Quantum Gravity's Tangled Time (IMAGE) University of Vienna Caption A pair of federation spaceships is performing an exercise near a planet. They are ordered to fire phasers at each other at specific times according to their on-board instruments, and to start engines to dodge each other's beams. The powerful Q decides to play a "joke" on them and uses the planet's gravitational field to change the relative ticking rates of the clocks on the two ships. By placing the planet closer to one of the ships, Q will cause the other one to fire earlier and shoot down the first ship before its instruments show the specified time. Which ship will be destroyed depends on where the planet is placed, as shown by the colour coding in the picture. If Q decides to prepare and measure the planet in superposition of these two places, he will create a superposition of either ship being destroyed. While the two ships can't escape their fate, a subsequent inquiry can confirm that they were indeed in a superposition of two different temporal orders. A quantum test can then reveal that the order of events -- who shot first and who got shot -- is genuinely quantum mechanical, identifying Q as the culprit. Credit Graphic: Magdalena Zych Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.