"The free-particle dispersion-relation (K vs. p) at anyspeed:" Plots of "kinetic energy" K = mass m × (γ-1)c2 where Lorentz-factor γ ≡ dt/dτ "versus" "momentum" p = h/λ = mass m × proper-velocity w ≡ dx/dτ, for an almost comprehensive range of everyday values along both axesP. Fraundorf (2011/2012) "Path-analysis of metric-first & entropy-first approaches", arXiv:1106.4698 .. Here τ is proper-time elapsed between two events on the world-line of our traveling object, x is the map-distance and t the map-time separating those events, h stands for Planck's constant, and as usual c stands for the space-time conversion-constant also known as lightspeed. Lines of constant coordinate-velocity v ≡ dx/dt on this log-log plot have a slope of 1, while lines of constant rest-mass m well below the "lightspeed curtain" on this plot have a slope of 2.