Dear Ella --
"Why does everything need water to live? Is there anything alive that doesn't need water?" These are great questions! We don't know the answers! There are people who ask these questions every day when they go to work. These people are scientists. They look very closely at the tiniest pieces of animals and plants, to see what the tiniest pieces of water do. And there are other scientists who look at animals and plants that live in places where there is very little water, to see how those animals and plants can live with only small amounts of water. And still other scientists think about how things might live where there isn't any water at all.
I need to make sure you know some things first, so that I can use some words and know that you know what I mean.
"What is stuff made of?"
You may already know about solids, liquids, and gasses, but if you don't, here we go. Most of the stuff we know about, the stuff that you and I and all our friends and animals and plants and rocks and air and all those things are made of Matter. Water is made of matter. And water can be made into ice in the freezer, and it can be lost in the air, too, like when you puff out a breath on a cold day. You can see the water for a little bit before it gets lost in the air. When water is ice, we call it a Solid. When water is regular water like you drink or swim in, we call it a Liquid. When water disappears into the air, we call it a Gas. So there is solid water (ice), liquid water (water), and gas water (part of the air).
Two more things you need to know. Matter, all of the stuff we know of, is made of tiny pieces. We call those tiny pieces Atoms, which means “tiny pieces of stuff that can’t be broken into smaller pieces.” Lots of atoms like to stick to other atoms, like little kids who have a stuffed animal that they won’t let go of. When atoms are stuck to other atoms, we call them Molecules, which is a fancy word for a group of atoms all stuck together. Water is made of three atoms stuck together, so the tiniest pieces of water are things we call Water Molecules.
OK, here we go now with answering your questions:
"Why does everything need water to live?”
All living things that we know about need liquid water to live. Liquid water is good because it can carry things in to you, like noodles in soup, and out of you, like when you pee, so you can live. And liquid water is good because it lets solid things slip on each other, like your eyelid sliding over your eyeball. And liquid water is good because the water molecules help lots of other molecules do all the things that you need to do to stay alive. We are still finding out about how water molecules help other molecules in your body. It is very complicated, and very very interesting. If you wanted to, you could learn about what water molecules do in our bodies, and then get a job finding out new things about that. Then you would be a scientist.
“Is there anything alive that doesn't need water?"
We really don't know, because we don't know of anything alive in a place where there isn't any water. That is mostly because there is water on Earth, so everywhere we can look to see if there is something alive, we also find water.
“Where else can we look for life, besides on Earth?”
We send robots to Mars to look for life there. We look for water, because we know if we find that there was water, that there could have been things alive. Just in the last couple of years, we found that there used to be lots and lots of water on Mars. So if we find out that there used to be things living on Mars, we can understand that, because there used to be water.
“Where else can we look, besides Mars?”
Saturn has a moon, like Earth has a Moon, only Saturn's moon is bigger. We call it Titan. We sent a robot to Titan, to find out what Titan is made of. Titan has oceans, and rain, and clouds, and fog, all things that water does on Earth, but Titan is too cold, so all the water is solid. Titan is made up mostly of solid water, which is the same thing as ice. But the robot found liquids on Titan! So if it is too cold for liquid water, it must be something else.
“What are the liquids on Titan?”
On Earth, we have wine and beer and other things that adults like to drink that have Alcohol, and water, in them. The oceans and clouds on Titan are made of alcohol. So you can imagine that Titan is covered with wine or beer, but without the water part.
“So is there life on Titan that doesn’t need water to live?”
We don’t know. We sent one robot to Titan. It landed in one place, measured some things about light and alcohol, and that’s it. We need to send more robots to find out. Some scientists are making plans to send a robot sail boat, to sail around the seas of Titan, looking for life. But at this point we don’t know if there is any life there.
So if you want to know if there is life that does not need water, learn everything you can about life and water and math and science while you are in school, and imagine your own robot that can go to Titan to look for life in the alcohol seas there. Or imagine how to make a place on Earth that really has no water, and try to get some things to live there. Dream of ideas, and then dream of finding out, and then go and find out for yourself!
Much love,
Paul
