2015-04-17 BBC:星光七纪元-26（在线收听）

 That’s why what we physicists called pressure. This pressure is created as the particles jostle for position. It’s a principle of Quantum Mechanics and when it was applying to stars, the lives of dead white dwarfs suddenly made sense. What stopped them collapsing completely was the gravity which was resisted by the pressure generated between the particles themselves. In a white dwarf, you got a delicate balance between the gravity which was trying to squeeze it together and the pressure of these electrons, trying up to all, have their addresses in the same place that are trying to push out. And it’s a balance between this gravity pulling in and electrons’ pushing out that keeps the white dwarf the size it is. It’s also what lets the star with no fuel supply shine for billions of years. These white dwarfs are very small so they got very small surface area, which means although they are white hot, the light they emit, the heat energy which they send out is still very limited just because of the very small size of the surface. Now it carries on, radiating light and gradually cools down, gradually gets dimmer and dimmer. It’s a little bit like a retired person sitting in an old star’s home. It’s still, you know, ticking alone but gradually gets sort of slower and slower, dimmer and dimmer. There are white dwarfs cluttering up our galaxy, all the other galaxies.