The physicist known for his theory of relativity is Albert Einstein. His revolutionary theories, published in the early 20th century, fundamentally changed the understanding of time, space, and energy. The equations of relativity highlighted the interconnectivity of the universe and introduced concepts such as time dilation and the mass-energy equivalence principle, famously encapsulated in the equation E=mc². Einstein's contributions extend beyond theoretical physics; he became a public intellectual and humanitarian, advocating for civil rights and peace. His legacy lives on as one of the most celebrated scientists in history, symbolizing the profound impact of innovative thought and inquiry.