Quantum Tunneling Enables the Sun to Shine
Without quantum tunneling, the Sun wouldn't have enough energy to fuse hydrogen atoms. This quantum effect allows particles to overcome energy barriers they classically shouldn't be able to cross.
About this fact
The Sun's ability to shine depends on a bizarre quantum mechanical phenomenon called quantum tunneling. For nuclear fusion to occur in the Sun's core, hydrogen nuclei (protons) must overcome the strong electromagnetic repulsion between them to get close enough to fuse. However, the temperature and pressure in the Sun's core provide only about 1/10th of the energy needed to overcome this barrier classically. Quantum tunneling allows particles to 'tunnel' through energy barriers they shouldn't classically be able to cross. In the Sun, protons can tunnel through the electromagnetic barrier and fuse into helium, releasing enormous amounts of energy. Without this quantum effect, the Sun would need to be about 10 times hotter to sustain fusion, which would make it uninhabitable for life on Earth. Quantum tunneling is fundamental to stellar nucleosynthesis and the existence of complex elements in the universe.