Eureka

Eureka is an interjection used to celebrate a discovery, a transliteration of a word attributed to Archimedes. The word comes from Ancient Greek εὕρηκα heúrēka "I have found (it)", which is the 1st person singular perfect indicative active of the verbheuriskō "I find".  The reconstructed Ancient Greek pronunciation is [heúrɛːka], while the Modern Greek pronunciation is [ˈevrika].

The accent of the English word is on the second syllable, following Latin accent rules, which require that a penult (next-to-last syllable) must be accented if it has a long vowel. In the Greek pronunciation, the first syllable is accented, because the Ancient Greek rules of accent do not force accent to the penult unless the ultima (last syllable) has a long vowel.

The initial /h/ is dropped in many European languages; Finnish is one of those that preserve it (e.g. in Heureka), German is another one (cf.Heureka).

Archimedes

This exclamation is most famously attributed to the ancient Greek scholar Archimedes; he reportedly proclaimed "Eureka!" when he stepped into a bath and noticed that the water level rose — he suddenly understood that the volume of water displaced must be equal to the volume of the part of his body he had submerged. This meant that the volume of irregular objects could be measured with precision, a previously intractable problem. He is said to have been so eager to share his realisation that he leapt out of his bathtub and ran through the streets ofSyracuse naked.

Archimedes' insight led to the solution of a problem posed by Hiero of Syracuse, on how to assess the purity of an irregular golden votive crown; he had given his goldsmith the pure gold to be used, and correctly suspected he had been cheated, by the goldsmith removing gold and adding the same weight of silver. Equipment for weighing objects already existed, and now that Archimedes could also measure volume, their ratio would give the object's density, an important indicator of purity.

This story first appeared in written form in Vitruvius's books of architecture, two centuries after it supposedly took place. Some scholars have doubted the accuracy of this tale, saying among other things that the method would have required precise measurements that would have been difficult to make at the time. For the problem posed to Archimedes, though, there is a simple method which requires no precision equipment: balance the crown against pure gold in air, and then submerge the scale with crown and gold in water to see if they still balance.