AERODYNAMICS
Aerodynamics is the study of designing objects so that they will go smoothly through the air, rather than having to constantly waste energy battering through air resistance.
In the early days of flight, aerodynamics was a somewhat informal science, and advances in engine power that gave aircraft more brute-force ability to push through the air were often more important. This began to change in the 1920s and 1930s, when aerodynamic designs became more popular not only for monocoque-hulled aircraft, but also for trains and automobiles.
Aerodynamics became all the more important when engineers attempted to design more complex and advanced aircraft, such as helicopters (which are inherently unstable, and must be designed carefully to be flyable) and supersonic jets (since passing the speed of sound can rip an aircraft to pieces if the design fails to deflect and make use of shockwaves created by breaking the sound barrier).
Today, aerodynamic calculations can be made in greater detail and thoroughness than ever before, using powerful computers. This allows designers to extract the greatest possible speed and efficiency out of a given amount of engine power.
ALCHEMY
Alchemy is the study of chemical substances, in its pre-scientific form.
This was often an informal art; mysticism and superstition were mixed seamlessly with pragmatic efforts to manipulate flame, metal, and liquids. Many alchemists sought out impossible goals such as the universal solvent, the elixir of youth, the secret of immortality, or means by which common metals like iron or lead might be transmuted into gold. Alchemy was fraught with frauds, cheats, and liars.
However, alchemists made real contributions to society. Alchemists were the first to invent many of the basic techniques of processing chemicals, and the equipment needed to do so. Operating on a rough-and-ready empirical basis, they were able to develop substances such as acids, distilled alcoholic spirits, incendiaries, and gunpowder, which had great effects on their societies in both war and peace.
ATOMIC PHYSICS
Atomic theory is, in simplest form, the idea that all matter is made up of tiny, indivisible particles called "atoms."
The first ancient form of this theory comes from the Greek philosopher Democritus. His atomic theory was founded on the Greek ideas of the geometric order of the universe and of the four elements, which led to some strange ideas. For instance, early supporters of the atomic theory suggested that water might flow because it was made up of icosahedral atoms which, being nearly round, tumbled over each other easily; fire was painful because it was made up of tetrahedral atoms which were sharp and thus damaging. Since there was no evidence for this theory at the time, and no obvious reason to prefer it to the alternatives, it was largely ignored for the following two thousand years.
The atomic theory re-emerged around 1800, following early chemists' discovery of new types of chemical elements that seemed more fundamental than things like air and fire. The chemist John Dalton proposed again that all matter was made of atoms, which were neither created nor destroyed in chemical reactions, only reshuffled to form different substances. This theory proved fruitful for 19th century chemistry, although many scientists insisted that it was only a theory.
Towards the end of the century, advances in the studies of the spectrum of light emitted by different elements, and the discovery of radioactivity, cast doubt on the premise that atoms were indivisible. Perhaps atoms had some kind of internal structure, and were themselves composed of smaller particles with new and intriguing properties of their own. The first of these particles to be discovered was the electron, a tiny and lightweight particle which carries a strong negative charge, and whose motions form the basis for nearly all electrical, magnetic, and chemical interactions.
Further investigation into the structure of the atom using ever more precise and complex instruments and mathematical theories opened up broad vistas of scientific discovery. Various models of atomic structure, such as the "plum pudding" model, the Rutherford atom, and the Bohr atom, were considered, modified, or discarded. Scientists gained more understanding of the mechanisms behind atomic structure, and of how atoms could bind together to form molecules.
This led to great advances in practical technology in the latter half of the 20th century. Once the atoms that made them up were understood, chemists could tailor-make molecules to suit their needs. Alloys with strange electrical properties could be used to build advanced calculating machines. And the immense forces locked within the atomic nucleus could be released, for good or for evil.
. Makes it a little harder, though, to control the pace of advancement to avoid anachronisms through more AND prereqs, because it would mess up the graphical looks of the tech tree
