Assertion: comoving distance | /r/HasProperty | denoted \displaystyle \chi
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text: On this usage, comoving and proper distances are numerically equal at the current age of the universe, but will differ in the past and in the future; if the comoving distance to a galaxy is denoted χ {\displaystyle \chi } , the proper distance d ( t ) {\displaystyle d(t)} at an arbitrary time t {\displaystyle t} is simply given by d ( t ) = a ( t ) χ {\displaystyle d(t)=a(t)\chi } where a ( t ) {\displaystyle a(t)} is the scale factor (e.g. Davis & Lineweaver 2004).