Lobes of the brainThe lobes of the brain are the major identifiable zones of the cerebral cortex, and they comprise the surface of each hemisphere of the cerebrum. The two hemispheres are roughly symmetrical in structure, and are connected by the corpus callosum. They traditionally have been divided into four lobes, but are today considered as having six lobes each. The lobes are large areas that are anatomically distinguishable, and are also functionally distinct to some degree.
Reaction engineA reaction engine is an engine or motor that produces thrust by expelling reaction mass (reaction propulsion), in accordance with Newton's third law of motion. This law of motion is commonly paraphrased as: "For every action force there is an equal, but opposite, reaction force." Examples include jet engines, rocket engines, pump-jets, and more uncommon variations such as Hall effect thrusters, ion drives, mass drivers, and nuclear pulse propulsion.
Existential crisisIn psychology and psychotherapy, existential crises are inner conflicts characterized by the impression that life lacks meaning or by confusion about one's personal identity. Existential crises are accompanied by anxiety and stress, often to such a degree that they disturb one's normal functioning in everyday life and lead to depression. Their negative attitude towards life and meaning reflects various positions characteristic of the philosophical movement known as existentialism.
