The age, history, and possible fate of the universe

Evidence for the Big Bang built up over the twentieth century: in 1929 Edwin Hubble showed that more distant galaxies are moving away faster, meaning the universe is expanding, and in 1965 Arno Penzias and Robert Wilson discovered the cosmic microwave background, the leftover glow of the hot early universe. Measurements of that background and of the expansion rate give the universe an age of about 13.8 billion years. Its history runs from an extremely hot, dense beginning, through the first few minutes, when hydrogen and helium nuclei formed, to about 380,000 years, when atoms formed and the cosmic microwave background light was released, to the first stars and galaxies a few hundred million years later, which grew through mergers into the galaxies we see today; our solar system formed about 4.6 billion years ago. The universe's fate depends on its contents. A closed universe, with enough matter, would eventually stop expanding and collapse; an open universe would expand forever. Measurements show the universe is very close to geometrically flat, and dark energy is accelerating the expansion, so the current best evidence points to expansion continuing forever as the universe grows ever colder and emptier, though because dark energy is not understood, its future is still an open question.

This explanation is AI-generated and can occasionally be wrong. 🚩 Report