How come you guys don't know or don't agree that Einstein's equation E = mc^2 come from Newton's equations?

Because it ain't true! Actually, what Einstein did was revolutionary. Obviously, you have never seen the mathematical derivation of E=mc^2. Haha.. What's the title of your book? Who's the author. I'd love to read it. Update: I beg to differ. If you like I'll derive it for you. Using the Lorentz factor, Newton's 2nd law, and little calculus. E=mc^2 has nothing to do with Newton's universal law of gravitation. It is the rest energy a body. Maybe you are confusing this with Einstein's generalization of Newton's universal law of gravity to general relativity. Update: Your book is omitting some very important details about Einstein's work. In special relativity Einstein modified Newton' s 2nd Law and generalized it to very large velocities. Gravity was not addressed in this theory. It is within the frame work of special relativity that E=mc^2 arises. In general relativity Einstein modified Newton's universal law of gravity to compliment special relativity and showed that the gravitation force is manifested by the curvature of space-time.

We don't know that or agree on that because it isn't true, and that's not how it happened or what it means. Of course, Einstein was intimately familiar with the work of Newton and other scientists before him, but Einsteins fundamental equivalence relationship between energy and rest mass is not derivable from Newton's laws of motion or gravitation.

Newton knew the speed of light?

Don't let anyone discourage you A.S. just write it all down and get into the public space and see what happens. You may have -- in fact -- come up with a way of relating them in a much easier way. I, for one, would be very happy if you did, because deriving the durn thing with the energy-momentum tensor and the Lorentz transformation is very difficult. Remember though, the key to this whole thing working -- at least as far as the rest of us have done it -- is in decoupling time from the reference frames. If you keep time constant in both frames, you will probably have a very hard time. But then again, what do I know, Relativity doesn't make any sense at all to me!