18. Black Holes and Extreme Time Travel
If astronauts ventured close to a black hole, they’d encounter the most dramatic form of time dilation imaginable. Near a black hole’s event horizon, gravity is so intense that time can slow to a near standstill compared to distant observers. While this scenario is far beyond current spaceflight, it’s rooted in the same principles that govern astronaut time travel—just taken to cosmic extremes. Read more at NASA.