Learn #greek letters for #physics. Here is rho.

What Does the Chi Rho Symbol Mean? One of the most common Christian symbols in Catholic churches and artwork is the monogram Chi Rho (XP). Chi (χ)and Rho (ρ) are the first two letters of Christ in Greek (ΧΡΙΣΤΟΣ). Therefore, the Chi Rho symbol means Christ. Also, combining the two letters into one gives the symbol a shape similar to the cross. The popularity of Chi Rho Christogram symbol can be traced back to the conversion of the Emperor Constantine. In AD 312 Constantine witnessed a vision of