Why do we still do chemistry?

When quantum mechanics emerged in the early 20th century, many believed it meant that nothing more than physics was now needed to understand chemical phenomena. As Paul Dirac put it: ‘The underlying physical laws necessary for the mathematical theory of … the whole of chemistry are thus completely known.’

In philosophy, this idea was expressed with the notion of reduction, in which the more fundamental science deduces the statements of the special sciences (including chemistry). Reduction was taken to imply that one day we will not need chemistry in order to explain chemical phenomena: chemistry would be eliminated as a means of understanding the world.

Quantum mechanics has certainly affected chemistry in tangible ways. Perhaps most notably in the way its postulations about the wave-like manner of entities, the quantisation of energy levels and the concept of spin have been incorporated into chemistry’s image of the atom. In addition, a new field has emerged– quantum chemistry – that employs quantum models to predict and explain chemical phenomena.

Nevertheless, quantum chemistry has not yet substituted or eliminated other branches of chemistry. If anything, chemistry as a whole continues to prove its unique worth, producing a valuable body of knowledge with important implications for biology, drug design, even neuropsychology. So why has that prediction not come to pass – why do we still do chemistry?