The Sun Relies on Quantum Tunneling for Fusion

The Sun core is insanely hot, yet fusing nuclei is still hard. Positively charged nuclei repel each other strongly. Classical physics would demand even higher energies to overcome the barrier. Quantum mechanics allows a probability to tunnel through it. That tiny probability becomes powerful when multiplied by huge numbers of particles. Fusion proceeds, releasing heat and light. Even the most familiar light in our lives depends on quantum rules. One of quantum theory greatest gifts is the stars overhead.