We know a lot of things, but what we don't know is a lot more.

1/r^2 has a nasty singularity at r=0, but it did not bother Newton-the Moon is far enough.

I have a much easier time imagining how we would understand the big bang, even though we can't do it yet, than I can imagine understanding consciousness.

There is a difference between knowing what is true and knowing why it is true

You enter a completely new world where things aren't at all what you're used to.

The theory has to be interpreted that extra dimensions beyond the ordinary four dimensions the three spatial dimensions plus time are sufficiently small that they haven't been observed yet.

As far as extra dimensions are concerned, very tiny extra dimensions wouldn't be perceived in everyday life, just as atoms aren't: we see many atoms together but we don't see atoms individually.