## Friday, March 13, 2015

### Once in a Lifetime PI Day Saturday

Saturday is PI day.  It's a very special PI day because it corresponds to the exact date:

3-14-15
3.1415...

If you continue the date to include the hour, minutes and seconds, it would read:

3-14-15  9:26:53
3.141592653

Check out the commemorative PI t-shirt.

This is all great but why is PI so important?  Its a day to teach kids math by making it fun. Your kids might have PI day activities planned at school today (Friday).

I'm sure back in 1737 when Leonard Euler first used the symbol π, he never envisioned the fascination with π that developed since.  There are t-shirts, π plates (yes, I have two), π mugs...and on and on. Novelty websites have just about every π trinket you can think of!

What is PI " π"?

PI is the number that represents the ration of a circle's circumference to its diameter.

The Interesting part is that PI is a non-repeating, never ending decimal so its very nature is an approximation. Mathematicians have tried to find a patterns that might define π since ancient times. Archaeologists believe that the ancient Egyptians constructed the Great Pyramid of Giza with knowledge of π. Greek mathematician Archimedes was the first to calculate a range for π using polygons.

Throughout its history, π has become a fascination among mathematicians and computer programmers. Welsh mathematician William Jones was the first to use the symbol π to represent the ratio of a circle's circumference to its diamater in the early 1700s. In the 1940s, a little over 1000 digits of π were known.

As we entered the computer age, the calculation for more digits became a test for computer system efficiency and accuracy. In 2014, scientist Ed Karrel calculated more than 10 QUADRILLION decimals of PI.  Here is his blog.

To put the number of digits in Ed Karrel's calculation into perspective, you only need 39 digits of PI to calculate the circumference of the observable universe (assuming it's a sphere) to the accuracy of a width of the inside of an atom!

To put it another way, if you were to recite EVERY digit, it would take you 317,000,000 years to complete. You'd need to start before the dinosaurs were alive in order to finish today!

All of this great if you are a math or computer geek. But why should the rest of us care?

PI is present in every aspect of our lives. PI is used in most calculation in the development of all the world's infrastructure. All communications, CAT scans, MRI machines, genetic research, propulsion systems (space and military aircraft), quantum physics....the list goes on.

Famous scientific discoveries and the math that describes them incorporate PI:

* The calculation for determining the horsepower of your car has PI in it.

* Einstein's famous equations that describe relativity which is now directly applied in
satellite calibration has PI in it. Here it is in very simple form:

* The math that determines electric force (electricity) includes PI.

*  How about the speed and volume of blood flow inside the first artificial heart? You bet.
PI is included in that calculation too.

* Want to figure out the position of two planets nearest to the earth? You need PI.

* Radio communications, cellphones, GPS satellites (see Einstein's equation above) computer hard drive/processor technology were both developed using mathematics that incorporates the number "PI".

* Airlines use PI to calculate flying distance around the earth

* Manufacturing uses PI to figure out how much of a substance will fit into a volume
of circular or cylindrical space

You might not like math. You might not get PI.  Just remember that PI (3.14159...) is integrated into our everyday life unlike any other number. Without it, your daily life would be totally different.