Electronic Newsletter for October, 2001.

Request for information:

Elmer [last name unknown]: Elmer was injured when his aircraft crashed on landing. He suffered head and neck injuries, which also resulted in memory loss. We're trying to reconstruct his time with the 486th, and determine if any other crewmates survived the crash.

Henry Rapp: His crew made an unscheduled stop in Belgium on 16 Nov 44.

Ernest Abril: Gunner on Munroe's crew 835th.

Grover Wimberly:  Air crew unknown. 834th

Frank A. McCreary: Pilot with the 833rd.

Anyone with information regarding the above individuals, or events are encouraged to contact me: webmaster486 at earthlink dot net

Books: The Mighty Eighth, by Roger Freeman is once again available, in paperback, at your bookstore.

Reunion: The reunion is approaching rapidly. Although the official deadline for registration has passed, Bob Bee will still accept registration letters. Walk-ins are also permitted. Dues for 2001 must be paid by registration time. For a copy of the registration letter, return to the Association webpage.

Robert Harper and I, with the assistance of Robin Douglas, will be interviewing veterans and their wives. A sample questionnaire is available on the Association website.

The Atomic Bomb (Part 1)

On August 6th, 1945, the Japanese city of Hiroshima was attacked by the Enola Gay, flying out of Tinian Island. She was escorted by two other B29s that day. Three days later, Boch's Car attacked Nagasaki. The Japanese finally capitulated on August 14th, accepting an unconditional surrender. The atomic bombs used against Japan were developed secretly under the Manhattan Project; however, it was no secret that the Americans were working on "the bomb." The fact is, throughout the 40's the British, Germans, Russian and the Japanese were working on nuclear weapons, the only question was, "Who would  win the race!"

The story of the Atomic Bomb (euphemistically called "nuclear devices" today) goes as far back as 500 BC. Greek philosophers pondered the question "How divisible is matter?" One school of thought, lead by Democritus, believed that Nature imposed a limit to how far matter could be split. The Greek word for indivisible, atomos, is the source of the word Atom. Unfortunately, other philosophers argued that any object, regardless how small, could, in principle, be split into two. The notion of an "atom" never took hold, and would not be revived again until 1805.

The alchemists of the middle ages practiced the art of concocting lotions, potions, poultices and other curatives for a variety of ailments. While more art than science, the alchemists amassed a wealth of knowledge regarding the manipulation of the elements. One of their more fabled goals was the transmutation of lead into gold. Lead, a gray, lusterless, soft metal seemed similar to Gold; a lustrous, yellow, soft metal. Their only apparent differences were luster and color. Alchemists were convinced that this transmutation could be achieved with the proper solutions added to lead. Their experiments were doomed to failure; the secret of transmutation beyond their reach.

The art of alchemy matured into the science of chemistry. By the late 18th century chemists had come to understand a great deal about the elements, and compounds derived from those elements. Chemists knew that for any compound the ratio of its constituent elements was a constant. Regardless of where the compound was created, or found in nature, the ratios of elements never varied. For example, 2 grams of hydrogen, and 16 grams of oxygen always created 18 grams of water (to the level of accuracy they could measure). By 1805 enough information was available to lead John Dalton, a Quaker, to postulate the existence of atoms and molecules. Molecules being made from atoms of various elements. By analyzing weights Dalton was able to make measurements of the individual atomic masses, but little more could be discovered about the structure of atoms.

In 1867, a Scottish physicist, James Clerk Maxwell, published his theory unifying electricity and magnetism. From this theory physicists now saw light as a wave composed of oscillating electric and magnetic fields. The theory also predicted the speed of light from physical constants. Although, it had been known since the time of Isaac Newton that light could be thought of as a wave phenomenon, there was no theoretical way to describe light until Maxwell's theory appeared. The unification of Electric and magnetic field theories signaled the beginning of the "Modern Physics" era, and would lead to more advances that would have profound consequences on humanity.

During the years following the publishing of Maxwell's theory, physicists began to investigate electromagnetic phenomena. These experiments took many forms, some of which included tubes penetrated by electrodes. These tubes, called cathode ray tubes, might have contained a vacuum, or a pure gas. When strong potential differences (voltages) were applied to the electrodes electric current would be generated. In the presence of a gas, the current would create a glow, the color of which was characteristic of the gas present. In a vacuum, the current passed invisibly between electrodes. In 1895 a variation of these experiments conducted by Wilhelm Konrad Röntgen gave some unexpected results.

In this particular experiment, the electrodes were not aligned with the axis of the tube, but at a 90 angle. When a strong voltage was applied, the current would leave the face of one electrode, make a bend of 90 and enter the other electrode. When this was done, Röntgen noticed that the glass opposite the gap in the electrode fluoresced. He also noted that the fluorescence was visible on neighboring glass tubes. He placed a sheet of paper between the tubes to see if the paper would block the fluorescing rays like it would ordinary light. To his surprise, the paper had no effect. He next used his hand to block the rays, and to his amazement, the shadows of rings and bones within his hand were cast upon the glass. Not knowing what these penetrating rays were he named them "X-Rays." (also known as roentgen rays). He wrote a report and published articles about his discovery. Photos were distributed showing the first images of the inside of human hand. Physicians immediately realized the importance of this discovery and a new medical discipline was born. The matter of these X-rays and their association with fluorescence inspired others to do new experiments involving other sources of fluorescence.

[A side note: In 1871, Jules Verne, a French novelist, published his book, "Twenty Thousand Leagues Under the Sea." Most everyone knows of this work. The ship, a submarine, captained by a man named Nemo, was powered by the atom. This prophetic book was written before anyone knew that atoms would be a source of power, and would inspire a generation of physicists.]

A French Chemist named Henri Becquerel was interested in the connection of these newly discovered X-rays and fluorescence. Becquerel was familiar with substances which naturally fluoresced and wondered if these X-rays were naturally associated with this fluorescence too. To test this hypothesis he took small pieces of Uranium Sulfide (US2) and sprinkled them over a heavy envelope containing a photographic plate. When exposed to ultraviolet light (UV), US2 would fluoresce. He then placed the plate in the Sun, to induce the fluorescence in the US2. After a time, he developed the plate, and saw that penetrating rays accompanied the fluorescing rays of US2. During one set of experiments, the Sky was overcast, and Becquerel placed the photographic plate with the US2 in a drawer. Four days later, he developed the plates, and discovered the US2 had exposed them even without Sun. This lead him to believe that US2 emitted a type of radiation similar to X-rays. Other chemists joined the search for other naturally radioactive substances. Among the more prolific were Pierre and Marie Curie.

This search yielded a number of radioactive substances, and revealed the presence of 3 types of radiation. These were called Alpha, Beta and Gamma. Alpha radiation turned out to be the nucleus of a helium atom. Matter emitting alpha particles was transformed into an element with an atomic number reduced by 2 units, and an atomic weight reduced by 4 units. Beta emitters would either increase, or decrease, their atomic number by 1 with no apparent change in atomic weight. Gamma radiation was very penetrating like X-rays, and often accompanied alpha or beta decay.

Physicists now had to consider the validity of the notion of atoms. J. J. Thomson postulated what became known as the "plum pudding" model of the atom. He envisioned a minute particle of matter, positively charged, and studded with electrons. The atomic number of an atom identified its species, and the number of positive electrical charge units. The amount of positive charge in the atom, determined the number of electrons embedded in it, to neutralize the positive charge. The validity of this model was put to the test by an experimental physicist named Ernest Rutherford; a New Zealander working at Cambridge in England. He tasked two graduate students to set up an experiment in which a very thin sheet of gold leaf was bombarded by alpha particles. The results of this experiment showed that the alpha particles would penetrate the gold leaf. Some would go straight through, while others were scattered at large angles. Rutherford made some theoretical calculations for the scattering phenomenon assuming that the atom of the plum pudding model where permeable. The results did not match the observations. He then assumed that the atom was actually composed mostly of a vacuum, with a positively charged nucleus orbited by electrons. The new calculations gave results that matched the observation well. Rutherford now theorized that an atom looked like a mini-solar system. A positively charged nucleus, occupying a small volume of space within the atom, and orbited by a number of electrons. This discovery would win Rutherford a Nobel prize in physics. His model of the atom, however, created some serious questions. Primarily, the electrons in orbit about the nucleus are accelerating, and, according to electromagnetic theory should be emitting electromagnetic radiation. The source of energy being the orbital energy of the electrons. Consequently, the electrons should spiral into the nucleus as they lost energy. If this did not happen, then why not?

The answer came from Niels Bohr, a Danish physicist. Bohr called upon a theory of radiation proposed by a German physicist, Maxwell Planck. Planck analyzed the radiation from incandescent bodies, and concluded that the light they emit is done so in bursts that he named quanta, and later referred to as photons. These quanta of electromagnetic radiation had a specific frequency, and a specific energy. Bohr stated that the Rutherford atom was indeed stable, but that electrons could change orbits only if they absorbed, or emitted, a quantum of energy equivalent to the change in orbital energy. Thus, the Rutherford atomic model was stable. The picture of the innards of the atom were finally emerging, but many questions remained.

An atom of hydrogen had a nucleus with a single unit of electric charge, and having an atomic number of one. A single electron orbited a neutral atom of hydrogen. The atomic weight was very close to one. A Helium nucleus had twice the charge of hydrogen, but an atomic weight almost 4 times heavier. For the lighter elements, excluding hydrogen, the ratio of electric charge to atomic mass was almost 1/2. As the atomic number increased, this fraction decreased. This caused physicists to stop and think about what was going on. The nucleus of the Hydrogen atom was a particle called a proton, and that the positive charge of any nucleus was carried by multiple protons. If this was the case, then why did the mass of a nucleus increase faster than its charge? Moreover, why didn't the electrostatic repulsion of the like charges in the nucleus cause it to disintegrate? Rutherford postulated the existence of a third elementary particle, that was neutrally charged and helped bind the protons together within the nucleus. He tasked yet another Student, James Chadwick, to search for evidence of this particle's existence.

As Chadwick began his research, he came across an article written by the Curies discussing the results of a recent experiment. Chadwick immediately knew that the Curies had stumbled across the very particle that he was to look for. Building on the experiments conducted by the Curies, Chadwick was able to find positive proof that the neutron did exist in 1932. For his work Chadwick won the Nobel prize. The existence of the neutron made the picture of the atom complete. It also lead to the discovery of "isotopes." An isotope is an atom having a given atomic number, but different numbers of neutrons. Hydrogen has no neutrons in its nucleus, but Hydrogen has two other isotopes that do. Deuterium is an atom of Hydrogen possessing one neutron, and Tritium is a Hydrogen atom possessing 2 neutrons. This explains why the average weight of naturally occurring Hydrogen is heavier than a single atom of simple Hydrogen.

Later, Frederic Joliot and his wife Irene Curie (daughter of Pierre and Marie), were conducting experiments by bombarding nuclei with alpha particles. Working with a newly discovered species of atom, Polonium (named for Marie's native land Poland), they discovered that radioactivity could be induced.

The alpha particle provided physicists with a unique tool for probing the atom's nucleus, and inducing radioactivity. The electrostatic repulsion between the two particles made it difficult to probe heavier nuclei without accelerating alpha particles to high energies. A new device, called the cyclotron solved this problem. However, Rutherford suggested that the neutron, with no charge, could be used in place of the alpha particle without a need to accelerate it. Physicists and chemists began a systematic study of nuclei by bombarding them with neutrons. An Italian physicist, Enrico Fermi, reported when he bombarded Uranium he produced man made elements heavier than Uranium (called trans-uranics), but his chemists could not confirm that; all they could find were hints that the resultant nuclei were much lighter.

Next month: Fission and the Manhattan Project.

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