Americans David J. Gross, H. David Politzer and Frank Wilczeck won the 2004 Nobel Prize in physics yesterday for their work in the discovery and exploration of the force that binds particles inside an atomic nucleus.

The research has helped take science a step closer to "fulfilling a grand dream, to formulate a unified theory comprising gravity as well - a theory for everything," the Royal Swedish Academy of Sciences said in awarding the prize.

The trio - researchers at the University of California, Santa Barbara, the California Institute of Technology and the Massachusetts Institute of Technology - were cited for their important theoretical discoveries "concerning the strong force, or the ’colour force’ as it is also called," the academy said in its citation. "The strong force is the one that is dominant in the atomic nucleus, acting between the quarks inside the proton and the neutron."