The Wonders of Science: Physics behind fireworks
by Eric Rasmussen
It’s finally summertime. Swimming pools are open, grills are cooking, and Fourth of July festivities are right around the corner. Of course, July 4th is a celebration of the United States declaring independence. But as we watch fireworks explode in the night sky, this day is also a celebration of quantum physics. After all, a world without quantum physics would be a world without fireworks.
Imagine grabbing a Slinky and giving it a little shake. Now take the Slinky and give it a large shake. The greater the energy, the greater the wave, and the same is true for the electron waves of an atom (as seen in the photo above).
For eons mankind has tried to understand the inner workings of the materials that make up the world. Back in 460 B.C., Greek Democritus first presumed that all material objects were made of smaller objects. These he called atomos, for indivisible. As years passed and technology continued to advance, mankind refined Democritus’ atomic theory, eventually arriving at quantum physics in the 1930s.
Armed with quantum theory, we now know atoms to be made of individual particles: protons, neutrons and electrons. (Protons and neutrons are themselves made from even smaller particles called quarks, but that is a topic for another time.) Protons and neutrons group together to form the nucleus of an atom, and this nucleus is then surrounded by negatively charged electron waves.
Wait…waves? Yes, waves.
We tend to envision electrons as tiny sphere-like structures orbiting the nucleus of an atom like planets around the sun. Quantum mechanics says this is not so; experiments show electrons have no real structure but are instead energy waves smeared around the nucleus of an atom.
The figure above shows an atom releasing a yellow bit of light (energy), thereby freeing one of its electrons to exist in a lower energy level.
Strange as this may sound, to quote astrophysicist Neil deGrasse Tyson, “The universe is under no obligation to make sense to you.”
Lest we think we’re wandering off-topic from fireworks, let’s cut to the clincher:
Imagine grabbing a Slinky and giving it a little shake. Now take the Slinky and give it a large shake. The greater the energy, the greater the wave, and the same is true for the electron waves of an atom (as seen in the photo above).
When an electron receives energy (say…due to an exploding firework), its wave will expand, and the electron will move to a higher energy level.
But what is true for baseballs is also true for electrons: What goes up, must come down. Like baseballs, electron waves want to exist in the lowest energy levels possible, and therefore must give off energy so the wave may shrink.
This is accomplished by emitting a photon — the subatomic particle of light. The figure to the left shows an atom releasing a yellow bit of light (energy) freeing one of its electrons to exist in a lower energy level.
We can identify the chemicals present in the fireworks used on July 4th. Emerald green? That is due to the electrons in barium atoms cascading to lower energy levels. Shimmery yellow fireworks? That’s the work of sodium atoms; whereas red is strontium, and blue is copper.
In fact, atoms not only can emit colors of light, but each chemical has wholly unique electron energy levels. So different atoms can emit characteristic and different colors of light.
Using this magnificent property, we can identify the chemicals present in the fireworks used on July 4th. Emerald green? That is due to the electrons in barium atoms cascading to lower energy levels. Shimmery yellow fireworks? That’s the work of sodium atoms; whereas red is strontium, and blue is copper.
Now we can go forth and position ourselves as the residential geniuses at backyard 4th of July parties. After all, it’s patriotic to love science!
Next month, we will learn how these same properties not only allow us to determine the chemical composition of fireworks, but also of all the stars across the universe!
Photo information (in order of appearance):
https://kaiserscience.files.wordpress.com/2015/09/wave-nature-of-the-electron.gif
https://proxy.duckduckgo.com/iu/?u=https%3A%2F%2Ftse4.mm.bing.net%2Fth%3Fid%3DOIP.dHf-9_-A1rWsA-oK82iMtwHaG4%26pid%3DApi&f=1
Author Eric Rasmussen, BS, M.Ed., obtained his bachelor of science degree at the University of Colorado at Boulder. He majored in ecology and evolutionary biology, and now serves as a Learning Technology Coach at Erie High School and Erie Middle School in the St. Vrain Valley School District, CO.
