PI day: Why is PI important?

It's one of my favorite days of the year!  A day when geeks of all ages can show off their PI stuff and skills at recitation.  I used to know PI to 75 digits. Your kids might have PI day activities planned at school today. 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 non-repeating and never ending so its very nature is an approximation. Mathematicians have tried to find patterns within 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 it's history, π has become a fascination among mathematicians and more recently computer programmers. Welsh mathematician William Jones was the first to use the symbol π to represent the ratio of a circle's circumference to it's diameter in the early 1700s. In the 1940s, a little over 1000 digits of π were known.

As of July 2024, the record for PI calculation is 202 trillion Digits.

Read about it HERE.

The last 50 digits are:  5683914937 4658179610 2004394122 9823988073 3622511852

In 2014, scientist Ed Karrel calculated more than 10 QUADRILLION hexadecimal digit of PI.

  Using hexadecimals make it faster to calculate. Converting hex to base 10 numbers which we all use each day is very difficult when you have these many digits according to Ed.  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 equation that describes 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.

How Common Are Spring Temperature Swings In Northern Ohio?

Our human nature is an exercise in self-deception. In the case of weather, our biases can undermine how we look at weather forecasts and past weather events. I like to call it "Behavioral Meteorology". Here's is an example that I guarantee has been said thousands of times over the last several days: "This Ohio weather is crazy! I don't remember changes like this. Wait five minutes and it'll change."

Just look at the high temperatures over the last 2 weeks. 46° to 28°.   40° to 63°.  33° to 52°. Plenty of ups and downs. It's easy to draw the conclusion that these big changes are unusual. 

Look at the temperature forecast through St. Patrick's Day across the eastern US.

But when we look at the entire middle of the country, the locations that see the greatest frequency of day-to-day temperature change might surprise you. The central US -- Eastern Nebraska, northeastern Kansas, northwestern Missouri, portions of Iowa and southern South Dakota -- experience the largest day-to-day temperature swings especially in March and April. Ohio is on the list but no where near the top.

How did I figure this out? I downloaded the high temperatures for each day for 20 cities over the last 50 years. I found the day-to-day high temperature differences and counted up the instances when it was more than 20 degrees. I plotted the results on the map above. For northern Ohio, I tabulated the totals for each month and graphed them below.

This year was the coldest in northern Ohio in a decade (winter of 2014-15). The number of days with high temperatures under 30 was the highest in 7 years. We had triple the number of days with snow on the ground compared to last winter. Large high temperature changes this winter only happened 4 times of at least 15 degrees.

Snow and cold in December through February has been replaced with rain and milder air. These warmer changes are welcomed. But subconsciously, they make us feel uneasy as we try to make sense of rapid temperature changes historically.  Psychologists call this "Cognitive Dissonance". None of us like to feel uncertain or conflicted.  We all have a built in motivation to reduce conflicting ideas by altering the existing conditions in our mind to create consistency. How many times recently have you had a conversation with someone and they said, “What is the deal with this crazy weather…what is going on here?”

Our weather perceptions are powerful.

Here a chart showing the March-April-May instances since 1950 where the high temperatures change more than 20 degrees day-to-day. The average is between 4 and 6 each spring. No big changes over the years in northern Ohio.

We view the weather through our own senses. We interpret all of this information through our own individual frame work. This frame work is built through our own experiences coupled with a hard-wired lens that shapes what/how we view what occurs around us.  We are inclined to favor information that reinforces our comfort level and preconceived notions. This is called a "Confirmation Bias". The problem is that by creating "consistency" through favoring information, we can create a new false interpretation of the weather which we believe to be true. In a nutshell, our own human nature deceives us. Our biases "cloud"--no pun intended--our judgment of the weather changes.

As much as we perceive these fluctuations to be a new thing here in northern Ohio, it is quiet common in early spring. Will these big changes continue in the weeks ahead?  Just look at the temperatures over the next 2 weeks!