The U.S. national debt surpassed $40 trillion for the first time on Wednesday. That’s a mind-blowing number.
The number 40 trillion is 4 with 13 zeroes after it. If you laid all those dollar bills out end to end, you’d make it from Earth to the sun and back 20 times.
Spread out over the approximately 343 million people in the U.S., the figure amounts to $116,618 of debt per resident. A single person trying to spend $40 trillion would need 1.27 million years to do it if they spent a dollar every second.
On supporting science journalism
If you’re enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
Forty trillion is more than the number of cells in the human body (about 35 trillion), the distance in miles to Alpha Centauri (25 trillion) or trees on Earth (three trillion). It’s about 40 times more money than the most any human has ever been valued (Elon Musk’s net worth hit $1 trillion in June).
The national debt has been growing prodigiously for some time. It hit what was then a record of $39 trillion in March and had reached $38 trillion last October.
These relative trillions, of course, are hard for the human brain to comprehend. The difference between 38 trillion or 39 trillion and 40 trillion isn’t something we can picture, just as the difference between a billion and a trillion is hard to fathom.
Can you picture the differences between a pile of sand with a million grains, another with a billion and a third with a trillion? I can’t either.
Most people estimate the jump from a million to a billion to be about the same as between a billion and a trillion. But it’s not. Each number is expressed with three additional zeroes, yet going from a million to a billion requires adding 999 million. Going from a billion to a trillion takes the addition of 999 billion—or, expressed another way, 999,000 million.
It’s not our fault that our brains aren’t wired to contemplate such huge numbers. There’s some evidence from studying Indigenous cultures that human minds intuitively value the relationship between numbers more than the absolute difference between them. For instance, our brains are primed to perceive 1 and 2 as farther apart than 8 and 9 because, relatively, 2 is twice the size of 1, whereas 9 is only 1⁄8 larger than 8. Yet objectively, they are both the same distance apart on the number line.
By the year’s end, the national debt may well reach $41 trillion. Suffice it to say, that’s a really huge number. But then again, so is $40 trillion.
It’s Time to Stand Up for Science
If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.
SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.
If you subscribe to Scientific American, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.
In return, you get essential news, captivating podcasts, brilliant infographics, can’t-miss newsletters, must-watch videos, challenging games, and the science world’s best writing and reporting. You can even gift someone a subscription.
There has never been a more important time for us to stand up and show why science matters. I hope you’ll support us in that mission.
