The present paradigm of the whole science has been based upon the Einstein's understanding of Nature. His Special and the General Theory of Relativity have been constructed with the assumption resulting from the most famous equation ever formulated in science: energy E equals mass m times speed of light c squared,

^{2}.

Since then the speed of light has been always considered as a „constant of Nature“. However, assuming that, also the squared speed of light is nothing more than a numerical factor, what means that the Einstein's equation, E = mc^{2}, can be read in a unique way, namely that mass is equivalent to energy (just with some numerical factor c^{2}). But this conclusion is false. **Mass is not equivalent to energy**. Moreover, we still do not understand what mass really is. The nuclear reactors accidents are the most convincing proofs of this misunderstanding. We cannot control the nuclear energy as long as we misunderstand the Einstein's equation.

As I have already written yesterday, it is much better to replace the physical quantity c^{2} with one of its equivalencies (delivered to us by the Unified Family of all physical quantities including the basic and the equivalent quantities), heat flow G, or radiation intensity S, rewriting the Einstein's equation into:

E = mG, or E = mS,

and read it correspondingly: energy equals mass times heat flow, or energy equals mass times radiation intensity. If we rearrange our energy technologies according to these equations, we will surely construct more safe and economical energy deliverers.

I would begin the new study with the universal definition of mass:

**delta**x

**f**x

**m**=

**1**;

which means that the change of mass in space (delta means also Laplace operator) and time (f means also the time derivative) equals always the universal unity; an equation valid for any quantum of matter, under any conditions.