CINDERENDA and the DEATH of STARS (the life and fate of stars)

Abstract

“The story of the Universe has been a long one, and will be longer still,” continued the Storyteller. “The Universe began small and has expanded for billions of years. It is far from ended and will expand for many billions of years to come. Perhaps it will expand forever. It all depends.”

“Depends on what?” asked Joseph.

“It depends on gravity, as does so much in the Universe. The galaxies are all rushing apart as space expands. Gravity is working to slow down this dispersion, as every galaxy tugs on the gravitational bonds it has with its companions, and attempts to rein in their mad flight. In this the galaxies may or may not succeed. If there is enough mass in the Universe, and the pull of gravity is sufficiently strong, then the growth of the Universe will slow down and eventually reverse, with the galaxies then heading back toward one another. This is like the case of a ball that you have thrown high in the air, but gravity will eventually halt its rise and bring it falling back to Earth.

“If there is not enough matter in the Universe, then the bonds of gravity will be too weak, and the expansion of the Universe will continue forever This is more like the case of a rocket fired upward with more than the Earth’s escape velocity. Gravity could not hold it, and it would leave the Earth completely.

“If the Universe is to have such an indefinite future of ever-expanding space, you might ask, what is to become of the stars? At present, the Sun warms us during the day, and at night we can still see the stars shining brightly in the sky It may not always be so. Prepare yourselves now to hear the forbidding story of ‘Cinderenda and the Death of Stars’“