The theory of quantum mechanics has transformed daily life since being proposed a century ago, yet how it works remains a mystery — and physicists are deeply divided about what is actually going on, a survey in the journal Nature said Wednesday.

“Shut up and calculate!” is a famous quote in quantum physics that illustrates the frustration of scientists struggling to unravel one of the world’s great paradoxes.

For the last century, equations based on quantum mechanics have consistently and accurately described the behavior of extremely small objects.

However, no one knows what is happening in the physical reality behind the mathematics.

The problem started at the turn of the 20th century, when scientists realised that the classical principles of physics did not apply to things on the level on atoms.

Bafflingly, photons and electrons appear to behave like both particles and waves. They can also be in different positions simultaneously — and have different speeds or levels of energy.

In 1925, Austrian physicist Erwin Schroedinger and Germany’s Werner Heisenberg developed a set of complex mathematical tools that describe quantum mechanics using probabilities.

This “wave function” made it possible to predict the results of measurements of a particle.

These equations led to the development of a huge amount of modern technology, including lasers, LED lights, MRI scanners and the transistors used in computers and phones.

But the question remained: what exactly is happening in the world beyond the maths?

To mark the 100th year of quantum mechanics, many of the world’s leading physicists gathered last month on the German island of Heligoland, where Heisenberg wrote his famous equation.

More than 1,100 of them responded to a survey conducted by the leading scientific journal Nature.