Hi everyone. I'm almost done with my senior year of university (and will be going to Davis in the fall for the Ph.D. program), and something occurred to me yesterday: the number 3 is very prevalent in our universe. So my question is "Why?" A few examples: As far as we can tell, there are only three families of quarks As above, we think there are only three species of leptons Three color charges Three spatial dimensions The fact that cross-products work (a consequence of three spatial dimensions - cross product is only defined in three dimensions) So I'm sure there are more, but these were the only ones I could think of off the bat (at least, the ones that are interesting and not just numerology). Now, I came to thinking about this because, it just happens that as a mathematical quick, when performing rotations in 3-space, to entirely parametrize the transformation, you need three rotation angles (Euler angles). This is simply because 3 choose 2 is 3 (a "quirk" of the mathematics) - it turns out that there are exactly three distinct planes in 3-space, which leads to 3 distinct rotation angles. In 2-space, there is only one plane, so we require only one rotation angle. In 4-space, there are six planes, so we require six rotation angles. So, is it possible that the fact that there are exactly three color charges, families of quarks/leptons, etc. is simply a result of such a mathematical quark that is a consequence of combinatorics? Maybe this is all a coincidence and I am thinking too much into it. Or maybe we can explain the prevalence of the number 3 by using the anthropic argument. I'd like to hear your thoughts on this.