**Answer:** 1905

**Some extra relevant information:**

Einstein’s Four Annus Mirabilis, also known as his Miracle Papers, were published in the year 1905. This remarkable year marked a significant turning point in the field of physics and solidified Albert Einstein’s reputation as one of the greatest scientific minds of all time.

During this period, while working as a patent examiner at the Swiss Patent Office in Bern, Einstein made groundbreaking contributions to theoretical physics. In four separate papers, he tackled a range of topics that revolutionized our understanding of the physical world.

One of the papers focused on the photoelectric effect, which explained the behavior of light when it interacts with matter. This work laid the foundation for the development of quantum theory, and Einstein was eventually awarded the Nobel Prize in Physics in 1921 for his explanation of the photoelectric effect.

Another paper introduced the theory of special relativity, which challenged classical Newtonian physics and introduced the concept of the speed of light as a fundamental constant. This theory revolutionized our understanding of space, time, and motion, and paved the way for the development of Einstein’s theory of general relativity.

The third paper delved into the phenomenon of Brownian motion, providing a mathematical explanation for the random movement of particles in a fluid. This work provided further evidence for the existence of atoms and molecules, which were still subjects of debate at the time.

Lastly, Einstein’s fourth paper proposed the famous equation E=mcÂ˛, which showed the equivalence of mass and energy. This equation, now widely known and recognized, forms the basis for atomic energy and our understanding of nuclear reactions.

Together, these papers published in 1905 not only established Einstein as a remarkable physicist but also fundamentally transformed our understanding of the physical world. Their impact continues to reverberate in modern physics, inspiring further research and technological advancements.

In conclusion, Einstein published his four Annus Mirabilis (“Miracle Papers”) in the year 1905. This pivotal moment in scientific history marked a turning point in our understanding of the universe and solidified Einstein’s legacy as one of the most brilliant minds to have ever graced the field of physics.