There are no cars or airplanes, but there are plenty of trains and zeppelins.
Internal Combustion EnginesEdit
Aua is a large planet and rich in many ways. However, what it is lacking is a plentiful resource that can be used as fuel for internal combustion engines. The principle of the internal combustion engine is known and has been proven to work very well in practice. However, the avialability of reliable fuel is such that driving a car is too expensive and dangerous for it to be a viable solution for most kinds of transportation.
What this means is that the car as we know it does not exist (more on electrical cars later). There are also no airplanes like the ones commonly used for commercial transport in the real world. The same goes for ships.
Since the invention of the combustion engine, scientists have been searching frantically for reliable source of fuel. Multiple kinds of fossil and vegetable fules and mixes of the two have been tried. Attempts to magically enchant various substances to serve as fuel have also been attempeted with varying degrees of success. These enchanted types of fuels are commonly referred to as arcane fuels.
Early on in the search for reliable fuel a material property called Critical Instability Frequency (CIF) was discovered. The Critical Instability of a type of fuel will cause it to react with aether when the engine reaches a certain number of Revolutions Per Minute (RPM). These reactions are often violent and destructive and even in the best of cases lead to the destruction of the engine. Needless to say this is not something that you want to happen while driving a car, or any other type of vehicle.
Reasearch into reliable and cost efficient fuel is ongoing but no breakthrough has yet been made.
As with all things there are exceptions. Engines that work at very low speeds, such as Hot Bulb Engines which run at 50 to 300 rpm, are not impacted as much by Critical Instability. It's been found that certain fuels based on vegetable oils provide enough energy to power such an engine without risking Critical Instability.
Engines like these aren't very useful when speed is a factor though. They're mostly used in tractors, fishing boats and suchlike.
The turbine engine is a type of Internal Combustion Engine but it uses continuous rather than intermittent combustion. This means that critical instabilite is not an issue for turbine engines. However, the availability of cost efficient fuel is still an issue. The costs involved with running turbine engines mean they're really only used in cases where money isn't much of an issue, such as in countries spending lots of money on their armies.
Engines powered by electricty are not affected by critical instability and have proven to be both reliable and efficient. However, due to the inefficiency of batteries an external power source is a practical requirement. This is not an issue for electric trains, but has so far proven to be an absolute show-stopper for electric cars.
Battery powered engines see some use in airships though, where the lift isn't dependent on the engine and the size of the battery is less of an issue.
- Steam power