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Units that Measure Up: From Giga-watts to Hella-tons

UC Davis physics student Austin Sendek has proposed that the prefix “hella-” be used as a standard prefix for 10^27th power. If that sentence doesn’t make much sense to you, you’re in luck – there’s an explanation in Part 1 below. If you could parse the sentence but think it’s a rather lame joke, don’t make up your mind quite yet – I’ll lay out the surprising history of some units that might make you reconsider in Part 2.

Part 1: Giga-what, giga-who?

Most of the time you and I can get by with some pretty small numbers. I might buy a 5-pound bag of flour or ask you to lend me 20 dollars, and there’s nothing wrong with that. But if you work in science, engineering, economics, or other similar fields you inevitably need to count or measure things that are really, really big, and you don’t want your readers to spend all their time counting digits rather than appreciating your brilliant prose.

This is why we have the International System of Units (SI) and its prefixes. When Doc Brown is pouring pilfered plutonium into a DeLorean to send it to the future, rather than wrapping Marty’s head around 1,210,000,000 watts he can simply exclaim, “1.21 gigawatts!” When Commander Data is downloading MP3s, he can say he’s got 100 petabytes to fill, rather than boring Geordi with 100,000,000,000,000,000.

But what happens when you get past peta- (10^15), exa- (10^18), zetta- (10^21) and yotta (10^24)? Right now you’re stuck. At this point we’re in the range of some ridiculously big numbers, but the universe is ridiculously big. The mass of the Earth is about 5,980,000,000,000,000,000,000,000 grams, or 5,980 yottagrams – but who’s got time for thousands of yottagrams?

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