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Understanding the Most Extreme Numbers in the Universe

August 13, 2018


Did you know that there are more stars in our night sky than there are grains of sand on planet Earth? Even more striking: there are more atoms in a single grain of sand than there are stars in the entire universe.


When it comes to planets to galaxies to super-voids more then a billion light years across, size matters. And sometimes, it can feel difficult or impossible to mentally grasp the size of these gigantic things, because humans didn't evolve to think that way. But by taking advantage of the ways our brains map out our environments, we can get around those limits and maybe start to understand certain things, like how far the closest star is.


Lots of animals including humans create mental maps of their environments. As we evolved, our mental maps included things like where resources were, where predators lived, and nearby water sources. These days, your map is probably the reason you can stumble to the bathroom in the middle of the night instead of walking straight into a wall.


But when it comes to areas of our universe, we not only have to grasp the concept of extreme sizes like atoms or solar systems, but also understand their structures.


The number of objects or landmarks between two points changes our understanding of the distance between them. In one study, researchers asked people to look at a page with a bunch of points on it and estimate how far apart they were. What they determined was that people assumed there was more distance between clusters of points versus the distance between single points.


Other experiments have shown that our mental maps of cities - even the ones that we grew up in - work in similar ways. Our understanding of the distance between two points is affected by what's in between. This works really well in a forest or in a city, but is not so good at mapping something like outer space.


In space, most objects are anything but medium-sized, and are separated by huge expenses of nothing - like real, actual nothing. It's too big and too spread out for our brains to comprehend. However, there is something we can do about it.


It seems that accounting for size, structure, and time is a way we can better understand these total extremes.


If we turn the huge numbers into smaller, more understandable units, it helps. For example, take our closest star - Proxima Centauri. 



Proxima Centauri is 4.2 light-years away, meaning that it would take 4.2 years to get there if you were traveling at the speed of light. Most people can understand how long 4.2 years is, but the speed of light - over a billion kilometers (600 million miles) per hour - just registers in our minds as “big number.”


To really comprehend how big that gap is, we need to put all factors together. So if you're having trouble picturing things with huge or tiny measurements, it might help to put them in terms of something more relatable. Then just maybe, a number like a hundred trillion trillion (100,000,000,000,000,000,000,000,000) meters - the diameter of the observable universe - can make a little more sense, like it just so happens to also be the number of human hairs it would take to cover the entire surface of the Earth to a very itchy depth of one meter.


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Sources: This story was originally published on SciShow Space. I am republishing a lightly edited version on SkyFeed in light of interest on the subject. Green, Hank. "Understanding the Most Extreme Numbers in the Universe." SciShow Space, YouTube. 27 Oct, 2015. Web.

Cain, Fraser. "Are There More Grains of Sand Than Stars?" Universe Today. 25 Nov, 2013. Web article.

Citation: Rovira, Lia N. "Understanding the Most Extreme Numbers in the Universe." SkyFeed. 13 Aug, 2018. Web article.

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