Galaxy & Stars
Gravity pulled matter together to form galaxies, stars, and the elements that make life possible.
From Gas to Galaxies
After the Big Bang, the universe was mostly hydrogen gas. Gravity slowly pulled denser regions together, forming the first stars about 200 million years later. These first-generation stars were massive and short-lived.
Stars clustered into galaxies. Our Milky Way alone contains 100–400 billion stars. The observable universe has around 2 trillion galaxies.
Stellar Nucleosynthesis
Stars are nature's element factories. In their cores, nuclear fusion converts hydrogen into helium, then into carbon, oxygen, silicon, and iron. When massive stars explode as supernovae, they scatter these elements across space — and create even heavier elements like gold and uranium.
- •Stars create elements through nuclear fusion
- •Supernovae distribute elements across the cosmos
- •These elements eventually form planets, water, and life
The Economics Connection
The periodic table is essentially an inventory of cosmic production. Gold is rare because it requires a neutron star collision. Iron is abundant because it's the most stable fusion product. Scarcity — the core concept of economics — is literally written into physics.
💡 Did You Know?
Gold is so rare because it can only be produced when two neutron stars collide — an event that happens only a few times per million years in our galaxy.