This is to alert Americans to innocent words from their dialect that Australasians (Australians and New Zealanders) may find offensive or confusing. The 2001 policy of New Labour to abolish the office of Lord Chancellor has been seen as a rushed 'back-of-an-envelope' plan.The spread of the Internet provides opportunities to offend or confuse correspondents whom you imagine speak the same dialect of English as you. Īn important Internet protocol, the Border Gateway Protocol, was sketched out in 1989 by engineers on the back of 'three ketchup-stained napkins,' and is still known as the three-napkin protocol. Nobel laureate Charles Townes describes in a video interview for the University of California, Berkeley on the 50th anniversary of the laser, how he pulled an envelope from his pocket while sitting in a park and wrote down calculations during his initial insight into lasers. In these notes Weisskopf used back-of-the-envelope calculations to calculate the size of a hydrogen atom, a star, and a mountain, all using elementary physics.

When she heard that the 100-inch telescope there is used to determine the shape of the universe, Elsa Einstein stated 'Well, my husband does that on the back of an old envelope.' Īnother example is Victor Weisskopf's pamphlet Modern Physics from an Elementary Point of View. Ī story is told about how Albert Einstein and his wife visited the Mount Wilson Observatory in 1931. He estimated 10 kilotons of TNT the measured result was 18.6. By measuring the distance they were blown, he could compare to a previously computed table and thus estimate the bomb energy yield.

As the blast wave reached him, Fermi dropped bits of paper. The most famous instance came during the first atomic bomb test in New Mexico on 16 July 1945. įermi was known for getting quick and accurate answers to problems that would stump other people. He went on to develop a series of sample calculations, which are called 'Fermi Questions' or 'Back-of-the-Envelope Calculations' and used to solve Fermi problems. In the hard sciences, back-of-the-envelope calculation is often associated with physicist Enrico Fermi, who was well known for emphasizing ways that complex scientific equations could be approximated within an order of magnitude using simple calculations.

Back of the napkin idiom