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Thursday, March 28, 2024

Science Corner – Imagine Millions, Billions and Trillions

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What’s the difference between a million and a billion? If you answer “Just one letter” you are literally correct, and for most of us they are just very big numbers that we cannot grasp. Until recently, they had no use. A shepherd might need to count a hundred sheep, but never a thousand, let alone a thousand thousands, which is a million. We all know billionaires are very rich, but do you realize that a billion dollars can buy 1,000 million-dollar homes?

In science we often deal with unimaginably huge numbers. For example, we estimate that our Milky Way galaxy, like most galaxies, contains about a hundred billion (100,000,000,000 = 1011 because eleven zeros) stars. Of course, we haven’t counted them all, but we can count those in a small patch and multiply by the ratio of areas.

Coincidentally, this is also roughly the number of galaxies in the visible universe, and the number of neurons in your brain!

In science we often make rough estimates – we don’t always need to be precise. On a beach, I would teach my kids to estimate the number of grains of sand. This is much easier with meters than with inches, feet and yards (a yard is 0.91m). Guesstimate the length, width and depth as, say, 100m, 10m, and 1m, so the volume is 1000 (103) cubic meters. Roughly.

Since 1m is 1,000mm, there are a billion cubic mm in a cubic meter and so a trillion (1012) cubic mm on the beach. Now you are all done: a few trillion grains of sand. If each grain of sand were a dollar, that is the National Debt! An astronomical number, but not infinite!

Speaking of astronomical, we think that most stars have planets. Now – pure guesses: even if only one percent of the planets have conditions good for life, and only one percent of those actually have some form of life, that is still ten million planets in our galaxy with life. If the probability that a planet with life evolves to be an advanced society is 0.1 percent, that makes ten thousand such civilizations in our galaxy. Ours may be the only one, but that seems unlikely.

But don’t worry, the galaxy is so big that it is extremely unlikely that extraterrestrials are closer than 100 light years (500 trillion miles) away. At that distance they could be listening to World War I news on the radio, and probably, wisely decide to leave us alone.

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Michael Albrow
Michael Albrow
Michael Albrow is a scientist emeritus at Fermilab, Batavia and a member of Naperville Sunrise Rotary. Born in England, Mike lived in Switzerland and Sweden before settling in the U.S. 25 years ago.

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