"We are all in orbit around the center of the Milky Way galaxy. How big is this collection of stars? Somewhere between 200 and 400 billion suns in the Milky Way galaxy, about 100,000 light years across."
How do we measure the universe, and are we doing it wrong? Physicist Brian Cox uncovers the hidden assumptions behind our units of measurement, showing how human perspective distorts our understanding of space, time, and scale.
Cox explores the fundamental constants—like the speed of light, Planck’s constant, and gravity—that underpin the very fabric of our universe.
00:00 Biologically-based measurements
01:26 3 fundamental quantities
01:42 The speed of light
01:57 Strength of gravity
02:26 Planck’s constant
04:20 Observing a Planck length
05:32 Distance to the planets
08:18 Distance to other galaxies
### **Key Takeaways**
1. **Human Scales Are Arbitrary** – Meters and feet are based on biology, not universal truths. Aliens wouldn’t use them.
2. **Nature’s Fundamental Constants** – Physics reveals deeper rulers:
- **Speed of light** (cosmic speed limit).
- **Planck’s constant** (quantum uncertainty).
- **Gravity’s strength** (shapes spacetime).
3. **Planck Length: The Smallest Possible** – At **10⁻³⁵ meters**, probing further creates black holes. A proton vs. This is like the solar system vs. A virus.
4. **Cosmic Scales Defy Intuition** – From our Sun (flying around it takes a year) to galaxies (Andromeda’s light is 2.5M years old), the universe is **inconceivably vast**—possibly infinite.
5. **Life’s Potential Cosmic Role** – If intelligence persists, it could someday manipulate galaxies, making life *more* than a "speck."
### **Mind-Blowing Fact**
The edge of the *observable* universe is **46B light-years away**—but the *actual* universe may be infinite.
*(Host: Brian Cox | Particle Physicist)*
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