Michael Duff (physicist)

“Theoretical physicists like to ask the big questions: How did the Universe begin? What are its fundamental constituents? What are the laws of nature that govern these constituents?The smallest constituents of matter are, by definition, the {{W|elementary particle}}s. But what is an elementary particle, exactly? How do we know when we have reached the bottom line? Well, it turns out to be easier to say what an elementary particle is not.”

“Superunification underwent a major paradigm shift in 1984 when eleven-dimensional supergravity was knocked off its pedestal by ten-dimensional superstrings. This last year has witnessed a new shift of equal proportions: perturbative ten-dimensional superstrings have in their turn been superseded by a new non-perturbative theory called {{W|M-theory}}, which describes supermembranes and superfivebranes, which subsumes all five consistent string theories and whose low energy limit is, ironically, eleven-dimensional supergravity.”

“On compactification to six spacetime dimensions, the fundamental heterotic string admits as a {{W|soliton}} a dual string whose effective worldsheet action couples to the background fields of the dual formulation of six-dimensional supergravity.”

“In 1973 two {{W|Abdus Salam|Salam}} protégés (Derek Capper and the author) discovered that the conformal invariance under Weyl rescalings of the metric tensor gμν(x → Ω2(x) gμν(x) displayed by classical massless field systems in interaction with gravity no longer survives in the quantum theory. Since then these {{W|Weyl anomaly|Weyl anomalies}} have found a variety of applications in black hole physics, cosmology, string theory and statistical mechanics.”