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For seven years, first at the University of Chicago and then at the California Institute of Technology (where he moved in 1952), he worked in a sterile lab, making very precise measurements of the lead/uranium ratios in carefully selected samples of old rock.
有7年時間，先是在芝加哥大學，后在加州理工學院（他于1952年遷往那里），他在無菌實驗室里埋頭苦干，仔細選擇古老巖石的樣品，精密測定里面鉛/鈾的比例。
The problem with measuring the age of the Earth was that you needed rocks that were extremely ancient, containing lead- and uranium-bearing crystals that were about as old as the planet itself—anything much younger would obviously give you misleadingly youthful dates—but really ancient rocks are only rarely found on Earth. In the late 1940s no one altogether understood why this should be. Indeed, and rather extraordinarily, we would be well into the space age before anyone could plausibly account for where all the Earth's old rocks went. (The answer was plate tectonics, which we shall of course get to.) Patterson, meantime, was left to try to make sense of things with very limited materials. Eventually, and ingeniously, it occurred to him that he could circumvent the rock shortage by using rocks from beyond Earth. He turned to meteorites.
測定地球年齡的問題在于，你需要有極其古老的巖石，內有含鉛和鈾的晶體，其古老程度幾乎與這顆行星一樣──要是巖石年輕得多，測出的年代顯然會比較年輕，從而得出錯誤的結論，而真正古老的巖石在地球上是很難找得著的。到20世紀40年代末，誰也不知道這是什么原因。實際上，要等到太空時代，才可能有人貌似有理地說明地球上古老巖石的去向，這真是不可思議的。（答案在于板塊構造，我們當然將談到這個問題。）與此同時，彼得森只能在材料非常有限的情況下把這一切搞清楚。最后，他突然聰明地想到，他可以利用地球之外的巖石，從而繞開缺少巖石的問題。他把注意力轉向隕石。
The assumption he made—rather a large one, but correct as it turned out—was that many meteorites are essentially leftover building materials from the early days of the solar system, and thus have managed to preserve a more or less pristine interior chemistry. Measure the age of these wandering rocks and you would have the age also (near enough) of the Earth.
他提出了一個假設──一個很有遠見的假設，結果證明非常正確，即，許多隕石實際上是太陽系早期留下來的建筑材料，因此多少保留著原始的內部化學結構。測定了這些四處游蕩的巖石的年代，你也就（接近于）測定了地球的年齡。
