It is hard to believe where society would be right now if we did not have such modern and everyday inventions such as the airplane or even something as simple as electricity which is common to every American. If you were a person who lived in the time before the invention of the airplane and someone told you that one-day someone would build a craft that would be able to fly from continent to continent, then what would you think your response would be? It would seem just as much of a challenge, or impossibility, as the modern day problem of finding a cure for cancer or aids. The thing all these have in common is that each challenge has a solution that is just waiting to be found. Nothing is impossible. Throughout time there have been many things people think cannot be done, but then there are going to be people who wont take no for an answer and prove everyone wrong in order to make the impossible possible.
First of all, in our history many people have been proven wrong due to their pessimistic attitude. If someone decided not to test out electricity and explore its uses it is quite possible that we could still be using fire to light our homes. Imagine how far back the world would be if someone didn't decide to give a computer a shot and attempt to make it work. In the future people are going to think that some things are impossible, but it is this attitude that makes them impossible. That is the only way something can truly be impossible. An example is a cure for aids or cancer; some people might right away tell you that this is completely impossible. With this cynical attitude the cure would most definitely be impossible, but there are people who know there is a cure and are willing to go against other peoples ideas of impossibility and are searching for it.
Along the way of trying something that others around you feel is impossible there will always be the people that tell you it can't be done, so it shouldn't be tried.