Einstein’s general theory of relativity has made some science-fiction films a little less fictional.

Interstellar, a 2014 space-exploration film, relied upon theoretical physics for its premise: a group of astronauts seeks a new planet for humans to inhabit and jumps time and dimensions in the process. LIGO co-founder Kip Thorne served as science consultant and executive producer. With Thorne’s assistance, the film explores some concepts drawn from the science of gravitational waves.

  • Similar to what LIGO is collecting, the astronauts need to collect data from the singularity of black hole in order to “solve gravity.” They’re referring to the calculations of a gravitational constant, called “Big G,” needed to harness sufficient gravitational force to launch a space station containing the human race. The singularity is the point at which objects cannot return from passing through a black hole, and thus time and space are permanently distorted.
  • Interstellar and many other space-travel films forgo the inaccurate warp-drive model made famous by Star Trek, in favor of a wormhole , or a connection between two tears in the fabric of space-time. An immense amount of energy is needed to “fold” the fabric in this way. The astronauts travel through a wormhole created by future humans who knew from their history that they would need to do this to ensure their survival. This is a prime example of a paradox: two events in space-time that depend on each other’s cause, instead of having a logical cause-and-effect.
  • The dark side of time travel is explored as characters undergo relative aging : because gravity makes time move more slowly as it warps space-time, astronauts leaving Earth and approaching a black hole age in an hour while their families on Earth age in years.
  • The film portrays backwards time travel as a function of a tesseract , the four-dimensional version of a cube. This phenomenon occurs as gravity bleeds through dimensions at the singularity of the black hole. The fifth dimension is the immensely compact realm at the singularity that connects the three dimensions of space with the fourth dimension: time. Because of the connection through gravitational waves, the astronaut is able to communicate with someone on Earth in a different time.

Einstein’s general theory of relativity lent itself to the science of the classic Back to the Future films (1985, ’89, ’90), which portray traditional time travel but suggest that human travelers could move to alternate universes to affect reality in their “home” timeline.

  • The general theory of relativity suggests that humans can only travel forward in time, if they were to approach the speed of light. However, quantum mechanics might allow for a being to exist in two states. In that sense, Doc Brown’s DeLorean-turned-timeship doesn’t create a wormhole but instead “jumps streams” because time flows like a river. That’s why it needs to reach a high speed.
  • The flux capacitor stores the energy of the flow of time in order to keep a point of reference so that the DeLorean doesn’t end up in the far reaches of space.
  • When Marty travels back in time, he’s not actually rewinding his past, he’s popping into an alternate reality. The second film demonstrates this by showing Marty and Doc existing in duplicate in this reality.

– by Rachel Wayne