Clarke's First Law: When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.

Clarke's Second Law: The only way of discovering the limits of the possible is to venture a little way past them into the impossible.

And what is impossible to science?

Another argument of hope may be drawn from this–that some of the inventions already known are such as before they were discovered it could hardly have entered any man's head to think of; they would have been simply set aside as impossible. For in conjecturing what may be men set before them the example of what has been, and divine of the new with an imagination preoccupied and colored by the old; which way of forming opinions is very fallacious, for streams that are drawn from the springheads of nature do not always run in the old channels.

But by far the greatest obstacle to the progress of science and to the undertaking of new tasks and provinces therein is found in this–that men despair and think things impossible.

Flight by machines heavier than air is unpractical and insignificant, if not utterly impossible.

In the world of human thought generally, and in physical science particularly, the most important and fruitful concepts are those to which it is impossible to attach a well-defined meaning.

It is impossible to travel faster than light, and certainly not desirable, as one's hat keeps blowing off.

Most of the crackpot papers which are submitted to The Physical Review are rejected, not because it is impossible to understand them, but because it is possible. Those which are impossible to understand are usually published. When the great innovation appears, it will almost certainly be in a muddled, incomplete and confusing form. To the discoverer himself it will be only half-understood; to everybody else it will be a mystery. For any speculation which does not at first glance look crazy, there is no hope.

Now any dogma, based primarily on faith and emotionalism, is a dangerous weapon to use on others, since it is almost impossible to guarantee that the weapon will never be turned on the user.

Some say that science dictates, or at least its old rules said, that it is impossible for bumblebees to fly. This may be a myth, but wouldn't you like to think that every time you look at the bees, you are seeing that there is no such thing as the impossible?

The Wright brothers flew right through the smoke screen of impossibility.

Their minds sang with the ecstatic knowledge that either what they were doing was completely and utterly and totally impossible or that physics had a lot of catching up to do.

There are also two kinds of truths, those of reasoning and those of fact. Truths of reasoning are necessary and their opposite is impossible: truths of fact are contingent and their opposite is possible. When a truth is necessary, reason can be found by analysis, resolving it into more simple ideas and truths, until we come to those which are primary.

What [man landing on the moon] is doing up there is indulging his obsession with the impossible. The impossible infuriates and tantalizes him. Show him an impossible job and he will reduce it to a possibility so trite that eventually it bores him.

[In Adelie Land, Antarctica, a howling river of] wind, 50 miles wide, blows off the plateau, month in and month out, at an average velocity of 50 m.p.h. As a source of power this compares favorably with 6,000 tons of water falling every second over Niagara Falls. I will not further anticipate some H. G. Wells of the future who will ring the antarctic with power-producing windmills; but the winds of the Antarctic have to be felt to be believed, and nothing is quite impossible to physicists and engineers.