Photo by: Getty Images

Getty Images

Feathers and Bowling Balls Act Strangely in a Vacuum

You can recreate your own version of this famous experiment.

August 01, 2019

Sometime in the third century B.C., Aristotle wrote that heavy objects fall toward Earth faster than lighter ones. His explanation for this behavior was profoundly influential, sophisticated for its time, and almost completely wrong. Almost 2,000 years later, Galileo proved that heavy objects and light objects fall to Earth at exactly the same rate. You can perform his experiment yourself.

No, This Doesn't Defy Gravity

At first glance, it's easy to side with Aristotle. If you drop a feather and a bowling ball from the same distance anywhere on Earth, they will fall at different rates. The feather will drift breezily to the ground while the bowling ball plunks downward immediately. But this explanation leaves an important factor out of the equation: air resistance. Since the feather is so light, air pressure acting on it from all directions is strong enough to counteract the force of gravity, which acts on it uniformly regardless of its weight.

Galileo proved Aristotle wrong with a simple stroke of genius — he used two cannonballs (bowling wasn't popular in 16th century Italy, but cannons were) and dropped them both off of the Leaning Tower of Pisa. If Aristotle was right, then the smaller cannonball should fall at a slower rate than the larger one. Instead, they both fell at the same exact speed: 9.8 m/s². Galileo's experiment became one of the most important pieces of the puzzle that Isaac Newton would later use to establish the modern theory of gravity.

You can recreate your own version of Galileo's experiment by tying a feather to a bowling ball and dropping them both at the same time. The feather-bowling ball duo doesn't fall at a slower rate because the feather is lighter than just the bowling ball alone — instead, they both fall at exactly the same rate. Similarly, if you pump all of the air out of a glass chamber to create a vacuum, you can drop both the feather and the bowling ball — no strings attached — and watch them hit the ground at the exact same time.

No Vacuum Chamber, No Problem

This experiment doesn't necessarily require a cumbersome vacuum chamber. Apollo 15 astronaut David Scott famously recreated this experiment on the moon in 1971 using a falcon feather and a hammer. Scott, an MIT-educated aeronautics engineer, knew his physics, so the fact that the feather and hammer hit the surface of the moon at the same time was no surprise. The moon has an atmosphere 10 quadrillion times less dense than the Earth's — so weak, in fact, that statically charged moon dust levitates around 10 centimeters above the surface of the planet. Despite the fact that modern audiences know what the outcome of Scott's experiment is, the live broadcast remains a sight to behold and a historical treasure.

This article first appeared on Curiosity.com.

Next Up

The Secret of Pluto’s Ocean

When we think of an ocean, we don't necessarily think of Pluto. If we can’t see the liquid water, why do astronomers think it’s there?

Check out the Earth’s 800,000 Year Old Battle Wound

Scientists may have discovered the location of an ancient buried crater, a result of a meteorite that barreled into the Earth some 800,000 years ago.

Last Call for the King of Planets

This month Jupiter is entering conjunction which means it's the last chance this year to catch a glimpse of the largest planet in our solar system.

Welcome to the Surface of Mars

Through the use of cutting-edge instruments, scientists finally have the opportunity to probe deep beneath the surface and ascertain exactly how the terrestrial planet formed.

The Coronavirus: What You Need to Know About the Virus

As the death tolls rise, Coronavirus is on the minds of people all over the world. Learn about this new virus and how we got here. Originally published: 2/20/2020 Updated: 3/9/2020

Scientists Have Discovered Enormous Balloon-Like Structures in the Center of Our Galaxy

There's something really, really big in the middle of our Milky Way galaxy — one of the largest structures ever observed in the region, in fact.

July in the Sky: Celestial Events Happening This Month

With eclipses, meteor showers, and more, it's a busy month in the night sky this July. Take some time this summer to look up and enjoy these cosmic wonders.

Get Celestial with Lowell Observatory LIVE!

Our friends at Lowell Observatory are serving up our solar system on a platter live!

Celebrating Hubble's 30 Year Legacy

Three cheers for the Hubble! First launched in 1990 aboard the Space Shuttle Discovery, the storied space telescope is celebrating is thirtieth year in lonely orbit around the Earth.

Survival Chemistry: The Ingredients for Life on Earth

Oxygen, hydrogen, carbon, and a few other elements from the periodic table make up 99% of our bodies.