After a time, a cloud containing some of such debris condensed under ITS gravity to form our Sun, and its planets including ours.
Our planet, which would have cooled to its present state in fewer than a hundred million years but for such massive elements, has stayed internally alive and molten with the radioactivity of the most enduring of these large nuclei, thorium and uranium, and also the rather surprisingly long lived radioactive isotope 40 of potassium.
It has done so for about 4,540 million years, a fact known from the rates at which known radioactive isotopes turn into different elements as they "decay".
It would have gone cold in fewer than a hundred million without them.
Neither the drifting continents nor, probably, life on Earth, could exist but for the energy from the deaths of these super stars.
Earth's radioactive heat provides us with a magnetic field, geothermal energy, continental drift, earthquakes, volcanos, and tsunamis. The Sun provides us with the energy for photosynthesis, fresh water, tornados, hurricanes, and typhoons.
Jupiter's enormous magnetic field is probably powered by nuclear fusion, as of course is the Sun.
The techniques for releasing even more of the energy of the atomic nucleus were developed in the 1940s and 1950s, first for warfare, and then for peaceful uses. A large number of people seem to be unable in their minds to separate these very distinct and different uses. The difference between a reactor and a bomb is bigger than the difference between a gasoline engine and a "Molotov cocktail".
The research funded, in at least five countries, by the realisation that WE had better have such a bomb when THEY get one, has been made available for better purposes.
The converse is not true.
Reactor grade plutonium, even when chemically pure, can only be made to explode by people who know easier ways to make a bomb. Even then it is a dirty fizzle.
Now perhaps, if we are lucky, the fact that the Chinese “People's Republic” is about to solve the global warming problem and the world's dependency on mere solar fossil energy (carbon, petro-hydrocarbons, and oxygen) using research pioneered by the West, will wake us up to the inadequacy of wind, sun, biomass, and even the snow and rain on the high mountains.
If not, then if the world is very lucky, Norway or India will effectively develop and export thorium-to-uranium breeder reactors to our grandchildren. The mission given to the study group in Norway used an interesting adjectival phrase. They were to produce a report that would be "knowledge-based". That may be a literal English translation of a peculiarly Norwegian word, but I at first thought it superfluous. Then I realised how much of nuclear energy reporting and analysis is quite grossly "ignorance-based".
Safe, plentiful civilian nuclear power is to my mind the only way to avoid major war over energy resources in this century. Why else did the USA bomb Iraq and merely ostracise Iran?
Footnote: The Sun's primary energy production comes from conversion of four hydrogen atoms (their nuclei, to be precise) into a helium nucleus.
0.72% of the mass of the hydrogen becomes energy.
The Sun will have to resort to other processes when it has "burned up" less than one percent of its mass.
It will probably become a "Red Giant".
It takes far higher energies, produced by gravitational pressure and collisions, to fuse pairs of helium nuclei. Carbon is made by the fusion of triplets of helium nuclei. But in fairly modest stars slightly larger than ours, the processes produce everything from lithium to neon, and beyond.
For very large stars, the fusion processes and the speed and chaos of the demise are what create nuclei that contain more energy than a nearly equivalent mass of two less massive nuclei. The fusion process, driven by gravitational energy, is described as occurring in seconds. Most of that energy is the gravitational energy of the collapse.