As for Albert Einstein and the Sun---
Einstein's Mass to Energy equation is basic to the understanding of nuclear power, and provides the solution to the biggest problem known to the 19th century's greatest expert on thermodynamics and energy, Lord Kelvin. He was very puzzled about how the sun could have continued pouring out the energy that he calculated as "the Horsepower of the Sun".
Quite simply, the mass difference between four hydrogen nuclei and one helium nucleus is about one percent of the mass. The Sun's core slams one, two, three, then four hydrogen nuclei together, over quite a long time, and emits the mass difference as radiant energy, probably gamma rays in the innermost layers.
But we have available to us on Earth the products of far more violent activity, and it has kept our planet's core molten for almost a hundred times as long as Kelvin gallantly and laboriously estimated. When a star goes supernova, the gravitational energy of its collapsing mass synthesizes elemental nuclei that are more massive than the products of their fission. Instead of stored photosynthetic energy, which is fossil carbon, nuclear fissile isotopes, and those that can be made so, are the "fossil" remains of giant stars.
The US Navy powers its capital ships with fuel that lasts for three years or more, and fits in a very compact space, even counting the shielding. It is vastly safer to be one of the crew of a nuclear powered submarine, than the old oil-fueled ones. It is also more comfortable, even on amazingly long underwater voyages that in the not very distant past were hopelessly impossible.
Abu Dhabi bought the QE2 from its British owners. If they could fit her with nuclear engines, they could sail her again.
