This one is always fascinating for me to think about: > There is considerable speculation as to why the observable universe is apparently almost entirely matte

This one is always fascinating for me to think about: > There is considerable speculation as to why the observable universe is apparently almost entirely matter, whether there exist other places that are almost entirely antimatter instead, and what might be possible if antimatter could be harnessed, but at this time the apparent asymmetry of matter and antimatter in the visible universe is one of the greatest unsolved problems in physics. http://en.wikipedia.org/wiki/Antimatter http://en.wikipedia.org/wiki/Antimatter