Throughout history, several scientists have profoundly changed our understanding of the universe.

1. **Isaac Newton (1643-1727)**

Newton’s laws of motion and universal gravitation laid the groundwork for classical mechanics.

• Developed calculus.
• Introduced the concept of gravity.
• Published “Philosophiæ Naturalis Principia Mathematica” in 1687.

2. **Albert Einstein (1879-1955)**

Einstein’s theories of relativity revolutionized our perspective on space, time, and gravity.

• Special Theory of Relativity (1905).
• General Theory of Relativity (1915).
• E=mc² equation demonstrates the equivalence of mass and energy.

3. **Galileo Galilei (1564-1642)**

Galileo’s improvements to the telescope and his observational astronomy challenged the geocentric model.

• Discovered the four largest moons of Jupiter.
• Supported heliocentrism.
• Studied the phases of Venus.

4. **Stephen Hawking (1942-2018)**

Hawking’s work on black holes and cosmology has deeply influenced modern astrophysics.

• Formulated theories on black hole radiation.
• Contributed to the understanding of the Big Bang theory.
• Authored “A Brief History of Time”.

5. **Niels Bohr (1885-1962)**

Bohr’s contributions to quantum mechanics transformed theories about atomic structure and behavior.

• Developed the Bohr model of the atom.
• Won the Nobel Prize in Physics (1922).
• Co-founded the Copenhagen interpretation of quantum mechanics.

6. **Carl Sagan (1934-1996)**

Sagan popularized science, especially astronomy, through various media, inspiring a generation.

• Hosted the TV series “Cosmos”.
• Promoted the search for extraterrestrial life.
• Wrote numerous popular science books.

7. **Edwin Hubble (1889-1953)**

Hubble’s discoveries established the field of extragalactic astronomy and led to the understanding of the expanding universe.

• Observed that galaxies are moving away from us.
• Formulated Hubble’s Law.
• Discovered the existence of other galaxies beyond the Milky Way.

**Comparison of Contributions**

**Mind Map**

1. Newton – Gravity, Calculus, Classical Mechanics

2. Einstein – Space-Time, Relativity, Energy-Mass

3. Galileo – Telescope, Heliocentrism, Astronomy

4. Hawking – Black Holes, Cosmology, Popular Science

5. Bohr – Quantum Physics, Atomic Models

6. Sagan – Public Understanding, Extraterrestrial Life

7. Hubble – Galaxy Observations, Universe Expansion

**Conclusion**

These scientists have transformed our understanding of the universe, providing insights that have lasting impacts and continue to inspire future generations in scientific exploration.