How does gravity bend time?
Imagine you are an astronaut who travelled to another planet. A planet where an hour is equivalent to 7 years back on Earth.
This is Miller's planet from the 2014 blockbuster movie Interstellar. The film's black hole was so scientifically detailed that it led to a peer-reviewed paper, published in the journal Classical and Quantum Gravity.
Truth be told, the idea of the film is a real concept called Time Dilation. It's the idea that time may stretch or slow down in stronger gravity. Miller's planet orbited a black hole named Gargantua, a rapidly spinning black hole (spinning nearly at the speed of light!) dragging the fabric of space around it. Consequently, Miller's planet had to revolve around Gargantua at half the speed of light in order to maintain its orbit. This illustrates how time slows down in stronger gravity or at faster velocity.
As shown by Albert Einstein, time is not fixed but relative, based on speed and gravity. His theory of relativity explained that heavy objects like Earth warp the fabric of space and time around them, which we feel as gravity.
The closer you are to a massive object -----> the greater the gravity ----> the slower time runs for the observer
A real-life example we have is of GPS (Global Positioning System) satellites, which are positioned high above Earth where the gravity is weaker, hence their clocks tick faster than the clocks on Earth. They gain about 38 microseconds each day, which is why this difference has to be corrected for. This correction allows the precise planning required for things like airplane landings or navigation. If it wasn't addressed through Einstein's calculations, the navigation maps we use today would've been off by around 10 to 11 kilometres each day.
Hence, time is unique to whoever measures it. It revolves around velocity and gravity while the speed of light remains constant. This understanding of time has helped humanity safely explore the universe.
