I'm taking a course in general relativity, it's a beautiful theory and I personally have no reason to doubt it's validity. However, I also recently stumbled upon and alternative theory of gravitation which was worked out by Oleg Jefimenko and is published in the following book: https://www.amazon.com/Gravitation-...-Conclusion/dp/091740615X/ref=ntt_at_ep_dpt_4 I'm off campus and don't have access to journals for the weekend, but I'm wondering if anyone knows anything about this work? The following excerpt from the review has me intensely curious about the idea: It seems what Jefimenko has done is to make Newtonian gravity consistent with the principle of causality, and in the process introduced a "new" (not new in general relativity, but I believe new in the context of Newtonian gravity) gravimagnetic field. I'm considering buying this book and reading it for myself, but I'd like to find out a little more first. For a start, I'd be very very curious if his theory predicts gravitational lensing and gravitational time dilation - both well observed phenomena which it seems any theory of gravity should contain, and which seem fundamental to the idea of a curved space time, I think it'd be a very big deal if you could create these effects without invoking a metric theory.