Inventions and science

Science gets its name from the Latin word scientia, “knowledge”. Science is based on observation, experiments and evidence. Branches: physics, chemistry, biology, astronomy, geology. The universe is thought to have begun about 13.8 billion years ago with the Big Bang, and the Earth is about 4.5 billion years old. To express certainty and possibility we use modal verbs: must be – almost sure (The lights are on. They must be at home); may / might / could be – possible (It may rain. That could be a comet). The verb after them is in the base form: may know, might come. Maybe, perhaps and probably also show possibility. Imaginary condition: If I were an astronomer, I would study the stars. (If ... were ..., ... would + verb).