"Tau Zero" was Rob Tow's nom-de-infosphere on the The Well back when it was a dialup BBS system. When he teamed up with Brenda Laurel it became their shared domain name. It is drawn from the title of the novel Tau Zero by Poul Andersen (with his approval) and the original Norwegian spelling of Rob's last name (Tau).

In relativity physics, the "tau factor" is the inverse logarithm of the Lorenz-Fitzgerald contraction as an observer accelerates towards the  speed of light; the tau factor starts at zero at rest, and becomes infinity at light speed.

The logo Rob designed plays on this visually; the triangles are the physicist's symbol for change, here tilted on the side and forshortened from left to right, following the direction shown by the arrow below, indicating acceleration - in Special Relativity, as one goes faster and faster, one shortens in the direction of travel, as seen by an external observer. The colors, changing from red to blue, show the sort of blue shift of the external universe as seen as one accelerates to light speed. When light speed is reached, the deltas become infinitely thin, blue shifts beyond the visible through x-rays and gammas towards infinite energy, mass becomes infinite, and time freezes.