A guy was walking along the street one night, when he came upon a man一a theoretical¹ physicist一on his hands and knees under a streetlight, searching the street. The fellow asked him what he was looking for, and the theoretician replied, "I' m looking for my car keys.” Being a helpful sort, the fellow started searching, too. After a time he asked, "Are you sure you lost them here?"

一天晚上，一个小伙子在街上漫步时遇到了一个理论物理学家。只见他正爬在路灯下，像是在寻找什么东西。小伙子问他在找什么。那个理论家回答:“我在找我的车钥匙。”出于好心，小伙子也开始帮着他找钥匙。过了一会儿，小伙子问:“你确定钥匙丢在这里了吗?”

"Of course not,” replied the theoretician. "But at least there's light here.”

“当然不是了，”理论家答道，“但是至少这儿有光亮。”