In discussions about the Scientific Revolution, a key expression is “modern science”. Its traditional understanding – mathematization and experimentation – is too weak: Euclid’s geometry and Archimedes’ physics were both perfectly mathematical and were based on objective experience. And it is too strong: in natural sciences beyond physics, math is quite limited. Joseph Needham in his Grand Question actually focused on modern physics originating with Galileo. To make this question really historical, it is narrowed down to physics and expanded in (...) cultural time and space: Which feature of modern physics, absent in Greco-Roman and Medieval sciences, prevented the next major advance after Archimedes, and prevented non-Europeans to join modern science for centuries after Galileo and up to the 20th century? In modern physics, besides the tools of mathematics and experiment, no less important is the third tool, described by Einstein as "the boldest speculation [to] bridge the gaps between the empirical data." This tool implies belief in the hidden fundamental laws of the universe and the right to invent fundamental concepts that are not directly observable, but can be tested experimentally along with the theory based on them. Such a belief, or the postulate of modern science, is the key distinction of modern physics. Among the great modern physicists there were eight theorists who successfully invented new fundamental concepts. And each of these inventions led to breakthrough advances of modern physics. (shrink)