Useful fiction

At this point, the variables C and u are now used to connote the average (macroscopic) tracer concentration and velocity, respectively, and the overbar is dropped for convenience. Implicit in this formulation is the belief that fundamentally Lagrangian (particle) dispersion can be modeled as a continuum Eulerian phenomenon in a fashion analogous to the Fickian formulation of molecular transport by Brownian motion. This is a useful fiction for simple modeling exercises, but must be used with caution (see the next section on isopycnal diffusion). 

Baeyer s speech has considerable interest. After the expected preliminaries, he began by asking the rhetorical question Is Kekule s benzene theory a true depiction of the molecule, or is it simply a heuristically useful fiction This question evoked a consideration of molecular models. Van t Hoff was not the first to suggest a tetrahedral shape for the carbon atom, Baeyer noted it was Kekule who had introduced tetrahedral carbon models in 1867. Of course, van t Hoff had taken the idea further than Kekule, in particular by affirming that the four valence bonds emanating from each carbon atom were relatively fixed and could therefore be studied chemically. In this sense Kekule s tetrahedral models were analogous to Heinrich Hertz s famous comment about James Clerk Maxwell s equations of the electromagnetic field that they have almost an independent life, that they can appear wiser even than their creator and can yield more than was ever invested in them. ... 

From all the mentioned examples we can conclude that there are very few reaction mechanisms that have been determined beyond reasonable doubt . In his lecture to the Croatian Chemical Society in Zagreb, the late Professor Ronald S. Nyholm (University College London) commented Kinetics are facts, mechanisms are fictions , but we can add - very interesting and useful fictions. 

Topics are Female alchemists Aelia Laelia Crispis Practical alchemy Historical alchemy related sites in the Czech Republic Image and Will in alchemy Gender in alchemy David Hudson - the White Powder Gold The use of blood in Alchemy The Symbolism of the Rose in Alchemy The Caduceus and Religion Relevance of Alchemy Islamic alchemy Armand Barbault The Golem Abraham the Jew and Flamel Alchemical fiction Animal alchemy Differences between Alchemy and Magic ... 

Boldereff, Frances Motz. Hermes to his son Thoth being Joyce s use of Giordano Bruno in Finnegans Wake. Woodward (PA) Classic Non-Fiction Library, 1968. 289p. 

Whether for a dramatic scene or a science-fiction fantasy, the use of artificial fog to create ambience and special effects is commonplace in theatrical and film productions. On what basic chemical principles do fog machines operate ... 

In America, George Washington was a hemp farmer, although it seems that there was little knowledge of the intoxicating properties of the plant until Mexican immigrants later introduced social consumption of the plant. By the 19th century, cannabis use had spread from the Middle East to the artists and writers of Europe, most notably by Le Club des Haschischins (The Club of Hashish Eaters) in Paris, and as a result popular fiction also raised the profile of cannabis use thanks to the... 

Taking a value of 107 for N would mean that in our galaxy (with its perhaps 100 billion stars), there could be several million planets with life forms capable of interstellar communication. However, if these were distributed statistically, the nearest would still be 200 light years away from Earth. One point is important the term probability used in the Drake equation is interpreted in the sense of subjective probability (a term from the nomenclature used by statisticians and probability theorists), as the numerical value of this probability is determined only by the experience of the scientist concerned (Casti, 1989). Casti also provides more information on the Drake factors (apart from the factor fs) in the chapter Where are they then In summary, we can say that the Drake equation is a first attempt to quantify the ETI problem in order to move from the area of science fiction and pure speculation to that of serious scientific debate. 

The Moon Metal was published in 1900 after the discoveries of radiation, X-rays, and cathode rays. Then, perhaps due to its increasing relevance after the discovery of atomic transmutation by Rutherford and Soddy at McGill in 1901-1902, it was republished in a magazine in 1905. Serviss explores the implications of the mysterious science of cathode rays for the world economy by using conventions from gothic fiction—including the sinister and mysterious villain who seems to use occult powers, and alchemy in particular, to further his nefarious schemes. 

---