Eli5 The scale of 18 quintillion


I recently got into no man’s sky and heard the estimated number of planets (as above) I was floored but felt it’s larger than I’m grasping it and even larger than the way I explain it to others.

I recall from a tiktok or something that if everyone in the world played the game and found a planet 24/7, 365.2425 days, it would take approx 15000 years to find every single planet

Edit: these analogies are super helpful, thank you so much!

Is my time scale accurate also?

In: 25

Imagine that every grain of sand on Earth is a planet. The current estimate for grains of sand is 7.5 quintillion. There are 2.4x as many planets in NMS than grains of sand on our planet.

Assuming a human lives to 100 years they will live for 3,155,695,200 seconds.

Assuming the earth has 7 billion people who will live for those 100 years, that will be 22,089,866,000,000,000,000 seconds.

That number is 22 quintillion.


18 quintillion seconds is longer than the universe has existed.


If you were to travel 18 quintillion centimeters that would be 1,900,000 million lightyears. That is about 20 milky way galaxies edge to edge.

18 quintillion isn’t a lot. I mean, it’s just 1.8 * 10^19.

For comparison, there are 10^40 legal chess positions (and over 10^123 illegal ones).

When you have a seemingly small number of variables, (say 64 squares) and a seemingly small number of possible pieces (16 black and 16 white pieces), it suddenly gets very “big” only when you multiply out all the possibilities.

If your planet can be red, blue, orange, green, or yellow, and be snowy, rainy, or dry, and be big, medium, or small, and so on, it’s pretty easy to come up with 18 quintillion combinations from a seemingly small array of possibilities. The planets are just procedurally generated from this small combination of possible factors, leaving you with a seemingly endless (yet entirely bounded) number of possibilities.

Lets put it this way:

If you started counting seconds from the big bang and continued counting all though the present day and then continue until the sun swallowed the earth, you would only be two third into your first Quintillion of seconds.

Since all the answers here are to imagine something huge and amazing, ive decided to reduce 18 quintillion into something small and boring!

So imagine you have 25x 6-sided dies each with a unique color. This will give you roughly the same amount of possible combinations of numbers and colors as there are planets in no-mans sky. You can keep throwing those dice over and over to forever see a new never before seen result, but you will soon realize that the difference arent that big between throw’s, nothing to get excited about even if every throw we do lands a new combination.

Its the same with the game, there is no need to explore all those quintillion planets just as there are no need to throw that set of dice a quintillion times just to have seen them all 😀