how do u knw air exist? plz answer dis coz i waz waitting for answer sinces i waz 6 yrz old . i ve asked a lot of

Question: how do u knw air exist? plz answer dis coz i waz waitting for answer sinces i waz 6 yrz old . i ve asked a lot of people but i all awyz wanted a scienctific answer plzzzzzzz answer it . thx u. xox
- Keywords:
  air,
  atmosphere,
  exist
Asked by queenofscience to Dalya, Derek, Sarah, Tim, Tom on 19 Jun 2011.
- Dalya Soond answered on 15 Jun 2011:
  
  Love this question since it points out the difference between what we take for granted that we know and what we can prove, and also because it shows you are thinking about the science that surrounds you daily. Not sure I can give you a satisfactory answer, but hang in there. I wanted to see a geyser since I was 6 because I didn’t believe they really existed, and I had to wait nearly 30 yrs but then I finally saw one. They’re AMAZING!
  
  In science, we often take something away to see if it has an effect. What effects would you predict Queenofscience if you took away air, like in a vacuum or in outer space?
  There would be a difference in pressure, and this pressure difference can be measured with tools. So air must exist…or at least what we hypothesise is air exists. Living creatures would also suffocate due to the lack of oxygen (for animals) or carbon dioxide (for plants) so again, air would have a measurable effect. We can also isolate air and measure what it is made of.
  
  Essentially, you can know something exists if you can measure it and can rule out any alternative explanations for your measurements. People have done many measurements on air, but I don’t know if there real reason was to see if it existed. Some of the best and most interesting science comes because a person decides to investigate something they took for granted.
- Sarah Thomas answered on 15 Jun 2011:
  
  There’s a couple of simple experiments that you can do to prove that air exists.
  
  If you light a candle in a room, it will burn and you will see a flame for a few hours until the wick burns out. If you light a candle and put a glass beaker over the top of it, very soon you will see the flame going out. This proves that oxygen exists in the air around us.
  
  Now we can prove that air exists, because if you fill a basin with water, and then take an empty beaker and turn it upside down, and you put it in the water, it will not fill up because the air is trapped inside it. And then if you turn it over underneath the water, the air will come out and rise to the surface of the water as big bubbles and then the beaker will fill with water. So that’s how you can show that air physically exists!
  
  Not very scientific experiments I guess! But hopefully you see what I mean. 🙂
- Derek McKay-Bukowski answered on 15 Jun 2011:
  
  A great question!
  
  There are lots of experiments for this. I like the ones that the others have suggested. Additionally, and this is perhaps the most simplest of all, if you blow on your hand, you can feel it!
  
  However, there are some other experiments.
  
  In the old days, when scientists still weren’t quite sure about it, there were various famous experiments done by Joseph Boyle. In one, he put a bird in a container and pumped the air out. Without the air, the bird started to suffocate. There is a famous painting of this experiment.
  
  I once saw another interesting experiment. Here there was a flask of liquid nitrogen. In it, there was a test tube. Then, using a rubber hose, oxygen was blown into the test tube. The test tube was very cold due to the liquid nitrogen. But because oxygen condenses at a warmer temperature than nitrogen, the new oxygen being blown in started to condense. Oxygen, when liquid is pale blue (a beautiful colour). Basically I could see air being condensed in front of my eyes!
- Tim Millar answered on 15 Jun 2011:
  
  Wind is the molecules in the air moving about so we can see its effects. We can also seperate the air into the gases that make it up and test them. Without it, we would be in a pretty bad state but thats not really a proof.
  
  We know our planet has an atmosphere and we can see how far it extends from space or detect when it runs out using weather balloons and instruments which measure its effects.
- Tom Crick answered on 19 Jun 2011:
  
  Hopefully by the fact that you are alive and breathing in air as we speak! Since animals require air to survive, that should be a clear experimental observation (but not necessarily a proof).
  
  You can do experiments to show what air is composed of (nitrogen, oxygen, etc), you can also do experiments to remove air from a specific area and see what is different. You could also use Brownian motion to show that something moves a smell around a room (or a colour in a clear liquid) by random collisions.
  
  How else do you think we can show air exists?