The Universe is expanding gradually now. But its initial expansion was almost impossibly rapid as it likely grew from quantum scale fluctuations in a trillionth of a second. In fact, this cosmological scenario, known as Inflation, is now reported to be further quantified by an analysis of three years of data from the WMAP spacecraft.

On the frozen tundra near the bottom of our world, increasingly sophisticated instruments listen for a more precise echo of how our universe started. Sunday, independent collaborations behind three such instruments announced evidence that...