On Thu, Jul 23, 2009 at 6:38 PM, Anurag Goel<[email protected]> wrote: > GPA Notes 7/23/09 > > Who: Walter, Caroline, Jennifer, Anurag > > 10:45: Set-up computers and projector. Walter worked on Clock program in > Turtle Art > > Walter: Today we are going to use the turtle to play with clocks. (Walter > shows the kids the clock program he made in Turtle Art. The kids compare > Walter's clock with the other clocks in the room. > > Walter: Why do we use 12 numbers on the clock instead of 10 or 6 or 5?
And why is the beginning hour of the day 12 and not 0 or 1? Because Leonardo of Pisa (Fibonacci) found out about Arabic numerals and published his book, Liber Abaci, during the Crusades. The Catholic Church took the position that the (Hindu/)Arabic 0 was an infidel invention, counter to the essential doctrines of Christianity. That is, that nothingness is irreligious when religion is founded on Creation. At that time clocks only existed in monasteries and cathedrals. Household clocks and pocket watches stayed with Roman numerals, and we are still stuck with this prejudice in the US. The situation is different in the sciences, in the US military, and in almost all other countries. All of them use a 24-hour clock that runs from 0:00:00 to 23:59:59 every day. This also gets rid of the ambiguity about 12 AM and 12 PM, and the resulting need to say 12 noon or 12 midnight. And the other ambiguity about 12 midnight--Which day is it? 0:00 is clearly part of the day that follows it. Clock time is the canonical example of a ring in mathematics, where you have addition, subtraction, and multiplication, but not division. -- Silent Thunder (默雷/धर्ममेघशब्दगर्ज/دھرممیگھشبدگر ج) is my name And Children are my nation. The Cosmos is my dwelling place, The Truth my destination. http://earthtreasury.org/worknet (Edward Mokurai Cherlin) _______________________________________________ IAEP -- It's An Education Project (not a laptop project!) [email protected] http://lists.sugarlabs.org/listinfo/iaep
