I need people to understand that Uranium is an eldritch horror
I'm not talking about radiation, or nuclear weapons, or anything that you can do with uranium, I mean its mere existence on Earth is a reminder of cosmic horrors on a scale you can barely conceive of.
When a nuclear power plant uses Uranium to boil water and spin steam turbines to keep the lights on, they're unleashing the fossilized energy of the destroyed heart of an undead star.
In the beginning, there were hydrogen and helium. The primordial fires of the Big Bang produced almost exclusively the two lightest elements, along with a minuscule trace of lithium. It was a start, but that's not much to build a universe out of. Fortunately, the universe is full of element factories. We call them "stars".
Stars are powered by nuclear fusion, smooshing light elements together to make heavier elements, and releasing tremendous amounts of energy in the process, powering the star and making it shine. This goes on for millions to billions of years depending on the stars mass (although not how you might think, the bigger stars die young), the vast majority of that time spent fusing hydrogen into yet more helium. Eventually, the hydrogen in the core starts to run low, and if the star is massive enough it starts to fuse helium into carbon, then oxygen, neon, and so on up through successively heavier elements.
There's a limit to this though:
This chart shows how much energy is released if you were to create a given element/isotope out of the raw protons and neutrons that make it up, the Nuclear Binding Energy. Like in everyday life, rolling downhill on this chart releases energy. So, starting from hydrogen on the far left you can rapidly drop down to helium-4 releasing a ton of energy, and then from there to carbon-12 releasing a fair bit more.
But, at the bottom of this curve is iron-56, the most stable isotope. This is the most efficient way to pack protons and neutrons together, and forming it releases some energy. But once its formed, that's it. You're done. Its already the most stable, you can't get any more energy out of it, and in fact if you want to do anything to it and make it into a different element you're going to have to put energy in.
So, when a massive star's core starts to fill up with iron, the star is doomed. Iron is like ash from the nuclear fire that powers stars, its what's leftover when all the fuel is used up. When this happens, the core of the star isn't producing energy and can't support itself anymore and catastrophically collapses, triggering a supernova explosion which heralds the death of the star.
What kind of stellar-corpse gets left behind depends again on how massive the star is. If its really big, more than ~30 times the mass of the sun and its probably going to form a black hole and whatever was in there is gone for good. But if the star is a bit less massive, between 8-25 solar masses, it leaves behind a marginally less-destroyed corpse.
The immense weight of the outer layers of the star falling down on the core compresses the electrons of the atoms into their nuclei, resulting in them reacting with protons and turning them all into neutrons, which creates a big ball of almost pure neutrons a couple miles across, but containing the entire mass of the star's core, 3-5 sun's worth.
This is the undead heart of the former star: a neutron star.
If, like many stars, this one wasn't alone but had a sibling, it can end up with two neuron stars orbiting each other, like a pair of zombies acting out their former lives. If they get close enough together, their intense gravity warps the fabric of spacetime as they orbit, radiating away their orbital energy as gravitational waves, slowing them down and bringing them closer together until they eventually collide.
The resulting kilonova explosion destroys both of the neutron stars, most likely rendering the majority of what's left into a black hole, but not before throwing out a massive cloud of neutron-rich shrapnel. This elder-god blood-splatter from the collision of the undead hearts of former stars contains massive nuclei with hundreds to thousands of neutrons, the vast majority of which are heinously unstable and decay away in milliseconds or less. Most of their decay products are also unstable and decay quickly as well, eventually falling apart into small enough clusters to be stable and drift off into the universe becoming part of the cosmic dust between the stars.
Some of the resulting massive elements are merely almost stable. They would like to decay, but for quantum-physics reasons decaying is hard and slow for them, so they stick around much longer than you might expect. Uranium is one such element, with U-238 having a half-life of around 4.5 billion years, about the same as the age of the Earth, and its spicier cousin U-235 which still has a respectable 200 million year half life.
These almost-stable isotopes were only able to be created in the fiery excess of energy in a neutron star collision, and are the only ones that stick around long enough to carry a fraction of that energy to the era where hairless apes could figure out that a particular black rock made of them was emitting some kind of invisible energy.
So as I said at the beginning, Uranium is significant because it stores the fossilized energy of the destroyed heart of an undead star, and we can release that energy at will if we set it up just right.
When you say it like that, is it any shock that the energy in question will melt your face off and rot your bones from the inside if you stay near it too long?
