los angeles — Math nerds and candy lovers unite to celebrate Pi Day every March 14, the date that represents the first three digits of the mathematical constant Pi.
Representing the ratio of a circle’s circumference to its diameter, pi is approximately 3.14159 – but its numbers go on forever. Maybe you used it in school to calculate the area of a circle or the volume of a cylinder. But the applications of Pai are endless and it is a part of every corner of our world.
The holiday was created in 1988 by Larry Shaw, a physicist at the Exploratorium Science Museum in San Francisco.
“He had a very open, broad view of the world, and he saw an opportunity with this number, and the mathematical concept, to invite people into the joy of learning mathematics,” said Sam Sharkland, the museum’s director of public programs, who worked with Shaw before his death in 2017.
While it started as a small staff celebration featuring pie, it soon turned into a large procession as hundreds of visitors walked around the Bai shrine, each bearing a number. Attendees often show up early to claim their favorite number at the show. One of the women with the symbol tattooed on her neck comes every year and walks near the front carrying the Bay flag, Sharkland said.
The celebration begins at 1:59 p.m., denoting the next three numbers of pi.
Here are some of the ways pi is used in cutting-edge science.
In the field of mechanical and aerospace engineering taught by Artur Davoyan, pi is so fundamental that it would be difficult to pinpoint a single use case for it, he said.
Pi is part of every formula that can be used to perform any calculation, such as spacecraft motion, materials and how they work, or propulsion systems, said Davoyan, the UCLA professor.
Anything that is round or has periodic or repeating properties — such as radio waves — includes pi. Even irregular squares or blobs can be divided into a series of progressively smaller circles and calculated using pi, Davoyan said.
Davoyan’s research investigates how to create new propulsion systems to more quickly send spacecraft to the far reaches of the solar system to collect information and send it back to Earth. He pointed to NASA’s Voyager 1 and 2, which were launched in 1977 but did not reach interstellar space until 2012 and 2018.
To send a signal to those space probes, NASA must calculate the exact position of Earth in its orbit around the sun and design communications antennas using pi. Scientists then use pi again when receiving and deconstructing complex signals that are sent to Earth.
“Suppose aliens are sending us something, something we don’t know how to handle,” Davoyan said. “So the first thing you would do is try to break it down into simple functions…and it turns out that when you do this process, you naturally have Pis in it.”
Pi also appears frequently when studying small volumes of liquids.
Dino Di Carlo, chair of the Department of Bioengineering at UCLA’s Samueli School of Engineering, conducts research that involves creating small molecules from polymers that serve as tiny test tubes for cells. This is used as an important tool to closely examine cells and learn about their functions and what’s inside.
Di Carlo said the pi constant is used to calculate how those droplets form, surface tension calculations that determine how droplets can break apart, and how researchers can control the size of those droplets.
Di Carlo uses this technique to find antibodies — small proteins that fight diseases in the body — that can block signals made by cancer cells.
Pi is also an important part of the calculations when considering how fluids flow through pipes and barriers. One example of this is when a fluid sample slowly flows sideways in a take-home COVID-19 test.
Di Carlo used these properties to create a new test for Lyme disease that can be completed in 20 minutes, instead of days or weeks as was previously the case.
“As an engineer and scientist, (Bay) is just part of life,” Di Carlo said. “Maybe I took it for granted.”