Let (1,2,3,4) be a 4-vector, in the book's notation, in a stationary frame of reference. Then, in a frame of reference moving with v=0.6c in the negative x-direction, this 4-vector has components (2.750, 3.250, 3, 4) (1.750, -0.250, 3, 4) (-O.250,1.750, 3, 4) (3.250, 2150,14) lpoint Consider the followingfour numbers, all describing the same object (say, a small box): (temperature, length, width, height). Does it make sense to think of these four numbers as a four vector? No. These four numbers will not follow the Lorentz Transform equations when we change frames of reference. Almost. You just need to multiply temperature by some constant so that it has the units of length. Yes, any four numbers can be a 4-vector. No, but in a different order it would work