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There are some subtle facts about scale analysis that make it more powerful than simply comparing orders of magnitude. A most remarkable example is that scale analysis can be applied, through a systematic use of dimensions, even when the precise equations governing the dynamics of a system are not known. The great…
Social networks allow people to connect with each other and have conversations on a wide variety of topics. However, users tend to connect with like-minded people and read agreeable information, a behavior that leads to group polarization. Motivated by this scenario, we study how to take advantage of partial homophily…
One of the interesting things to me about our spaceship is that it is a mechanical vehicle, just as is an automobile. If you own an automobile, you realize that you must put oil and gas into it, and you must put water in the radiator and take care of the car as a whole. You begin to develop quite a little…
The name "ideonexus" is not an English word, but it is a combination of two words: "ideo" and "nexus." The "ideo" is a version of the word "idea" (想法) that we use in compound words, like "ideology." The word "nexus" means "intersection" (路口), "relationship" (关系), or "connection" (连接). So the name "ideonexus" is…
"Cultural populists," . . . generally view popular culture as contested terrain in which individuals and groups (racial, ethnic, gender, class, etc.) struggle, albeit on unequal terms, to make and establish their own meanings and identities. As the populists see things, the consumers of cultural commodities (movies…
Two and a half million years ago, our small-brained ancestors evolved the ability to knock flakes from rocks to use as cutting edges. By doing so, they could also make the rocks themselves useful as choppers. This basic tool kit of flakes and choppers served the needs of hunting and gathering for a million years…
The O’Neill cylinder is named after an American physicist and space scientist who sought to engage his students by getting them to think about big problems—space settlement, in particular. He also led symposiums where the concepts behind large, permanent space habitats—including the cylinder that bears his name—were…
Ferromagnetic materials are paramagnetic materials. Below the Curie temperature ferromagnetic materials show spontaneous magnetization, and this means that the spin moments of neighboring atoms in a microscopically large region (called domain) result in a parallel alignment of moments. The application of an external…
...you need fewer art assets to build a simple puzzle game. This is very good news for small developers, and for those just starting out in gaming. One or two people can build a world-class puzzle game. It would be next to impossible for one or two people to build a world-class third-person action game from scratch…
Thanks for your petition. There’s a lot of history here. Right after the Civil War, President Andrew Johnson signed legislation that made it "lawful throughout the United States of America to employ the weights and measures of the metric system in all contracts, dealings or court proceedings." In 1875, the United…
With the hefty biomass created by a marsh, you can then build up land using some of your excavated materials, saved on the surface of the asteroid for this moment. Hills and mountains look great and add texture, so be bold! This process will redirect your water into new hydrologies, and this is the best time to…
On the black hemisphere, Cassini Regio, the bulge bisects an area where people once upon a time went out in hoppers or rovers and blew the black dust away to make patterns out of exposed white ice. Anytime you can easily make such a contrast in the landscape, people have written out their thoughts for the universe to…
As the statistician George E. P. Box wrote, “All models are wrong, but some models are useful.”90 What he meant by that is that all models are simplifications of the universe, as they must necessarily be. As another mathematician said, “The best model of a cat is a cat.”91 Everything else is leaving out some sort of…
This meant, then, that the Greeks, in attempting to communicate their mathematical conceptioning, defined the circle as "an area bound by a closed line of equal radius from one point," the triangle as "an area bo)ound by a closed line of three angles, three edges, and three vertices." The Greeks talked only of the…
In the course of a redshift survey of galaxies brighter than R approximately equal to 16.3, 133 redshifts were measured in three fields, each separated by roughly 35 deg from the other two. If the galaxies in these fields were distributed uniformly, the combination of a galaxian luminosity function and the magnitude…
Lecturing after a fashion is easy enough ; teaching is a very different affair. ... The transmission of ideas from one mind to another, in a simple unequivocal form, is not always easy ; but in teaching, the object is not merely to convey the idea, but to give a lively and lasting impression; something that should not…
We can see that there is only one substance in the universe and that man is the most perfect one. He is to the ape and the cleverest animals what Huygens's planetary clock is to one of Julien Leroy's watches. If it took more instruments, more cogs, more springs to show or tell the time, if it took Vaucanson more…
We called the new [fourth] quark the “charmed quark” because we were pleased, and fascinated by the symmetry it brought to the subnuclear world. “Charm” also means a “a magical device to avert evil,” and in 1970 it was realized that the old three quark theory ran into very serious problems. ... As if by magic the…
The occurrence of an internal skeleton, in definite relations to the other organ systems, and the articulation of the body into homologous segments, are points in the general organization of Vertebrates to which especial weight must be given. This metameric structure is more or less definitely expressed in most of the…
That this subject [of imaginary magnitudes] has hitherto been considered from the wrong point of view and surrounded by a mysterious obscurity, is to be attributed largely to an ill-adapted notation. If, for example, 1, -1, and the square root of -1 had been called direct, inverse and lateral units, instead of…