As a perspective of the vast amount of unknown knowledge and how small a place we occupy in the Universe, consider the following:
http://www.youtube.com/watch?v=fgg2tpUVbXQ
Look up into the night sky, find the darkest place you can find between any two stars. Using the Hubble telescope aimed out into space at just a tiny portion of the blackness between those two stars, many thousands of galaxies can be seen. Move over, just a tiny bit, still between those same two stars, and thousands of different galaxies can still be seen. Between those same two stars there are many thousands of different positions the Hubble telescope can look.
Millions of different galaxies we can see between any two stars. The Hubble telescope can not see between the dark spaces of the galaxies it sees at it's furthest reaches. But imagine what is beyond. Now consider all this lays between only two stars. Just as much, and more exists between all the other stars that you see in the sky and in all directions around the Earth. We can now see more galaxies than there are grains of sand laying on the surface of the Earth.
Within our own Milky Way galaxy, our Sun is only one of over 200 billion other stars. The Universe is at least 15 billion years old. Humans have been around for not more than 4 million years. Only in the last 200 years have we attained what we would consider significant knowledge. Just from what we see, there are 40,000,000,000,000,000,000,000,000 other solars systems that can potentially support life; assuming only 1 in every 1,000 stars can support life at some time during its solar life. Other species have potentially been around many billions of years longer than ourselves.
Knowledge amongst humans grows exponentially. The volume of information doubles every seven years. Assume only one planet for every 1 million planets that can support life, has a human equivalent. Potentially, 2^(10E9/7) * 40E24/1E6 = a multiple of the volume of knowledge we presently know, and a number so great that my calculator can not manipulate the large numbers involved. This represents the vast amount of knowledge in the Universe that existed before humans appeared on the Earth. The amount of information that is potentially available within the Universe is so vast, that we should consider ourselves to be ignorant.
