Ram pressure and length contraction

In Special Relativity, time dilation comes paired with length contraction, the shortening of a moving object along its direction of travel. RSI gives it a physical cause.

A knot is a standing pattern of waves that travel at c through the medium. When the whole pattern moves, the waves running forward must catch up with a receding edge and those running back meet an approaching one. The pattern holds together only by settling into a new shape: shortened along its motion by exactly √(1 − v²/c²), and unchanged across it. Oliver Heaviside found this in 1889 for the field of a moving electric charge, and George FitzGerald proposed the same shortening for all matter. RSI calls the waves meeting the oncoming medium at the knot's front Ram Pressure.

This is not drag. The Eternal Consonance has no viscosity, and a body moving steadily through an ideal fluid meets no resistance at all, as Jean d'Alembert showed in 1752. That is why uniform motion through the medium cannot be felt. Together with the slowing of the knot's internal rhythm, the shortening hides that motion from every local experiment.