Equation 32 · Part 1 · The Atlas That Refuses to Close
Symbol rho_M
What this part means
rh is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Its job in the formula
rh is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Full expression→Symbol rho_M→Article meaning
The passage around this formula
has units of length by inspection, angular momentum divided by momentum, and it is built from nothing but the two Poincaré-invariant labels, mass and spin, that every observer agrees on regardless of which chart they read a position off of. It will turn out to be the radius of the region within which every well-behaved chart in this atlas has to stay.
Learn the underlying idea
A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.
Open the illustrated subscripts: which member of a family? guide →
See this notation across published equations →
Sources cited in the article section
These citations provide research context; check each source for the exact claim it supports.