul Dirac once remarked that the abstract mathematics we study now gives us a glimpse of physics in the future. In fact, his equations from 1928 that dealt with electron motion predicted the existence of antimatter, which was subsequently discovered. According to the formulas, an electron must have an antiparticle with the same mass but a positive electrical charge. In 1932, U.S. physicist Carl Anderson observed this new particle experimentally and named it the positron. In 1955, the antiproton was produced at the Berkeley Bevatron (a particle accelerator). In 1995, physicists created the first anti-hydrogen atom at the CERN research facility in Europe. CERN (Organisation Européenne pour la Recherche Nucléaire), or the European Organization for Nuclear Research, is the largest particle physics laboratory in the world.

  Antimatter-matter reactions have practical applications today in the form of positron emission tomography (PET). This medical imaging technique involves the detection of gamma rays (high-energy radiation) emitted by a positron-emitting tracer radionuclide, an atom with an unstable nucleus.

  Modern physicists continue to offer hypotheses to explain why the observable universe appears to be nearly entirely composed of matter and not antimatter. Could regions of the universe exist in which antimatter predominates?

  Upon casual inspection, antimatter would be almost indistinguishable from ordinary matter. Physicist Michio Kaku writes, “You can form antiatoms out of antielectrons and antiprotons. Even antipeople and antiplanets are theoretically possible. [However], antimatter will annihilate into a burst of energy upon contact with ordinary matter. Anyone holding a piece of antimatter in their hands would immediately explode with the force of thousands of hydrogen bombs.”

  SEE ALSO Electron (1897), Dirac Equation (1928), Little Boy Atomic Bomb (1945).

  In the 1960s, researchers at Brookhaven National Laboratory used detectors, such as this, for studying small brain tumors that absorbed injected radioactive material. Breakthroughs led to more practical devices for imaging areas of the brain, such as today’s PET machines.

  1932

  Neutron • Clifford A. Pickover

  Sir James Chadwick (1891–1974), Irène Joliot-Curie (1897–1956), Jean Frédéric Joliot-Curie (1900–1958)

  “James Chadwick’s road to the discovery of the neutron was long and tortuous,” writes chemist William H. Cropper. “Because they carried no electrical c
harge, neutrons did not leave observable trails of ions as they passed through matter, and left no tracks in Wilson’s cloud chamber; to the experimenter, they were invisible.” Physicist Mark Oliphant writes, “The neutron was discovered as a result of a persistent search by Chadwick, and not by accident as were radioactivity and X-rays. Chadwick felt intuitively that it must exist and never gave up the chase.”

  The neutron is a subatomic particle that is part of every atomic nucleus except for ordinary hydrogen. It has no net electric charge and a mass slightly greater than that of a proton. Like the proton, it is composed of three quarks. When the neutron is inside the nucleus, the neutron is stable; however, free neutrons undergo beta decay, a type of radioactive decay, and have a mean lifetime of approximately 15 minutes. Free neutrons are produced during nuclear fission and fusion reactions.

  In 1931, Irène Joliot-Curie (daughter of Marie Curie, the first person honored with two Nobel Prizes) and her husband Frédéric Joliot described a mysterious radiation produced by bombarding beryllium atoms with alpha particles (helium nuclei), and this radiation caused protons to be knocked loose from hydrogen-containing paraffin. In 1932, James Chadwick conducted additional experiments and suggested that this new kind of radiation was composed of uncharged particles of approximately the mass of the proton, namely, neutrons. Because the free neutrons are uncharged, they are not hindered by electrical fields and penetrate deeply into matter.

  Later, researchers discovered that various elements, when bombarded by neutrons, undergo fission—a nuclear reaction that occurs when the nucleus of a heavy element splits into two nearly equal smaller pieces. In 1942, researchers in the U.S. showed that these free neutrons produced during fission can create a chain reaction and enormous amounts of energy, and could be used to create an atomic bomb—and nuclear power plants.

  SEE ALSO Radioactivity (1896), Atomic Nucleus (1911), Neutron Star (1933), Energy from the Nucleus (1942), Standard Model (1961), Quark (1964).

  The Brookhaven Graphite Research Reactor—the first peacetime reactor to be constructed in the United States following World War II. One purpose of the reactor was to produce neutrons via uranium fission for scientific experimentation.

  1933

  Dark Matter • Clifford A. Pickover

  Fritz Zwicky (1898–1974), Vera Cooper Rubin (1928–2016)

  Astronomer Ken Freeman and science-educator Geoff McNamara write, “Although science teachers often tell their students that the periodic table of the elements shows what the Universe is made of, this is not true. We now know that most of the Universe—about 96% of it—is made of dark material [dark matter and dark energy] that defies brief description. . . .” Whatever the composition of dark matter is, it does not emit or reflect sufficient light or other forms of electromagnetic radiation to be observed directly. Scientists infer its existence from its gravitational effects on visible matter such as the rotational speeds of galaxies.

  Most of the dark matter probably does not consist of the standard elementary particles—such as protons, neutrons, electrons and known neutrinos—but rather hypothetical constituents with exotic-sounding names such as sterile neutrinos, axions, and WIMPs (Weakly Interacting Massive Particles, including neutralinos), which do not interact with electromagnetism and thus cannot be easily detected. The hypothetical neutralinos are similar to neutrinos, but heavier and slower. Theorists also consider the wild possibility that dark matter includes gravitons, hypothetical particles that transmit gravity, leaking into our universe from neighboring universes. If our universe is on a membrane “floating” within a higher dimensional space, dark matter may be explained by ordinary stars and galaxies on nearby membrane sheets.

  In 1933, the astronomer Fritz Zwicky provided evidence for the existence of dark matter through his studies of the motions of the edges of galaxies, which suggested a significant amount of galactic mass was undetectable. In the late 1960s, astronomer Vera Rubin showed that most stars in spiral galaxies orbit at approximately the same speed, which implied the existence of dark matter beyond the locations of stars in the galaxies. In 2005, astronomers from Cardiff University believed they had discovered a galaxy in the Virgo Cluster made almost entirely of dark matter.

  Freeman and McNamara write, “Dark matter provides a further reminder that we humans are not essential to the Universe. . . . We are not even made of the same stuff as most of the universe. . . . Our Universe is made of darkness.”

  SEE ALSO Newton’s Laws of Motion and Gravitation (1687), Black Holes (1783), Dark Energy (1998).

  One early piece of evidence for the existence of dark matter is the 1959 observation of astronomer Louise Volders who demonstrated that spiral galaxy M33 (pictured here in a NASA Swift Satellite ultraviolet image) does not spin as expected according to standard Newtonian dynamics.

  1933

  Polyethylene • Derek B. Lowe

  Reginald Oswald Gibson (1902–1983), Michael Wilcox Perrin (1905–1988), Eric Fawcett (1927–2000)

  The year 1933 marks the first industrial synthesis of polyethylene, but (unfortunately) not the first reliable one. It had originally been prepared in 1898 in an accident during German chemist Hans von Pechmann’s work with pure diazomethane. No one was foolhardy enough to work with the explosive and toxic diazomethane on a larger scale, so this remained a chemical footnote until British chemist Reginald Oswald Gibson and British-Canadian physicist Eric Fawcett tried a high-pressure, high-temperature reaction between ethylene gas and benzaldehyde (the same compound that inspired the work of German chemists Friedrich Wöhler and Justus von Liebig on functional groups back in 1832). The white, waxy polymer they produced turned out to be all long chains of CH2 (methylene) groups from the polymerized ethylene, and, with its resistance to chemicals and solvents and its malleability, it seemed as if it could be a very useful material.

  Getting the reaction to work reproducibly, however, was very frustrating until British chemist Michael Wilcox Perrin figured out the right conditions in 1937. Traces of oxygen, as it happened, caused that first reaction’s accidental success, and later routes used small amounts of more reliable free radical initiators under milder conditions. Polyethylene became a secret material of World War II when its use as an insulator in electronics (such as radar equipment) was discovered. By the end of the war, it was being made on a large scale, and its many forms (hard blocks, thin sheets, flexible panels) were beginning to be appreciated.

  Today polyethylene is the most common plastic polymer in the world. Depending on how it’s made (how long the chains are, whether any branching compounds are added to the mix, and so on), it can take on a huge variety of properties, from flexible (low-density polyethylene, or LDPE) to rigid (high-density polyethylene, or HDPE). Hundreds of millions of tons are made each year, and it’s found in products as varied as squeeze bottles, trash bags, sporting goods, and toys. Research on it is still continuing—all in all, an impressive performance for something whose first preparations were all mistakes.

  SEE ALSO Rubber (1839), Plastic (1856), Doped Silicon (1941).

  Versatile polyethylene is incorporated into countless products and materials, including puncture-resistant fencing gear.

  1933

  Neutron Stars • Clifford A. Pickover

  Fritz Zwicky (1898–1974), Jocelyn Bell Burnell (b. 1943), Wilhelm Heinrich Walter Baade (1893–1960)

  Stars are born when a large amount of hydrogen gas starts to collapse in on itself due to gravitational attraction. As the star coalesces, it heats up, produces light, and helium is formed. Eventually the star runs out of hydrogen fuel, starts to cool, and enters one of several possible “graveyard states” such as a black hole or one of its crushed cousins such as a white dwarf (for relatively small stars) or a neutron star.

  More particularly, after a massive star has finished burning its nuclear fuel, the central region collapses due to gravity, and the star undergoes a supernova explosion, blowing off its outer layers. A neutron star, made almost entirely of
uncharged subatomic particles called neutrons, may be created by this gravitational collapse. A neutron star is prevented from achieving the complete gravitational collapse of a black hole due to the Pauli Exclusion Principle repulsion between neutrons. A typical neutron star has a mass between about 1.4 and 2 times the mass of our Sun, but with a radius of only around 7.5 miles (12 kilometers). Interestingly, neutron stars are formed of an extraordinary material, known as neutronium, which is so dense that a sugar cube could contain the crushed mass of the entire human population.

  Pulsars are rapidly rotating, highly magnetic neutron stars that send out steady electromagnetic radiation that arrives at the Earth as pulses due to the star’s rotation. The pulses are at intervals ranging from milliseconds to several seconds. The fastest millisecond pulsars spin over 700 times per second! Pulsars were discovered in 1967 by graduate student Jocelyn Bell Burnell in the form of radio sources that seemed to blink at a constant frequency. In 1933, astrophysicists Fritz Zwicky and Walter Baade proposed the existence of a neutron star, only a year after the discovery of the neutron.

  In the novel Dragon’s Egg, creatures live on a neutron star, where the gravity is so strong that mountain ranges are about a centimeter high.

  SEE ALSO Black Holes (1783), Main Sequence (1910), Pauli Exclusion Principle (1925), Neutron (1932).

  In 2004, a neutron star underwent a “star quake,” causing it to flare brightly, temporarily blinding all X-ray satellites. The blast was created by the star’s twisting magnetic fields that can buckle the surface of the neutron star. (Artist’s concept from NASA.)