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Equation 56 · Part 1 · The Clock That Comes Back Wrong by Exactly Its Mass

Symbol P^mu

PμPμ=m2c2P^\mu P_\mu=m^2c^2
PμP^\mu

What this part means

PmP^mu is part of the quantity the equation computes from the expression on the right.

Its job in the formula

PmP^mu is part of the quantity the equation computes from the expression on the right.

The passage around this formula

…charge, so relativistic quantum mechanics carries no analogue of the mass superselection rule that follows from the Galilei case [ 1 , 4 ] . Mass in special relativity shows up instead as the ordinary Casimir invariant PμP^\mu PμP_\mu=m2m^2c2c^2 : a quantum number you diagonalize, not a phase a loop leaves behind.

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Learn the underlying idea

An exponent tells how a base is used in multiplication. In x³, x is the base and 3 is the exponent: x³ = x × x × x.

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Sources cited in the surrounding passage

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