tube, which responded to changes in temperatures. He arbitrarily decided that the dif-
ference between water freezing and boiling—32 degrees Fahrenheit and 212 degrees
Fahrenheit, respectively—would be 180 degrees.
The Kelvinscale was invented in 1848 by Lord Kelvin (1824–1907), who was also
known as Sir William Thomson, Baron Kelvin of Largs. His scale starts at 0 degrees
Kelvin, a point that is also known as absolute zero,the temperature at which all mole-
cular activity ceases and the coldest temperature possible. His idea was that there was
no limit to how hot things can get, but there was a limit to how cold. Kelvin’s absolute
zero is equal to 273.15 degrees Celsius, or 459.67 degrees Fahrenheit. So far, sci-
entists believe nothing in the universe can get that cold.
TIME AND MATH IN HISTORY
How are mathematicsand the study of time connected?
Mathematics is definitely tied to time. There has long been a need in human civilizations
to record many sequences of events, especially those in nature that affected people. For
example, the changing of the seasons was important to know, as it influenced the planting
and growing of crops, when rivers would flood, and even when weather would change—
from monsoon rains and harsh droughts to potential blizzards. The first such timekeepers
counted the changing days and years by the movement of stars, the Sun, and the Moon
across the sky, all of which are activities that included simple mathematical calculations.
What is some of the earliest evidenceof keeping time?
No one agrees which culture(s) first invented timekeeping. Some historians and
archeologists believe that marks on sticks and bones made by Ice Age hunters in 55
MATHEMATICS THROUGHOUT HISTORY
What are the methods for converting
temperatures between the various scales?T
he following lists ways to convert from one temperature scale to another
using, of course, simple mathematics:Fahrenheit to Celsius:C°(F°32) / 1.8; also seen as (5/9)(F°32)
Celsius to Fahrenheit:F°(C°1.8) 32; also seen as ((9/5)C°) 32
Fahrenheit to Kelvin:K°F°32 / 1.8 273.15
Kelvin to Fahrenheit:F°(K°273.15) 1.8 32
Celsius to Kelvin:K°C°273.15
Kelvin to Celsius:C°K°273.15