Gravity had kick-started the transformation of matter into stars by fusing protons despite the barrier created by their positive charges. This is a pattern we will see over and over again. It’s a bit like the cup of coffee that helps you get going in the morning. Chemists refer to this initial shot of energy as activation energy; it’s the energy of a lit match that starts a conflagration. One kind of energy changes something so as to release other flows of free energy that are much greater than the activation energy. In the story of star formation, gravity provided the activation energy for
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