# Spacetime Reversal Goes Forward

summary:

While space reflections require a mirror, and time reflection need memory, a reflection in both space and time can look the same as no reflection at all!

description:

The input is in yellow, going from (-5 -5 -5 -5) to zero. The space reflection in blue, (-5, 5, 5, 5) to zero, is a mirror operation around the origin. The time reflection, (5, -5, -5 -5) to zero, in green requires you recall how the yellow input collection of events came onto the stage, so the green back it out. The reflection of both time and space, (5, 5, 5, 5) to zero, in red looks like a continuation of the yellow. Deep in quantum field theory they tell the odd tale of antiparticles going backward in time looking like particles going forward in time. Such an animated story now looks more reasonable.

command:
q_graph -dir vp -out spacetime_reversal -loop 0 -box 5 -command 'q_add_n -5 -5 -5 -5 0.005 0.005 0.005 0.005 1000' -color yellow -command 'q_add_n -5 -5 -5 -5 0.005 0.005 0.005 0.005 1000 | q_conj' -color blue -command 'q_add_n -5 -5 -5 -5 0.005 0.005 0.005 0.005 1000 | q_conj | q_x_scalar -1' -color green -command 'q_add_n -5 -5 -5 -5 0.005 0.005 0.005 0.005 1000 | q_x_scalar -1' -color red1
Outside video:
math
equation:

\begin{align*} q\to q' &= q* \quad\textup{space reversal}\\ q\to q' &= -q* \quad\textup{time reversal}\\ q\to q' &= -q \quad \textup{spacetime reversal} \end{align*}

tags
Physics Tag:
space reversal
time reversal
spacetime reversal
Math Tag:
conjugates
conjugates
Programming Tag:
command line quaternions
q_conj
q_x_scalar