I love the word "impossible". So many people throw it around, and sadly, even prominent scientists of massive intellect and world renown status even do it. Still, science is an ever progressing system, constantly evolving and changing itself to reflect better data and better analysis. This is why I love it so much.
We don't...well, we shouldn't...ever state that something is final and nothing more can be done. Or that anything is "holy" and unquestionable. LIFE is nothing BUT a series of questions for which we strive to find the answers. Blind faith results in just that...blindness. What was once thought to be impossible can quickly become commonplace is a short amount of time.
Just look at space travel. Kind of mundane now, right? Major news stations cover a Shuttle launch for about 2 minutes and then bugger off to go talk about Lindsey Lohan and her ever present social retardation. Now, go back 200 years and discuss space travel and people would think you're nuts, or a witch! lol. Careful what you say...representatives of God might try to get you.
My point is, whether in science or any other aspect of life, do your best not to throw around the word impossible, because even for great minds like Einstein, that word can come back to bite you in the butt. :)