The New Background of Science by Sir James Jeans is an insightful exploration of the profound changes in twentieth-century physics and their philosophical implications. Sir James Jeans delves into the transformative concepts of relativity and quantum theory, highlighting how these have reshaped our understanding of the physical world. He provides a clear and accessible account of complex scientific principles, such as space and time, the nature of matter and radiation, wave mechanics, and the principle of indeterminacy. The book contrasts twentieth-century physics with the deterministic and materialistic views that dominated the nineteenth century, offering a more nuanced perspective that aligns better with everyday human experience. Through a blend of science and rudimentary philosophy, Jeans invites readers to appreciate the broader significance of scientific discoveries, making the content valuable for both students of physics and general readers interested in modern science.