The nineteenth-century physicist William Thomson, later known as Lord Kelvin, made his own brilliant blunder when he calculated that the Earth was less than 100 million years old – about fifty times younger than the age deduced from modern radiometric measurements. Though Kelvin’s estimate was seriously flawed, the effort remains central to the history of knowledge, because it applied real science – the laws of physics – to what had long been a subject of vague speculation.
十九世纪物理学家威廉·汤姆孙（William Thomson），即后来的开尔文勋爵（Lord Kelvin）也犯过杰出的错误——他测算地球的寿命不超过1亿年——比用现代辐射测量测定的年龄年轻五十倍。尽管开尔文的估算出现了严重的错误，但他的努力仍在知识史中占有中心地位，因为他将真正的科学——物理学定律——应用于长期以来只靠模糊猜测的问题。