1. Quantum Theory Emerges:
* Planck's Quantum Hypothesis: Max Planck proposed the revolutionary idea that energy is not continuous but quantized, meaning it can only exist in discrete packets called quanta. This was to explain the blackbody radiation spectrum, a problem that classical physics couldn't solve.
* Rise of Quantum Mechanics: Planck's hypothesis laid the foundation for quantum mechanics, which would later be developed by physicists like Niels Bohr, Werner Heisenberg, and Erwin Schrödinger.
2. Special Relativity Revolutionizes Space and Time:
* Einstein's Theory of Special Relativity: Albert Einstein published his theory of special relativity, which revolutionized our understanding of space, time, and gravity. It introduced concepts like time dilation, length contraction, and the equivalence of mass and energy (E=mc²).
3. Understanding the Nature of Light:
* Wave-Particle Duality: The debate over the nature of light – whether it was a wave or a particle – intensified. Experiments like the photoelectric effect (explained by Einstein) provided evidence for the particle nature of light, while other phenomena like interference and diffraction demonstrated its wave nature. This duality led to the idea of wave-particle duality, a fundamental concept in quantum mechanics.
4. Radioactivity Unveiled:
* Discovery of Radioactivity: Marie and Pierre Curie continued their groundbreaking research on radioactivity, discovering new radioactive elements like radium and polonium. This discovery led to the realization that atoms are not indivisible and opened doors to understanding the structure of the atom and nuclear physics.
5. Other Significant Developments:
* X-ray Diffraction: Max von Laue discovered that X-rays could be diffracted by crystals, which later became a powerful tool for studying the structure of matter.
* Discovery of the Electron: J.J. Thomson had already discovered the electron in 1897, but its properties and role in the atom were still being investigated.
The year 1900 marked the beginning of a paradigm shift in physics, moving away from the classical framework to a new understanding of the universe at the atomic and subatomic level. The developments of this era paved the way for the rapid advancements in quantum mechanics, nuclear physics, and cosmology that would shape the 20th century.
