Earth is the homeworld of the Human race, located in the Sol System. It is the third planet of the system, orbiting at precisely 1 AU from its parent star, a G2-V Main Sequence star known as Sol, or simply The Sun. Contrary to popular belief, Earth is not the Federation's headquarters - it is Mars.
Exposure to. vertical vibrations in the 5-10 Hz range generally causes resonance in the thoracic-abdominal system, at 20-30. Hz in the head-neck-shoulder system, and at 60-90 Hz in the eyeball. When vibrations are attenuated in the. body, its energy is absorbed by the tissue and organs. The muscles are important in this respect. Vibration. leads to both voluntary and involuntary contractions of muscles, and can cause local muscle fatigue, particularly when the vibration is at the resonant-frequency level.
A body that becomes overly stressed (stress-response hyperstimulated) can cause the nervous system to behave erratically, which can cause nerve impulses to fire erratically. Since nerve impulses control muscles, an erratically behaving nervous system can cause muscles to twitch. As long as the nervous system is even slightly overly stressed, it can cause erratic muscle twitching.