Q: What is the biggest number?

A: The immediate answer to this question is infinity. After all, no matter what number you offer to me, I can always say, “yeah, well that number, plus one.” Science gives us a different answer though. The largest number for which we have a unique name is a Sentillion. How big is a sentillion?

Imagine a Million. It’s a big number, but not so big you can’t wrap your mind around it. A million pennies costs $10,000. A million kilometers is about 25 times around the earth. Light travels a million kilometers in just over three seconds. A stack of one million sheets of paper would be about a kilometer high. A million is 1,000,000.

Ok, so you have in your mind the concept of a million? Good. Now, imagine a Billion. That’s one thousand million. Governments deal in billions of dollars. There are a few billionaires in the world. A multi-millionaire could own one billion pennies. Light travels just over a billion kilometers in an hour. Computers regularly come with a gigabyte (one billion bytes) of ram. Hard drives are also measured in gigabytes. A billion is 1,000,000,000.

Billion wasn’t so tough. Now, try Trillion. A trillion is a million million, or a thousand billion. The US government has a budget in the trillions of dollars. Only a multi-billionaire could afford a trillion pennies, but in the history of the planet, a trillion coins have not yet been produced worldwide. Light travels a trillion kilometers in around six weeks. Some expensive computer drive arrays can hold a terabyte (trillion bytes) of data. A trillion is 1,000,000,000,000.

Try a quadrillion – you have to start thinking dynamically here. For example, aside from being a billion million (or a million billion, or a thousand trillion), the earth’s oceans hold roughly 50 quadrillion gallons of water. It would take light 100 years or so to traverse a quadrillion kilometers. A quadrillion is 1,000,000,000,000,000.

So, what’s this have to do with a sentillion? Well, a sentillion is a…

Thousand quadrillion quadrillion quadrillion quadrillion quadrillion quadrillion quadrillion quadrillion quadrillion quadrillion quadrillion quadrillion quadrillion quadrillion quadrillion quadrillion quadrillion quadrillion quadrillion quadrillion. That’s a one with three hundred and three zeros behind it.

It’s very hard to contemplate something to compare a sentillion to. For example – children often ask how many grains of sand there are in the world. Hah. At best, you're looking at a few hundred quadrillion.

Stars in the universe? A mere few million quadrillion. Mass of the universe itself? Well, that’s a big number (something close to ten million quadrillion quadrillion quadrillion quadrillion) which really isn't even close.

In fact, if you counted every single atom in the entire universe (a hundred million quadrillion quadrillion quadrillion quadrillion quadrillion quadrillion or so) you wouldn't even be near a sentillion. Atoms aren't the smallest thing we can measure, but turns out this fact doesn't really matter.

The smallest possible length we can measure in the universe (as far as our current theories tell us) is something on the order of a quadrillionth of a quadrillionth of a meter - a decimal point, followed by thirty zeros, and then a one. If you filled the entire universe with dots that tiny you’d still not only be short, but be so short that you’d need to fill a thousand quadrillion quadrillion quadrillion (and so on about a dozen more times) universes to count just one sentillion dots.

So why, if there is nothing ever that could be a sentillion in length, width, height, volume, mass, or any other set of parameters we choose to use, did we bother to name such a large number at all?

Because there is one infinite thing in this universe - a bored scientist’s desire to "one-up" another bored scientist… plus one.

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