Fermi Problem
On a
Monday morning in July, the world’s first atom bomb exploded in the New Mexico
desert. Forty seconds later, the shock waves reached the base camp where the
Italian-American physicist Enrico Fermi and his team stood. After a mental
calculation, Fermi announced to his team that the bomb’s energy had equated
10,000 tons of TNT. The bomb team was impressed, but not surprised. Fermi’s
genius was known throughout the scientific world. In 1938 he had won a Nobel
Prize. Four years later he produced the first nuclear chain reaction, leading us
into the nuclear age. Since Fermi’s death in 1954, no physicist has been at once
a master experimentalist and a leading theoretician.
Like all
virtuosos, Fermi had a distinctive style. He preferred the most direct route to
an answer. He was very good at dividing difficult problems into small,
manageable bits—talent we all can use in our daily lives.
To
develop this talent in his students. Fermi would suggest a type of question now
known as a Fermi problem. Upon first hearing one of these, you haven’t the
remotest notion of the answer, and you feel certain that too little information
had been given to solve it. Yet when the problem is broken into sub-problems,
each answerable without the help of experts or books, you can come close to the
exact solution.
Suppose you want to determine Earth’s
circumference without looking it up. Everyone knows that New York and Los
Angeles are about 3,000 miles apart and that the time difference between them is
three hours. Three hours is one eighth of a day, and a day is the time it takes
the planet to complete one rotation, so its circumference must be eight times
3,000 or 24,000 miles. This answer differs from the true value, 24,902.45 miles,
by less than four percent.
Ultimately the value of dealing with
everyday problems the way Fermi did lies in the rewards of making independent
discoveries and inventions: It doesn’t matter whether the discovery is as
important as determining the power of an atom or as small as measuring the
distance between New York and Los Angeles. Looking up the answer, or letting
someone else find it, deprives you of the pleasure and pride that accompany
creativity, and deprives you of an experience that builds up self-confidence.
Thus, approaching personal dilemmas as Fermi problems can become a habit that
enriches your life. |
