Overcome the Curse of Knowledge by bringing numbers down to earth

Experts may be like Icarus in the painting shown above illustrating that Greek myth. We can soar so far above our audience it is difficult to see their earthbound view. Nick Morgan said this on April 25, 2019 in a post at his Public Words blog titled How can you make a technical subject interesting?:

“You’re too deep in the field to remember, but the interests of a general audience are so primitive by your standards that they don’t speak your language, they don’t understand your numbers, they don’t hold their breath over what you find controversial, and they don’t recognize the stars in your sky. So you need to start, not with your expertise, but with your beginner’s mind.”

Chip and Dan Heath’s 2007 book Made to Stick discussed it as The Curse of Knowledge. They said:

“Once we know something, we find it hard to imagine what it was like not to know it. Our knowledge has ‘cursed’ us. And it becomes difficult for us to share our knowledge with others, because we can’t readily re-create our listeners state of mind.”

 On May 17, 2019 I had blogged about Telling a gigantic story: the B reactor tour in Hanford, Washington. That nuclear reactor produced the plutonium for the Fat Man bomb dropped on Nagasaki, Japan which led to the end of World War II. It was located on the south bank of the Columbia River. I mentioned that the fission reaction generated 250 million watts (Mw), and they circulated 30,000 gallons of cooling water per minute through the aluminum tubes holding the uranium in the core to remove that heat.

How could I bring 250 million watts to life for my hometown of Boise? An electric two-slice toaster uses around 850 watts, and a toaster oven uses 1200 watts. In 2017 Boise had a population of  226,570 people. Imagine if everyone in town simultaneously left on a toaster or toaster oven!

And how could I explain what 30,000 gallons per minute means? Current showerheads have a flow rate of 2.5 gallons per minute. The capacity of Taco Bell Arena (just renamed ExtraMile Arena) where the Boise State Broncos play their basketball games is a bit more than 12,000. Imagine all 12,000 people taking a shower at once.

My career as an engineer has made me so familiar with metric prefixes for thousands (kilo or k) and millions (Mega or M) that I don’t even have to think about them. I have to think just a little about the prefixes for billions (Giga or G), trillions (Tera or T) and quadrillions (Peta or P).  

A ratio might the best way to compare two things. The Wikipedia article about the Fat Man bomb said it had a yield of 21 kilotons (of TNT), and that the bomb weighed 10,300 pounds. That is 21,000 tons of TNT and the bomb weighed 5.15 tons. Then the ratio is 4078. That is, the nuclear explosive was 4078 times as powerful as a conventional TNT bomb. 

Some numbers are difficult because they truly are huge. On July 15, 2011 I blogged about the Kennecott Bingham Canyon open pit copper mine west of Salt Lake City in a post titled What can we say about a really big hole in the ground? The Wikipedia article says every day they dig up 450,000 tons of ore and haul it away using a fleet of 64 giant dump trucks that each carry a load 255 tons.

In my blog post I noted that the daily load was described as a multiple of 50-ton humpback whales. But humpback whales are not part of our everyday experience. Have you ever been at a whale crossing? But most people have sat in a car waiting at a railroad crossing and seen 110-ton hopper cars of coal in a train. 450,000 tons corresponds to 4091 of those hopper cars, or roughly a hundred trains each with 40 cars! Similarly, each of those 255 ton dump trucks carries ~2.3 times what a hopper car does.

Why do they dig up so much material at Bingham Canyon? Wikipedia also says the mine produces 300,000 tons of copper per year, which converts to 821 tons per day. Divide that by 450,000 and you get that the ore only contains 0.183 % copper. (There are other more precious metals as well).  

Some numbers just sound big until you ask what a person’s share of them is. Back on August 17, 2011 I blogged about How to make a large number incomprehensible – or comprehensible. I discussed an article which said that in the U.S. we use 5.7 billion gallons of water per day to flush the toilets. But when you divide that among a population of 308 million it becomes 18.5 gallons a person per day. That article had claimed 5.7 billion gallons was incomprehensible - it isn’t. It’s about 9% of what goes over Niagara Falls. If I were discussing this here in Boise I would instead compare with Shoshone Falls.

Costs based on the calendar can be expressed several ways. Netflix doesn’t say they charge me $189 per year – it’s billed as $13.99 per month. Charities like Shriners or Wounded Warriors Project don’t advertise $228 per year – it’s just $19 per month. Coast to Coast AM has an Insider program that lets you listen to an archive of radio shows for $54.99 a year – which they say is only 15 cents a day.