The time dilation factor doesn't get large until you get up to a HIGH percentage of lightspeed. It can be calculated by the Lorentz Factor at the link below.

At .7c, the Lorentz Factor is 1.83, so multiply the "apparent" duration by the Lorentz Factor of 1.83. The duration in realtime, then, would be just under 10 years.

One description of Lorentz polarization occurs in x,y,z or cartesian coord's...If a particle has relativistic velocity in (z) direction only, it is said to have Lorentz spatial invariance in that direction.....while the x,y plane remains a Newtonian or Galilean surface.

The Lorentz Factor is the name of the factor by which time, length, and "relativistic mass" change for an object while that object is moving and is often written (gamma).

The Lorentz Factor is the name of the factor by which time, length, and "relativistic mass" change for an object while that object is moving and is often written (gamma).

Pare Lorentz's birth name is Leonard McTaggart Lorentz.