Do you know of anything that goes on and on forever? The school day may seem to last forever, but it does have an end! Mathematicians have a special word for things that go on forever. It’s called “infinity.“

Have you ever used a number line in math class? If so, you may know that there’s no end to it. It goes on forever in both directions — both positive and negative. That’s an example of infinity.

The idea of infinity is used mainly in the fields of math and physics. It describes a quantity without end. In fact, infinity comes from the Latin word *infinitas. *That word means “unboundedness.”

Infinity has its own symbol:∞. It’s called the lemniscate, which means “ribbon.”John Wallis began using this symbol for infinity in 1655. Some believe he based it on the Roman numeral for 1,000. Others believe the symbol was based on the last letter of the Greek alphabet: omega.

In math, infinity has many uses. For example, the number pi is an infinite decimal. That means it goes on forever. But infinity is more than just a large number.

Would you believe that there can be different sizes of infinity? It’s true! Consider this: there is an infinite number of positive whole numbers. There is also an infinite number of even positive whole numbers. Both these sets of numbers are infinite. However, the set of infinite positive whole numbers is twice as large!

Fans of astronaut Buzz Lightyear know that his catchphrase is “To infinity…and beyond!” That’s right, infinity is even used in the study of space! Experts use it when they study the size of the universe. Does space simply go on forever? No one knows for sure. What scientists do know, though, makes many of them think that the universe is infinite.

The idea of infinity is also used in philosophy. One example is the infinite monkey theorem. To understand this idea, picture a monkey randomly hitting keys on a keyboard. Now, imagine that the monkey has an infinite amount of time to keep hitting keys. The infinite monkey theorem says that, eventually, that monkey will type some given text. They might end up with *Moby Dick* or the complete works of Shakespeare.

Can you think of any other uses for infinity? There aren’t many things that go on forever! What do you wish was infinite? Your favorite meal? Maybe recess? We can always hope!

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Standards:
*CCRA.L.3, CCRA.L.6, CCRA.R.1, CCRA.R.2, CCRA.R.4, CCRA.R.10, CCRA.SL.1