classical mechanics was able to establish successfully the
conservation of mass as a law of independent validity.

Let me add a final remark of a fundamental nature. The success of the
Faraday-Maxwell interpretation of electromagnetic action at a distance
resulted in physicists becoming convinced that there are no such
things as instantaneous actions at a distance (not involving an
intermediary medium) of the type of Newton's law of gravitation.
According to the theory of relativity, action at a distance with the
velocity of light always takes the place of instantaneous action at a
distance or of action at a distance with an infinite velocity of
transmission. This is connected with the fact that the velocity c
plays a fundamental role in this theory. In Part II we shall see in
what way this result becomes modified in the general theory of
relativity.


Notes

*) E[0] is the energy taken up, as judged from a co-ordinate system
moving with the body.

**) As judged from a co-ordinate system moving with the body.

***[Note] The equation E = mc^2 has been thoroughly proved time and
again since this time.



EXPERIENCE AND THE SPECIAL THEORY OF RELATIVITY