Much of the physics world, and millions in funding, is spent on the ceaseless hunt for a theory of everything which unites general relativity and quantum mechanics. Quantum gravity – a description of gravity that obeys the principles of quantum mechanics – is held up as the holy grail that will lead our discovery, however Isaac Layton argues this search is misguided.

In 1905, whilst working in a patent office, Albert Einstein published four ground-breaking papers, setting the stage for half a century of rapid progress in theoretical physics.

Two of the papers laid the basis for what is now known as general relativity. Completed a decade later in 1915, general relativity provided a new understanding of gravity, explaining the apparent force we feel from massive objects in terms of the bending of space and time. To this day, general relativity provides our best theory of gravity, and has been extensively tested, most recently with the detections of gravitational waves.

Although general relativity provided a radical conceptual shift from the earlier work of Newton, it is still what physicists would call a classical theory. Classical theories are those which build on the basic intuitions that we all have about the natural world: that objects have definite positions in space, and that these don’t change when we look at them.