Who do you think is the greatest scientist of the 20th century?

There were many great scientists in the 20th century, making it difficult to determine who is the greatest. However, if I had to choose one as the greatest scientist of the 20th century, I would nominate Albert Einstein.

Albert Einstein’s contributions greatly transformed the landscape of modern science. Here are his major achievements in key areas:

1：Special Relativity (1905)

Einstein proposed the theory of Special Relativity in his paper "On the Electrodynamics of Moving Bodies." This theory is based on two main postulates:

The laws of physics are the same in all inertial reference frames.
The speed of light in a vacuum is constant for all observers, regardless of the motion of the light source.
The core formula of Special Relativity is the famous E=mc , which indicates that mass and energy are equivalent. This formula revealed that small amounts of mass can be converted into a large amount of energy, laying the theoretical groundwork for nuclear energy development.

2：General Relativity (1915)

General Relativity extended Special Relativity to include acceleration and gravity. In his paper "The Field Equations of Gravitation," Einstein introduced a geometric description of the gravitational field—curvature of spacetime—rather than the traditional concept of force. General Relativity successfully explained phenomena such as the precession of Mercury’s orbit and predicted the existence of black holes and gravitational waves (the latter of which were directly detected in 2015).

3：Photoelectric Effect (1905)

In a paper published concurrently with Special Relativity, Einstein explained the photoelectric effect—where light striking a metal surface releases electrons. He introduced the concept of photons and used quantum theory to explain the photoelectric effect. This work earned him the Nobel Prize in Physics in 1921 and laid an important foundation for the development of quantum theory.

4：Brownian Motion and Molecular Kinetic Theory (1905)

Einstein also supported the existence of molecular kinetic theory through his theoretical explanation of Brownian motion. This theory provided experimental evidence for the existence of molecules and atoms, further advancing the field of statistical physics.

5：Einstein-Podolsky-Rosen Paradox (1935)

In 1935, Einstein, along with his colleagues Podolsky and Rosen, proposed the EPR Paradox, which questioned the completeness of quantum mechanics. Although the paradox was originally intended to propose the "hidden variables" theory in quantum mechanics, it also spurred the development of quantum entanglement and quantum information science.

6：Public Affairs and Philosophy

Einstein was not only a scientist but also a social activist. He had profound views on peace, education, and social justice. He actively participated in anti-war movements, advocated for scientific education, and expressed concerns about the cultural and political status of the Jewish people.

In summary, Einstein’s scientific achievements significantly advanced the field of physics, and his ideas have had a profound impact on many areas of modern science. He was not only a scientist but also a thinker who deeply influenced human thought and culture.

So, who do you think is the greatest scientist of the 20th century?