Quasar Quest | Beyond Astrophysics on Instagram: "Time travel has a strange rule: if it ever becomes possible in the future, it instantly becomes possible in the past. Because the moment a time machine exists at any point in history, it can appear at every point it decides to visit. The invention doesn’t happen at one moment in time. It ripples backward. This is why physicists say time travel creates loops instead of straight lines. The cause and the effect fold into each other, and the origin d