Explosion And Implosion

Stupid Question ™
March 14, 2005
By John Ruch
© 2005

Q: What’s the difference between an explosion and an implosion?
—Daniel (age 10), from the Internet


A: In everyday language, an explosion is a violent burst directed outward, while an implosion is a violent burst directed inward.

For example, fireworks are explosions caused by superheated gases and flames bursting outward from the center of a rocket.

An example of an implosion is a submarine under very deep water losing its air pressure because of a leak and then being crushed from the outside in, because of the pressure of the water.

The terms “explosion” and “implosion” almost always imply that pressurized gases or liquids are involved. If you jump on a soda can, that’s also something collapsing from the outside in, but it would rarely be called an implosion.

The words have a history that may surprise you, because “explosion” originally had nothing to do with bombs or blasts.

The verb “explode” is taken straight from the Latin word explaudere (or explodere), which literally means “to clap off.” It’s a theater term referring to a bad actor being forced off the stage by audience clapping. The clapping in this case was not a good thing, like we think of it today.

In Latin, it also came to mean expressing contempt for anything.

This was the meaning the word had when it came into English, too, around the early 1500s. In fact, it’s a meaning the word still has today, in phrases such as, “His argument was exploded.”

In the mid-1600s we start to see another meaning of the word, pretty close to what we use today: to force air or some other gas out with a loud sound. This is where the linguist term “explodent consonants” comes from, which means the kinds of letters we pronounce by blowing out air.

By the late 1700s, the word took on its full, common meaning of a violent, inside-out burst.

The Romans had a different word for our common meaning of “explode.” They used displodere, which roughly means “to clap into two pieces.” It seems to have referred especially to bladders, used for holding water and other liquids or gases, bursting with a loud sound. In the 1600s, the English version of the word, “displode,” was used to mean what “explode” means today.

“Implosion” is a modern invention from the 1800s, a reversal of “explode”; it literally means “to clap (or burst) inwards.”

“Ex-” in “explosion” means “off” or “out.” The “im-” in “implosion” means “in” or “inward.”

Why “im-” instead of “in-,” which would seem to make more sense?

Well, it really is “in-.” In Latin words that began with “in-” the letter “n” was changed to an “m” if it came before the letters “i,” “m” or “p.” That’s because the “n” sounds like an “m” in front of those letters anyway.

Try it yourself. If you say, “inplosion,” it sounds like “implosion” because of the way the letter sounds hit each other.