Books like Stewart's or Thomas's calculus can provide a solid foundation in calculus and are commonly used in introductory calculus courses. They cover the essential topics and techniques needed for many areas of science and engineering, including theoretical physics.
However, if you wish to delve deeper into theoretical physics and gain a more rigorous understanding of calculus, books like Spivak's "Calculus" or Apostol's "Calculus" can be beneficial. These books are known for their mathematical rigor and provide a more comprehensive treatment of calculus. They delve into the theoretical aspects of the subject, including proofs and advanced concepts, which can be particularly useful for those interested in theoretical physics.
In theoretical physics, a strong mathematical foundation is crucial, and understanding calculus at a deeper level can be advantageous when dealing with complex physical theories and mathematical models. Books like Spivak's or Apostol's can help you develop a more rigorous and abstract understanding of calculus, which can aid in tackling advanced topics in theoretical physics, such as quantum mechanics, general relativity, or quantum field theory.
Ultimately, the choice of books depends on your level of mathematical aptitude, your goals, and the depth of understanding you seek. If you feel comfortable with the level of rigor provided by books like Stewart's or Thomas's calculus, you can certainly begin studying theoretical physics. However, if you want to explore the mathematical foundations in greater detail, books like Spivak's or Apostol's can be valuable resources. It's also worth noting that alongside calculus, studying other branches of mathematics, such as linear algebra, differential equations, and mathematical methods, will further enhance your understanding of theoretical physics.