Researchers have finally found a link between string field theory and quantum mechanics.

The findings could allow researchers to use string field theory (or a broader version called "M-theory") as the basis of all physics, the University of Southern California (USC) reported.

"This could solve the mystery of where quantum mechanics comes from," said Itzhak Bars, USC Dornsife College of Letters, Arts and Sciences professor and lead author of the paper.

Instead of using quantum mechanics to validate string field theory, the researchers instead used string field theory to try to validate quantum mechanics. The research team demonstrated a set of fundamental quantum mechanical principles, dubbed "commutation rules," that are taken from the geometry of strong joining and splitting.

"Our argument can be presented in bare bones in a hugely simplified mathematical structure," Bars said. "The essential ingredient is the assumption that all matter is made up of strings and that the only possible interaction is joining/splitting as specified in their version of string field theory."

For decades physicists have been looking for a way to link quantum mechanics and general relativity. String theory, which was first proposed in the 1970s, helped solve some of the inconsistencies of quantum gravity and suggested the "fundamental unit of matter was a tiny string," as opposed to a point. This suggests the only possible interactions of matter are strings joining or splitting. For the following four decades researchers have been trying to work out the ins and outs of string theory, but have not yet been able to come up with a concrete set of rules.

Researchers can use Newtonian mechanics to describe large-scale phenomena such as how gravity holds the moon in its orbit; for smaller scale scenarios, such as the interaction of subatomic particles, researchers use relativistic quantum field theory. Quantum mechanics is an "invaluable and accurate framework for understanding the interactions of matter and energy at small distances," USC reported. While it can show how things work on the small scale, but researchers are unsure of its foundational quantum commutation rules that predict uncertainty in the universe.

"The commutation rules don't have an explanation from a more fundamental perspective, but have been experimentally verified down to the smallest distances probed by the most powerful accelerators. Clearly the rules are correct, but they beg for an explanation of their origins in some physical phenomena that are even deeper," Bars said.

The findings were published Oct. 27 by the journal Physics Letters.