reality is asymmetric. From a page at Wiki QUOTE (Wikipedia.org+) (SNIP) The mass of the neutron and the proton are almost identical: (SNoP) And the proton weighs in at 1.67 2 621 71 (29) × 10−27 kg and the neutron at 1.67 4 927 29 (28) × 10−27kg ......so not only