People who claim something can't be done are foolish. Claiming a negative - claiming something you can't prove - is anti-intellectual at best, downright ignorant at worst.

There is no need to claim something can't be done. It serves absolutely no purpose. The only possible outcome that negativity can have is to stop someone from trying, when really - thats the heart of scientific discovery. We can't fly, we can't break the sound barrier, we can't we can't we can't.

History is full of people who claim we can't. But history forgets those people, and remembers the ones who actually did.