Hey there, it's Stephen Dubner from Freakonomics Radio, and I am busting into this

Economics of Everyday Things episode to tell you about two upcoming Freakonomics Radio live shows

in San Francisco on January 3rd and in Los Angeles on February 13th. For tickets, go to Freakonomics.com

slash live shows, one word. I am told that tickets are going fast, so you might want to do this

soon. Again, that is Freakonomics.com slash live shows, January 3rd in San Francisco, February 13th in L.A. I'll be there, and I hope you will too.

One more thing while I have you. If you like the episode on helium you are about to hear,

check out the two recent Freakonomics radio episodes on the Macy's Thanksgiving Day Parade,

which, as you can imagine, uses quite a bit of helium.

As always, thanks for listening.

Most of us have gone to a party store to buy balloons, and the process is pretty simple.

You pick out the color or design you want, an employee fills it up with gas from a

big cylinder behind the register, and it rises as if possessed by a spirit.

I mean, imagine going back to a time before balloons, and that you brought out this object

that would float in the air. It's magical no matter how you slice it.

That's Sophia Hayes.

She's a professor of chemistry at Washington University in St. Louis.

And she says that while the balloon tends to get all the glory at the birthday party,

the stuff inside of it is the true hero.

Where that helium comes from is the decay of radioactive elements.

And as they decay, they spit out an atom of helium.

So every time you see a balloon, that's billions of years of the age of the earth,

undergoing that radioactive decay of a very small number of elements that are in the crust.

...