Cosmology & the Universe
📋 What it is
The expanding universe contains dark matter and dark energy — unseen ingredients that dominate the cosmos.
🗣️ Coach says
The deeper cosmic picture is strange: ordinary matter (stars, planets, us) is only about 5% of the universe. The rest is invisible "dark matter" that holds galaxies together with extra gravity, and "dark energy" that is speeding the universe’s expansion up. We infer both from their effects.
🧠 Memory hook
Ordinary stuff ≈ 5%. Dark matter (extra gravity) + dark energy (speeding expansion) = the rest.
😂 Giggle
What did the asteroid say to the other asteroid?
"I'm having an impact on your life whether you like it or not!"
😲 Whoa!
Everything humans have ever seen — every star, planet and galaxy — is only about 5% of the universe; the other 95% is dark matter and dark energy we can’t directly see.
✅ Quick check: If we can’t see dark matter, how do we know it’s there?
Say your answer out loud first — then reveal.
By its gravity — galaxies spin and cluster as if far more mass is present than the visible stars provide.
Dark matter is inferred from gravitational effects, not direct light.
🧪 Try it! (2 minutes)
Spin a coin on a table too slowly and it wobbles off; galaxies spin "too fast" to hold together with visible matter alone — extra gravity (dark matter) holds them.