What is space-time made of ?

In the first part of this book, the author synthesizes the main results and formulas of physics-Albert Einstein's, with general relativity, gravitational waves involving elastic deformable space-time, quantum field theory, Heisenberg's principle, and Casimir's force implying that a vacuum is not nothingness. In the second part, based on these scientific facts, the author re-studies the fundamental equation of general relativity in a weak gravitational field by unifying it with the theory of elasticity. He considers the Ligo and Virgo interferometers as strain gauges. It follows from this approach that the gravitational constant G, Einstein's constant ?, can be expressed as a function of the physical, mechanical and elastic characteristics of space-time. He overlaps these results and in particular Young's modulus of space-time, with publications obtained by renowned scientists. By imposing to satisfy the set of universal constants G, c, ?, h and by taking into account the vacuum data, h