At tremendous precision, the proton and antiproton still seem identical. Using a novel two-particle measurement method, a group of researchers measured the magnetic moment of the antiproton at a precision 350 times higher than any previous measurement. The result shows that the magnetic moments of the proton and antiproton are tremendously close, meaning that so-called CPT asymmetry -- a key factor in the lack of antimatter -- must be very small if it exists at all. Source 2g.