Backtracking Upon Space-Time

"Neptune, what happened?"

Normally, Neptune notifies the team in advance before the hull shakes, allowing Gu Ding and Liliath to brace themselves. But when the ship shook this time, Neptune did not give an early warning and both Gu Ding and Liliath nearly fell down. Instead, only Biggie stood steadily on the ground, as if there was a magnetic force between his soles and the floorboard.

"We... seem to have experienced the legendary space-time backtracking ..." Neptune's tone sounded grave.

"What is space-time backtracking?" Gu Ding thought it sounded a bit unpleasant.