My relativity book defines the "worldline" of a system as:

\begin{equation} x(\tau)=(x^0(\tau),x^1(\tau),x^2(\tau),x^3(\tau))^T \end{equation}

I often see velocities written in the same form: $U=(0,u^2,0)^T$

What does the "$T$" superscript mean?


The $T$ stands for "transposed". The vectors $x(\tau)$ and $U$ are column vectors, but they are printed as transposed row vectors to save space.

  • $\begingroup$ So that's why the superindex is removed once the vector is expressed as $\begin{pmatrix} x^0(\tau) \\ x^i(\tau) \end{pmatrix}$ $\endgroup$ – IchVerloren Feb 21 at 2:09

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.