The birth of the stars (500 million years after the Big Bang) – Guido Tonelli /Courier TV
The fifth day lasts 500 million years: it will take a long time for the first star to be born: a small non-uniformity begins to attract protons, hydrogen nuclei, helium nuclei. To act decisively is gravity, the weakest of the forces in the universe at that moment. Gravity compresses matter to the point of triggering nuclear fusion. The star is a titanic clash between gravity and the strong force generated by nuclear mergers. The outcome of this clash is marked: sooner or later, gravity will win. But in the meantime, light and heat emerge from that clash: decisive components also for our existence.