Albert Einstein was indeed a scientific genius as well as a world citizen. His contributions to the field of physics revolutionized our understanding of the universe, and his advocacy for peace and global cooperation made him a prominent figure on the world stage. Let's delve into the details of his scientific achievements and his role as a global citizen.

Einstein's Scientific Genius:
- Theory of Relativity: Einstein is best known for his theory of relativity, which consists of two major parts: the special theory of relativity and the general theory of relativity. The special theory of relativity, published in 1905, introduced revolutionary concepts such as the equivalence of mass and energy (E=mc²) and the relativity of simultaneity.
- Photoelectric Effect: In the same year, Einstein also proposed the quantum theory of light, explaining the photoelectric effect. This groundbreaking work earned him the Nobel Prize in Physics in 1921.
- Brownian Motion: Einstein's explanation of Brownian motion provided experimental evidence for the existence of atoms and molecules. His work on this phenomenon, published in 1905, further solidified the acceptance of atomic theory.
- Unified Field Theory: Throughout his life, Einstein sought to develop a unified field theory that would encompass all fundamental forces in nature. Although he did not succeed in this endeavor, his attempts paved the way for future advancements in theoretical physics.

Einstein as a World Citizen:
- Pacifism and Anti-War Activism: Einstein was a dedicated pacifist and spoke out against war. He actively campaigned for disarmament and used his influence to promote peace during times of conflict, such as World War I and II.
- Jewish and Humanitarian Causes: As a Jewish individual, Einstein was deeply concerned about the rise of anti-Semitism and the plight of Jewish people. He advocated for their rights and was involved in various humanitarian efforts, including assisting refugees and supporting civil rights.
- Global Cooperation: Einstein believed in the importance of international cooperation and unity. He was a proponent of the League of Nations, the precursor to the United Nations, and later became an advocate for the establishment of a world government to prevent future wars.
- Nuclear Weapons and the Bomb: Einstein's most well-known political involvement was his letter to President Franklin D. Roosevelt, urging the United States to develop an atomic bomb to counter the Nazi threat during World War II. However, he later regretted this decision and became an advocate for nuclear disarmament.

In conclusion, Albert Einstein's scientific genius and contributions to our understanding of the universe are unparalleled. His work on the theory of relativity and other groundbreaking theories has had a profound impact on the field of physics. Additionally, his role as a world citizen, advocating for peace, global cooperation, and humanitarian causes, further solidifies his legacy as a remarkable individual.