How did David Gross discover asymptotic freedom?
The discovery came from a first-principles calculation using the renormalization group. In 1973, I was trying to understand the strong force's behavior at high energies, where experiments at SLAC had shown that quarks behave almost freely. I realized that the beta function—which describes how the coupling constant changes with energy—could be negative for non-Abelian gauge theories. That was the key: if the coupling decreases at high energies, you get asymptotic freedom. I worked this out with Frank Wilczek, and we found that only non-Abelian gauge theories, like quantum chromodynamics, have this property. It was a beautiful idea, but we needed to check the math. The calculation was straightforward once we applied the renormalization group correctly. This result not only explained the experimental data but also established QCD as the correct theory of the strong interactions.
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