This image compilation is based on the “Modern” birthstone chart of the International Gem Society. On the top row, from left to right, are the birthstones for January (Garnet), February (Amethyst), March (Aquamarine), and April (Diamond). Middle row: May (Emerald), June (Alexandrite), July (Ruby), and August (Peridot). Bottom row: September (Sapphire), October (Tourmaline), November (Citrine), December (Blue Topaz). All images from Wikimedia Commons.
Birthstones!
If you have disposable income and like shiny objects, you’ve probably heard about birthstones. Birthstones are a collection of gemstones with one or more stones matched to the month of your birth. There is no standard set of birthstones, with separate groupings being created by gemology organizations in the United States, Britain, and Japan. Some months have more than one birthstone, and stones have been added or removed from lists as recently as 2016.
Given how fluid the concept of a birthstone seems to be, I’ve decided to throw my hat in the ring for this Photos of the Month post and create my own compilation of gemstones. And of course – they have to be based on real events in the history of science!
You may be tempted to comment, “But these aren’t gemstones! Some of them aren’t even minerals.” If so, just remember that:
Portrait of Bell Labs scientist Mathias Alten Gilleo. Credit: AIP Emilio Segrè Visual Archives, Physics Today Collection. Gilleo Mathias A1.
The first “science” birthstone is the only one which is the same as the regular version … sort of. The regular birthstone for January is garnet, but the “science” birthstone is a YIG, or Yttrium Iron Garnet. A YIG is a synthetic rare-earth-iron garnet with interesting properties for acoustic and magneto-optical applications.
F. Bertaut and F. Forrat were the first to discover that YIGs are ferrimagnetic, meaning that it has groups of atoms with magnetic moments pointing in opposite directions. They published their findings in the January 1956 issue of the Proceedings of the French Academy of Sciences.
Bertaut and Forrat narrowly beat out two scientists from Bell Labs – S. Geller and M. Gilleo. Geller and Gilleo reported on their studies of YIGs at the June 1956 meeting of the American Crystallographic Association. They took care to note in a publication a few months later that “Ferrimagnetism in rare-earth-iron garnets was discovered independently by the authors, though at a later date and in a way different from that of Bertaut & Forrat (1956).”
Bell Labs was naturally extremely interested in the acoustic properties of YIGs, as shown in this picture of Eugene Gordon and Conway LeCraw.
Eugene I. Gordon (left), and Conway LeCraw discuss properties of yttrium iron garnet (YIG), using a model of the unit cell of a YIG crystal. LeCraw is holding a YIG sphere used in measurements of the material's acoustic properties at Bell Telephone Laboratories. Circa 1962. Credit: Bell Laboratories / Alcatel-Lucent USA Inc., courtesy AIP Emilio Segrè Visual Archives, Hecht Collection. Gordon Eugene F3.
Chien-Shiung Wu sitting at equipment. Credit: AIP Emilio Segrè Visual Archives, Physics Today Collection. Wu Chien-Shiung F4.
As the previous month illustrated, there is rarely a single date of discovery; experiments often take place over multiple months and the same discovery may be made independently by multiple researchers. For this reason I have often assigned birthstones to the months in which the big breakthroughs associated with them were published. This is again the case for Cobalt and the month of February.
Much has been written about Chien Shiung Wu’s experiment which confirmed that parity is not confirmed in beta decay, but did you know that she used the radioactive decay of Cobalt-60? Wu had gathered enough data by December 1956, but her results were published in February 1957 alongside a set of corroborating experiments by Richard Garwin, Leon Lederman, and Marcel Weinrich in Physical Review.
Cobalt-60 is a synthetic radioactive isotope of cobalt. Because of its radioactivity, cobalt-60 has been used for lots of different kinds of experiments – from shattering symmetries of the universe to shattering the hardness of tire treads.
Samuel Gehman testing tire tread hardness following exposure of the tire to intense gamma ray radiation from cobalt-60. The window at upper left is 36 inches thick, made of optically polished high-density glass that permits scientists to see into the irradiation chamber or "cave" while various materials are subjected to radiation. Circa 1957. Credit: AIP Emilio Segrè Visual Archives. Gehman Samuel F1
Quartz shows up on the original chart as February’s birthstone – at least in its purple version Amethyst. (The purple color may be caused by iron impurities.) However, quartz ought to be March’s birthstone because it was in March 1880 that the Curie brothers Pierre and Jacques discovered piezoelectricity.
Before he ever met a woman named Marie Sklodowska, Pierre Curie was conducting experiments with his older brother Jacques on the structure of crystals. They discovered that by putting a crystal of quartz under mechanical strain (literally squishing it), it created an electric potential. Later, they also experimentally confirmed that piezoelectricity works the other way as well – putting an electric potential along a quartz crystal will deform it. Piezoelectricity is an integral component of scientific research today, being used in everything from electrometers to devices which can alter the position of something by nanometers.
Pierre Curie's piezoelectric quartz. Credit: AIP Emilio Segrè Visual Archives, E. Scott Barr Collection. Curie Pierre F1.
Incandescent lightbulbs aren’t as common as they used to be, but I bet a lot of readers are familiar with the characteristic spiral filament. We have Irving Langmuir to thank for this design, which he patented in April 1916. When Langmuir first went to work at General Electric he was directed to solve the problem of blackening lightbulbs. As lightbulbs were used, the inside of the bulb would become cloudy with evaporated tungsten from the filament. To inhibit the vaporization of the tungsten filament, Langmuir developed the characteristic spiral and also suggested filling the bulbs with nitrogen gas. (The nitrogen was later replaced with argon).
The use of tungsten as a filament was invented by his colleague William Coolidge at General Electric. Coolidge also was the inventor of the Coolidge x-ray tube and directed the General Electric Research Lab from 1932-1945. Here he is below on his 100th birthday being presented with a cake lit by 100 tungsten lamps.
Centenary celebration for Dr. William D. Coolidge (center). Coolidge was succeeded by Dr. C. Guy Suits (right), director until 1965, and by Dr. Arthur M. Bueche (left) who became General Electric's vice president when Dr. Suits retired. The birthday cake was lighted with 100 ductile-tungsten lamps and topped by the target from an early Coolidge tube encrusted with 100 tiny diamonds surrounding one of GE's large laboratory-made gem diamonds. Credit: General Electric Research and Development Center, courtesy AIP Emilio Segrè Visual Archives, Physics Today Collection. Coolidge William C1.
It was inevitable that the birthstone for May would be ruby, given that Theodore Maiman created the first optical maser (a.k.a. laser) in May 1960 using an artificial ruby. In a ruby laser, a light source (at top in the photo below) is used to excite the tightly-packed atoms in the ruby which then amplify the laser's light into an intense parallel beam. The ruby is what is called the “gain medium.” Gain mediums need to be of controlled purity (hence why Maiman used an artificial ruby) but do not need to be solid.
Today all sorts of gain mediums are used, including gasses like mixtures of helium and neon. Another birthstone – sapphire – is used in some lasers, as well as YAGs (yttrium aluminum garnet), another variety of garnet that sounds like a fighter jet. (There is also a variation called monoclinic yttrium aluminate or YAM, but I don’t think they’re going to make a Top Gun sequel about that one.)
Getting back on topic, Laser stands for Light Amplification by Stimulated Emission of Radiation. This term was coined not by Maiman but rather by Gordon Gould (shown below) earlier in 1957. To learn more about the history of the laser you can check out the Center for History of Physics web exhibit on the topic.
Gordon Gould (right) and Ben Senitzky (left) at Technical Research Group with a millimeter wave amplifier. Circa 1950. Credit AIP Emilio Segrè Visual Archives, Hecht Collection. Gould Gordon F1.
Superconductors are, in a word, super-cool. (It counts as one word if you hyphenate it.) Unfortunately, that’s part of the problem. Superconducting materials offer the ability to conduct electricity with no resistance, but they must be cooled to very close to absolute zero. For reference, Absolute Zero is 0 Kelvin (or -273 degrees Celsius or -460 degrees Fahrenheit), and the freezing point of water is 273 Kelvin (or 0 Celsius or 32 Fahrenheit).
Portrait of Heike Kamerlingh Onnes sitting in a laboratory, surrounded by scientific equipment. Credit: Rijksmuseum voor de Geschiedenis der Natuurwetenschappen, courtesy AIP Emilio Segrè Visual Archives. Kamerlingh-Onnes Heike A1.
Superconductivity was first discovered in 1911 by Heike Kamerlingh Onnes and his students who found that mercury wire became superconductive around 3.6 Kelvin (K). Over the following decades, various materials were tried, but a limit of around 23.3 K could not be surpassed. Not until, that is, Johannes Georg Bednorz and Karl Alexander Müller started trying copper oxides. Lanthanum barium copper oxide was superconducting at 35 K! (Still pretty cold but a big improvement.) They published their results in June 1986 and other labs swung into action to replicate and improve on their results. The American Physical Society 1987 March meeting which followed their announcement was so energized it has been called the “Woodstock of Physics.”
Karl Alexander Muller and Johannes Bednorz sit in front of equipment. Credit: IBM, courtesy of AIP Emilio Segrè Visual Archives. Muller Karl C2.
Many of these birthstones are rare, some are synthetic, but July’s birthstone has only been created once in all of history. Trinitite is a green glass that is only found at the site of the Trinity Test. It was created on July 16, 1945, when sand from the area surrounding the bomb was drawn up into the fireball and melted (consuming some pieces of debris in the process) before raining down and cooling on the ground. For about a decade it was a very popular pastime to take a piece from the site. In the early 1950s the government excavated and buried over the trinitite, and it subsequently became illegal to take any. However, many pieces can be found in museums, and some which were taken during the legal period can easily be found for sale.
Aerial view of the Trinity Crater after the explosion. July 20, 1945. Credit: Los Alamos National Laboratory, courtesy of AIP Emilio Segrè Visual Archives. Los Alamos Trinity H54.
August’s birthstone is gold, a great deal safer than July’s although also with an interesting connection to atoms. In August 1908, Hans Geiger published the first “gold foil” experiment which he conducted under Ernest Rutherford. There were many gold foil experiments, but this was the first. These experiments, also called the Geiger-Marsden experiments, were a driving factor behind the shift away from J. J. Thomson’s “plum pudding.” In the plum pudding model, small negative charges mush around in a larger medium of positive charge (much like the raisins in a plum pudding). Then, in the gold foil experiments, alpha particles were shot at a very thin sheet of gold foil. While most of the particles went through undeflected, some bounced back at absurd angles, indicating that the positive charge of an atom was tightly concentrated and most of the rest of the atom was empty space.
Hans Geiger’s name likely sounds familiar because of his eponymous counter which measures the level of radioactivity by detecting the number of ionized particles present – like alpha particles!
Ernest Rutherford (right) with Hans Geiger (left) who invented, between 1908 and 1913, a simple device for counting alpha-particles one by one, conversing in Schuster Laboratory, University of Manchester, England. Credit: AIP Emilio Segrè Visual Archives, Physics Today Collection. Geiger Hans C1.
September’s birthstone ought to be a familiar one to anyone who closely follows the photos of the month. Take a quick look back at September’s Photos of the Month and you’ll see it’s all about the study of the Earth’s structure. That post (and this month’s birthstone) is in honor of Inge Lehmann and her groundbreaking paper, published in September 1936, which showed that the Earth has a solid inner core. And since a 1952 paper by geophysicist Francis Birch, it is widely thought that the inner core is likely crystalline iron.
Formal portrait of Inge Lehmann. Photo by Peter Elfelt, American Geophysical Union (AGU), courtesy AIP Emilio Segrè Visual Archives. Lehmann Inge A1
As we’ve talked about on this blog before, Robert Williams Wood was an eccentric scientist with an eclectic set of research interests. However, he definitely had a special love for optics. In October 1910 Wood published the first infrared photographs. He used a filter he had invented in 1903, now called “Wood’s glass.” With long exposures, the filter also permitted infrared photographs. Wood’s glass also transmitted ultraviolet light even as it blocked visible light, enabling Wood to take the first photos of ultraviolet fluorescence as well.
Robert Williams Wood as graduate student in Berlin, doing spectroscopic research. Credit: AIP Emilio Segrè Visual Archives. Wood Robert Williams F2
Wood’s glass became the basis for blacklights, and today filters for infrared and ultraviolet light have a myriad of applications in physics and astronomy. In the photo below, a scientist from Bell Labs uses ultraviolet light to investigate laser crystals. Fluorescence of the crystal indicates that it may produce laser action. When lasing, this fluorescence is 'harnessed' and emitted as a high intensity beam of coherent, monochromatic light. The crystal shown in L.G. Van Uitert's hands is a scheelite, which was pulled from a melt at Bell Laboratories.
LeGrand G. Uitert investigates laser crystals in ultraviolet light. Credit: Bell Laboratories / Alcatel-Lucent USA Inc., courtesy AIP Emilio Segrè Visual Archives, Hecht Collection. Van Uitert L G F1.
The diamond is usually April’s birthstone, but in honor of Henry Rowland’s ruling machine let’s declare it for November instead. Henry Rowland was one of the most influential physicists of the late 19th century United States, and one of the major persons responsible for making it a recognizable profession. He was also incredibly important for the development of astrophysics because of his ruling machine.
A ruling machine creates the very regular, very closely spaced, parallel lines on a diffraction grating. The lines on the grating separate light by wavelength, allowing scientists to measure the spectrum of a particular light source. As you can imagine, good gratings are incredibly important for the study of spectra in astrophysics! The better the grating, the more detailed or complete spectrum that can be studied. And the quality of the grating depends on the quality of the ruling machine that made it. The first ruling machines were made by David Rittenhouse in 1785 and Joseph von Fraunhofer in 1821 from threading hairs between two screws. Unfortunately, until the late 1800s, spectroscopy was limited in its efficacy by problems in spectral gratings like “ghosts” on the imaging plates which is caused by the periodicity of the grating.
Henry Rowland and his ruling machine. Credit The Johns Hopkins University Archives, courtesy of AIP Emilio Segrè Visual Archives. Rowland Henry F1
Henry Rowland developed a new kind of ruling machine, which used the turning of a screw to minutely score lines with a diamond tipped ruler. This enabled many more lines to be drawn in a linear inch. Another major innovation was Rowland’s use of spherical concave gratings which made them self-focusing. This reduced the need for additional focusing lenses which would absorb part of the spectrum.
Rowland debuted the first spherical gratings made with his diamond-tipped ruling machine at the November 1883 meeting of the London physical society. His diffraction gratings were incredibly popular, and he gave away many or sold them at cost to scientists around the world. Many, many, diamonds were worn down making these important gratings, and so they are the official birthstone of November.
The final birthstone is graphite, for the month of December. This one likely needs little explanation, because the story of the world’s first self-sustaining nuclear reaction has been told many times. The reaction occurred on December 2, 1942, at the University of Chicago underneath Stagg Field.
To simplify the explanation a bit, nuclear reactions are all about speed. If you get a lot of radioactive material in one place, as each atom decays it fires off a neutron or two that will hit another atom, causing a chain reaction. If you have nothing to slow down the neutrons whizzing about, the chain reaction will happen too fast, and there will be an explosion of energy. Also known as a bomb.
Graphite pile at Stagg Field. Credit: University of Chicago, courtesy AIP Emilio Segrè Visual Archives. University of Chicago H10.
This is where graphite comes in. Graphite slows down the neutrons so they impact the other radioactive atoms at a rate fast enough to keep the chain reaction going but not too fast to cause an explosion. The first self-sustaining nuclear reaction used literal tons of the stuff as shown in the image above. To quote the longer caption that accompanies the image:
“This is the only photograph made during the construction of the first nuclear reactor. The photograph was made in November, 1942 as the 19th layer of graphite was being added. Alternative layers of graphite contained uranium metal and uranium oxide and were spaced by layers of ‘dead’ graphite. Layer 18, almost covered in this photograph, contained uranium. Actual construction was carried on in this manner to the 57th layer which was about one layer beyond the critical or operating dimensions. The roughly spherical form of the structure is shown as is some of the supporting framework. The reactor was constructed as West Stands, Stagg Field, University of Chicago, and was operated for the first time on December 2, 1942.”
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