Cosmology & the Big Bang
📋 What it is
The universe began ~13.8 billion years ago in the Big Bang and has been expanding ever since.
🗣️ Coach says
Cosmology studies the whole universe’s story. The evidence — galaxies rushing apart, a faint glow of leftover heat filling all of space — points to a hot, dense beginning ~13.8 billion years ago that has been expanding and cooling ever since. Not an explosion IN space; space itself stretching.
🧠 Memory hook
Big Bang = space itself expanding from a hot dense start, 13.8 billion years ago.
😂 Giggle
Why did the neutron star feel so dense?
Because it literally had the weight of a mountain in a teaspoon!
😲 Whoa!
You can "see" the Big Bang’s afterglow on an old untuned analog TV — a tiny fraction of that snowy static is ancient light from the early universe.
✅ Quick check: Was the Big Bang an explosion that threw matter OUT into empty space?
Say your answer out loud first — then reveal.
No — it was SPACE ITSELF expanding everywhere at once from a hot, dense state; there was no "outside" to throw things into.
The Big Bang is the expansion of space, not an explosion within pre-existing space.
🪄 Trick question: Is there a single point in the sky where the Big Bang "happened"?
Careful — think it through, then reveal.
No — it happened everywhere at once, because it was all of space expanding, not a blast from one spot.
Every point in the universe was part of the initial hot dense state.
🧪 Try it! (2 minutes)
Draw dots on a balloon and blow it up — every dot moves away from every other, like galaxies in expanding space.