The Light-Year water bottle
We all know that molecules are small. And that any given substance contains a lot of them. But it can be hard to conceive of how small they are, or how many of them are in something—until you realize that there are so many molecules in just a sine year of water, they’ll stretch out an entire light year!
To be honest, when we were thinking about creating an unusual water bottle for the box, we didn’t realize that was the case. While considering which interesting measurements to put on it, one was “there are x many molecules of water in this bottle.” Not too hard to calculate, and it was a big, impressive number. But so big that it was almost meaningless; a number difficult to visualize in concrete terms. So we thought “well, how far would that much water stretch?” Figuring it would be something big and impressive sounding—five kilometers, maybe, or the height of the Statue of Liberty. Even though a molecule of water is just .27 nanometers long, that distance turned out to be much, long longer. Astronomically longer.
A water molecule is about .27 nanometers long, which interestingly enough, makes it smaller than molecules of oxygen (O2 is .299 nm) and nitrogen (N2 is .305 nm).
So if you calculate how many molecules of water are in a volume of water, then multiply that by the length of each molecule, you find out It takes a little bit more than a liter’s worth for a monomolecular line of water molecules to reach a light year. Depending on how you round out figures for the number of molecules in a liter and the number of nanometers in a light year, it’s between 1,030 and 1,040 milliliters. So in the interests of transparency, the volume is roughly, but not precisely, a liter.
We’ve added several other curious measurements to the bottle, as well:
The volume of water in 4,000 four-leaf clovers
The amount of water that would weigh as much as a human heart
The volume of saliva produced by a human every three hours
The volume of water you lose every night from breathing while asleep
If you’re looking at the scale on the very bottom of the bottle, on the other hand, you’ll see it’s only measuring a tiny amount of liquid; your eyes each contain about 6 mL. The reason that two of the measurement lines on the bottle are curved arcs is because those measurements—1,040 mL for the light year and 12 mL for your eyes—were above and below the ability of manufacturers to print on the bottle, so we figured out the inclination at which you’d need to tilt the bottle to see the proper amount of liquid. Angle the bottle until the water inside is even with the arcs for those two measurements.
That how far a little more than a liter of water will take you. So how much water would you need to get to other extraterrestrial locations?
Proxima Centauri is 4.22 light years away, so not that much—just 4.3 liters, a bit more than the recommended amount of water an adult human is supposed to be drinking on a hot day.
The center of our home galaxy, the Milky Way, is about 26,0000 light years away, so around 27,000 liters. That much water is about what you’d need to fill a large backyard swimming pool.
The Andromeda galaxy is approximately 2.537 million light-years away. How much water would you need to reach it? A little more than 2.6 million liters, the same amount as goes over Niagara Falls every second—or enough to slightly overfill a regular Olympic-size swimming pool (they only hold 2.5 million liters).
The diameter of the observable universe is about 94 billion light years, so to stretch that distance would require around 97.7 billion liters of water. To hold that, you’d need about the same amount of water that flows in all the rivers on Earth in a minute and a half.
The diameter of the observable universe is about 94 billion light years, so to stretch that distance would require around 97.7 billion liters of water. To hold that, you’d need about the same amount of water that flows in all the rivers on Earth in a minute and a half.
