1976
An Electron-Hole Liquid
“Recently scientists have discovered that the carriers of electric charge inside a crystal can exist in a state that has many of the properties associated with water. For instance, it can exist as a vapor, and when the relative humidity becomes high enough, the particles condense. Unlike water, the new liquid exists only inside a solid semiconductor, and it cannot be extracted from that environment. Instead of the atoms or molecules of an ordinary liquid, it consists of electrons and ‘holes,’ or the positively charged voids formed by the absence of an electron. The electrons and holes continually annihilate each other and, in the process, give off infrared radiation. As a result, the liquid is inherently unstable; it disappears in a fraction of a second without a continual supply of electrons and holes.
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“Finally, the new liquid is essentially a quantum-mechanical fluid. Effects that are negligible in conventional fluids have a major influence on the electron-hole liquid. For these reasons the new liquid offers a unique testing ground for some of the fundamental principles of physics.”
1926
How to Observe Sunspots
“For the last year or two, the number of sunspots has been rapidly increasing, as well as their size. It is not unusual for a spot, or spot group, to be large enough to be seen with the unaided eye. ‘Unaided’ is rather a misnomer, for no sane man would think of looking at the sun without some protective device, either the old-fashioned smoked glass or the more modern piece of densely fogged film. With this simple equipment, the amateur may see the spots and observe their stately progress across the sun’s disk from day to day as the rotation carries them onward.”
Is Earth’s Interior Molten?
“Man has never been able to penetrate much more than one mile beneath Earth’s surface—a mere pinprick. Yet, while science does not claim positive assurance regarding the actual conditions in Earth’s inner layers, there are certain things about it which we know are not so. One is that Earth’s interior is a molten liquid. Probably nothing has tended so strongly to crystallize this widespread misconception as the existence of volcanoes, pouring out liquid lava. In Earth’s center, however, the pressure is too great for the rocks to melt. Thus, they are as rigid as steel. Seismologists can easily prove the latter statement, for they record earthquake shocks that travel through Earth’s interior; the characteristics of these shocks prove the interior to be rigid. Volcanoes are held by the majority to be of local, not deep-seated origin.”
In 1936 a foundational paper described for the first time the existence of Earth’s solid inner core surrounded by a liquid outer core.
Eavesdropping on the Arctic
“There is no east, west or north at the top of the world, and therefore thousands of short-wave radio receivers on all sides of Earth will have an equal opportunity to tune in the messages broadcast by the aviator-explorers participating in the race to the North Pole this summer.
“The ethereal channels originating in the ice-capped region will be sprayed across the globe. Twelve Arctic expeditions are in preparation, and three are ready to hop off from northern points of land into the cradle of storms. Newspaper reporters, accompanied by radio operators and wireless equipment, have established a base at Point Barrow, Alaska, from where they hope to pick up radio signals and then relay the greatest news story of the year. It is expected that many amateurs operating short-wave sets will hear the narrative firsthand from the explorers within a fraction of a second after the words are released into the northern air because low wavelengths skip over short distances and travel far.”
1876
Door-Building Spiders
“In the Paris Jardin de Plantes [a botanical garden in France], there is a curious spider belonging to the Mygale genus. Like all spiders, this strange creature has eight eyes. Its mandibles are armed with sharp teeth, and its feet have retractile claws, resembling those of a cat.
“The most curious member is indigenous to Corsica, a light brown spider that lies in tubes dug in clay banks. The tubes are vaulted from end to end with a hard mortar, and this in turn is lined with a soft, silky web. Before, however, covering his walls with their finest hangings, the spider fastens up a coarse fabric, and on this, as a foundation, the more delicate material is secured. Then he begins the construction of his door, in which operation it would seem that almost reasoning faculties are employed. Although scarcely one tenth of an inch thick, this door is constructed of upward of 30 alternate layers of web and mortar, each layer being imbedded in another, like a series of cups.”
