Feynman Lectures On Gravitation -

: He posits the existence of a massless particle with spin 2 and derives the consistency requirements that lead directly to the non-linear Einstein field equations.

The 16 lectures cover a wide range of advanced theoretical physics, including: Feynman Lectures on Gravitation

Because these were postgraduate lectures given in the afternoons (while the more famous undergraduate Lectures on Physics were given in the mornings), they require a high level of mathematical maturity. Feynman Lectures on Gravitation - IOPscience : He posits the existence of a massless

: Early attempts and challenges in unifying gravity with quantum mechanics, highlighting the fundamental difficulties of low-energy quantum gravitational field theories. Study Guide Recommendations Feynman Lectures on Gravitation