The Science of Interstellar

This post is a compilation of the cool things I discovered when reading the book The Science of Interstellar by the legndary physicist and Nobel laureate Kip Thorne. In case you haven’t already, watch Interstellar!

• At the event horizon, time comes to a halt and inside the horizon, time flows spatially and the “future” for time is towards the singularity. This explains why nothing escapes the black hole after the event horizon since the future is towards the blackhole and escaping it would mean going back in time. Thus escaping the black hole isn’t prevented by a physical barrier but because it means going back in time.
• Accretion disks : when a star comes close enough to a quasar’s black hole that it is affecetd by the hole’s gravity. This effect leads to the star being torn apart primarily cause the star’s gravity can no longer hold the star’s content together. This gas that is sucked up by the black hole leads to the formation of the accretion disk
• When looking at the accretion disk equitorially from one side of it, we can even see the part of the disk behind the black hole (the disk forms a circle around the black hole). Crazy, isn’t it? We can see stuff behind an absolutely impermeable object. The answer - gravitional lensing!
• To reach from Endurance’s parking spot to Miller’s Planet, the spacecraft needed massive speed changes in the order of magnitude of 100,000 km per second. This is far greater than the most powerful rockets we have currently (and will possibly make in 21st century as per Kip Thorne). What do we do when we can’t create something? We rely on nature and it provides us with gravitational slingshots - using gravity of other objects (planets or black holes) to accelerate or decelerate depending on the direction of travel. NASA uses them - used by Cassini to reach Saturn despite not having enough fuel.
• The planetary orbits in our solar system are elliptic curves - as shown by Newton’s laws of gravity. However, around spinning black holes, the orbit is much more complex - covering the whole spherical region around the central black hole.
• Any object that comes near a black hole is not guaranteed to be sucked in by the black hole. It’s more likely that it orbits. The reason is the angular momentum. When an object comes close to black hole, its momentum would produce centrifugal force stronger than the gravity of the black hole and this would make the object continue on the orbit. Only if the object is headed directly at the black hole will it successfully be pulled inside the hole.
• A realistic way to reach near light speeds - using a black hole binary! The binary is two black holes orbiting each other in a highly elliptical orbit. A rocket can enter the critical orbit of one hole, orbit around it a few times. Then leave this orbit precisely at the time when the black hole is headed directly towards the second one. Now, repeat the process - orbit, circle and escape. This can be done as many times as needed and speed can be increased as much as we want (only remember to leave the orbit when there is a straight line travel to the other hole).