Physics

Resources

• Taking Census of Physics (opens new window)
• Simulation-based high school physics course notes (opens new window)
• Intuitive Guide to Maxwell's Equations https://hn.premii.com/#/comments/23700295 (opens new window)

Basic/Interesting question to solve:

The diameter of earth is 12,756 km. Now that we know that:

• What is the circumference of Earth at the equator?
• What is the circumference of Earth at the 42nd latitude?
• What's the volume of earth?
• What's the surface area?
• A plane travels at 900km per hour
  • how long does it take to fly from top to bottom?
  • It flies at 12.7km from the surface. How long now?
  • It has acceleration of 1 m/s^2. How long now?
• Calculate the volume of each:
  • 0–35km Crust
  • 35–2,890km Mantle
  • 2,890–5,150km Outer core
  • 5,150–6,360km Inner core

Gravity

• How much gravitational force does the moon have on the earth?
• How much does the sun have?
• What are the tides different? Earth friction? Positioning of moon + sun? Natural dissonance of tides compounding?

Relativity

• I am standing at a clock tower (hint: twin paradox)
  • I travel for 1 hour at the speed of light away from the clock. I look at my watch. What is the time on my watch? I look at the clock. What is the time on the clock?
  • I travel for 1 hour at the speed of light back to the clock. I look at my watch. What is the time on my watch? I look at the clock. What is the time on the clock?

Interesting concepts

Boltzman brain

A Boltzmann brain is an idea in science. Imagine the universe is so big and so old that, eventually, a brain pops into existence all by itself. It’s just random particles coming together in the right way, by pure chance. This brain thinks and feels like we do but doesn’t come from a living being. It doesn't even need to be a physical brain - it could just think it's a physical brain.

It's a nice thought experiment for you, the reader. Imagine that the reality you perceive, including the past you remember, is nothing more than a fleeting momentary construct. As you read this, you think that you are a human, with a past and a future. But what if these "memories" and this "sense of self" is simply a random event that makes you feel like you are a long-living entity. Consider that in the next moment, your entire existence might dissolve into the randomness from which it emerged.