Please verify if this is a valid approach. If not, please explain why.

As a particle approach the speed of light, its perception of time changes (the "internal clock" slows down).

Everything travels throught space, but also through time. We could even say that the faster something travels through space, slower it does throught time.

Can i discribe the particle's own time by the formula: Vt^2 + Vs^2 = c^2 ?

where:

Vt = speed in time.

Vs = speed in space.

c = speed of light.

this way, for an object to "age" 2x slower (Vt/2) than a rest particle his Vs should be:

Vs = sqrt(c^2 - Vt^2)

Vs = sqrt(c^2 - (c^2)/4)

Vs = sqrt((3/2)*c^2) = sqrt(3)*c/2