In the famous “Epigram on Sir Isaac Newton”, the poet Alexander Pope wrote:
Nature and nature’s laws lay hid in night:
God said, Let Newton be! and all was light.
In reply to this, J. C. Squire (1884-1958) continued:
It did not last: the Devil howling “Ho!
Let Einstein be!” restored the status quo.
In the twentieth century, the picture of our world has changed entirely. In the past, the notions of space and time were accurate and robust, allowing a proper and robust cognitive organisation of object. The evidence of space-time order would enable us to set a causal structure that regulates the external world. Scientists were looking for a simple and strong theory to explain the regularity of the world, whereas this world would have to conform to the mathematical language.
New description of the world
Then, when Einstein’s relativity and quantum theory had appeared in the scientific panorama, the assumptions of classical physics, perfectly intuitive and in accord with the most common perception of the world, were deconstructed one by one.
Some strange things happen in this new description of the world. There is no precise measure of time and space: a quantum object has no defined properties (we can only detect an electron in a specific volume of space, regardless of the instrument we use).
There is no objectivity about the experiment: an experiment on a quantum object is always altered by the observer. There is no static universe: our universe is, according to Hubble, constantly expanding. Stop reading for a moment and imagine something that is constantly expanding. We are living in such space!
Moreover, there are fewer practical experiments and more mental experiments to provide conclusions about the world. Einstein used abstract examples to develop both special relativity theory and general relativity. Schrödinger developed his famous example of the cat to illustrate quantum mechanics theory.