Gravity: History and Discoveries

Introduction to Gravity

• Gravity is a force that pulls things towards the earth.
• Considered a fascinating mystery that many scientists have investigated.

Ancient Theories on the Falling of Bodies

• Aristotle: Believed that heavier bodies fell faster.
• Galileo Galilei: Disproved Aristotle by demonstrating that the falling of bodies does not depend on their weight.
  • Experiments from the Tower of Pisa.
  • Inclined plane and bells to study falling.
  • Introduction of the concept of acceleration.

Isaac Newton and Universal Gravitation

• Newton: Formulated the law of universal gravitation.
  • Introduction of calculus.
  • Legend of the falling apple.
  • Newton’s "Cannon" thought experiment.
  • Discovered that gravity acts at a distance, like between Earth and the Moon.
  • Problems with Newton's theory: Anomalies like the precession of Mercury's perihelion.

Albert Einstein and Relativity

• Einstein: Reformed physics with the theory of relativity.
  • Principle of equivalence between acceleration and gravity.
  • General Relativity: Gravity is a curvature of spacetime.
  • Mass curves spacetime and planets follow these curves.
  • Confirmation of Einstein’s theory through experiments like Eddington’s in 1919.

Modern Concepts of Gravity

• Einstein's relativity is still confirmed by modern experiments.
• Discovery of gravitational waves.
• Gravity remains an enigmatic force, not yet quantized.
  • Current challenges: Reconciliation with quantum mechanics.
  • Ongoing research: String theory and loop gravity.

Conclusion

• Gravity continues to be a fascinating and complex field of study.
• Importance of learning and further exploring the subject.