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1 一次精彩的估算 1945年7月,当世界上第一颗原子弹试验爆炸时,作为参与研究的主要科学家们,极关心此次爆炸的威力如何。据传,在场的费米从袋里掏出一把碎纸片撒向空中,气浪把纸片吹出好几米远,费米测量了纸片吹开的水平距离,经过估算,就讲出这颗原子弹的爆炸威力相当于两万吨TNT炸药爆炸的威力。这使在场的科学家有的大为惊讶,有的费解,有的怀疑。事后证实,费米的估算与各种精密仪器测算的结果非常接近。其实,费米所用的估算方法是根据“平抛——风力——威力”关系算出的。这是一次精彩的估算。
1 A wonderful estimate In July 1945, when the world’s first atomic bomb exploded, the main scientists involved in the study were extremely concerned about the power of the explosion. According to reports, Fermi, who was present at the scene, took out a piece of shredded paper from the bag and scattered it into the air. The air wave blew the paper a few meters away. Fermi measured the horizontal distance the paper was blown open. After an estimate, he spoke it out. The explosive power of the atomic bomb is equivalent to the explosiveness of 20,000 tons of TNT explosives. This made some of the scientists present surprised, some puzzling, some doubts. It was confirmed afterwards that Fermi’s estimate was very close to the results of various precision instruments. In fact, Fermi’s estimation method is based on the “flat throw - wind - power” relationship. This is a wonderful estimate.