fact...

• For over a thousand years, the four books Aristotle wrote on physics provided the foundation for natural sciences in the western world
• The 'Principia' shattered Aristotelian orthodoxy by abolishing the distinction between heaven and earth.
• For the first time, there were universal principles. An apple falling on earth and the planets orbiting around the sun were now subject to the same laws.
• Space-time distances between events are well defined but time intervals or spatial distances between them depend on the state of motion of the observer.
• Space-time is not an inert entity. It acts on matter and can be acted upon.
• Einstein was led to regard gravity not as a force but a manifestation of space-time geometry.
• Our own galaxy, the milky way, has a black hole of about 3.2 million solar masses at its center.
• General relativity is widely regarded as the most sublime of all scientific creations.