The biggest thing waiting to be discovered in physics and astronomy is the properties of dark matter (exactly what is it?). Bad astronomy has a post with a summary of the results from WMAP. And the biggest surprise for me was that normal energy and matter are < 5% of the universe. So what, exactly, is the rest of the universe made of? I’m extremely curious about dark matter. The majority of the universe is dark matter and dark energy yet we know virtually nothing about them. It seems spurious for us to speculate on things such as other life in universe when we know almost nothing about what most of the universe is composed of.