relativistic energy relativistic momentum contravariant four-momentum energy momentum
The relativistic energy 



E
=
γ
(
v
)
m

c

2




{\displaystyle E=\gamma (v)mc^{2}}

 and relativistic momentum 




p

=
γ
(
v
)
m

v



{\displaystyle \mathbf {p} =\gamma (v)m\mathbf {v} }

 of an object are respectively the timelike and spacelike components of a contravariant four-momentum vector:
