Lecture Notes: How Many Things Are There?

Introduction

• Speaker: Michael from Vsauce
• Central question: How many things are there in the universe?

Human Perspective

• If every human (7.159 billion) was thrown into the Grand Canyon, they wouldn't fill it.
• Humans produce 1-2 liters of spit daily; not enough to fill an Olympic swimming pool in a lifetime.

Counting "Things"

• Definition of a "thing": Anything you can think about or talk about.
• "Things" can be:
  • Real
  • Imaginary
  • Abstract
  • Ideas
• Example: Making a video about counting things is itself a "thing".

Physical Things vs. Imaginary Things

• Counting Physical Things:
  • The observable universe: 62 billion light-years in any direction.
  • Approximately 10^80 elementary particles in the observable universe.
  • Every physical object (like water, dogs, planets) is just a name for arrangements of these particles.
• Future Discoveries:
  • If elementary particles are made of smaller things, we may need to count those too.
  • Planck volume: 10^183 things could fit in the observable universe.

Thoughts and Imagination

• Number of Possible Thoughts: Infinite possibilities (e.g., numbers).
• Unthought thoughts don’t exist until thought of.
• Limitations on thinking arise from the size and energy of the observable universe.

Energy and Time Limitations

• Universe will run out of usable energy in 1 trillion to 100 trillion years.
• When energy is exhausted, no further thoughts can be generated.

Maximum Number of Thoughts Calculation

• Total mass of the universe can be imagined as human brains thinking:
  • Hypothetical machine could compute at 1.36 × 10^50 bits/sec.
  • Mass of the observable universe: 3.4 × 10^60 kg.
  • Total processing capacity: 4.624 × 10^110 bits/sec.
• Time until heat death: 3.154 × 10^116 seconds.
• Average thought = 800 bits.
• Total possible thoughts = 1.458 × 10^227.

Conclusion

• Number of thoughts exceeds the number of physical things in the universe.
• Final Thought: In the grand scheme, it’s the thought that counts.
• Thanks for watching.