Nuclear Physics and Radioactivity
Radioactivity is spontaneous and random. The probability that an atom will decay remains constant for the entire life of the atom. If you think about it, this is really strange. How can it not matter whether a uranium atom is 1 million years old or 1 billion years old? Surely the billion year old atom would seem more likely to decay in the near future?
On the other hand, it would also be pretty weird if we were able to distinguish young atoms from old ones, and we would be able to do that if the probability of decay increased with age. But still, what mechanism could be at work inside that atom that would be immune to the passage of time, so that the decay event would remain completely unpredictable?
The answer is tied to the uncertainty principle. The protons and neutrons have wavelike characteristics, which means that their positions and their energy levels are not precisely defined. This allows the particles to remain in a bound up state while still having a probability of becoming unbound. The particles are constantly jiggling and there’s a fixed probability over time that the jiggling will bounce a particle all the way out of the nucleus.
Khan Academy Videos about exponential decay
My spreadsheet showing simplified mathematics of radioactive decay
Nuclear Fission simulated with ping-pong balls and mousetraps
Nuclear Fission simulator
Alpha decay simulation
Periodic Table with all isotopes
Veritasium videos about radiation
How Damaging is Radiation?
Radiation vs Radioactive Particles :
How to calculate binding energy: