The Science of Interstellar

In the Prologue of Black Holes & Time Warps (Thorne 1994), I describe, in much greater detail than here, what it would look like and feel like to fall through a black hole’s horizon, both as seen and felt by the infalling person and as seen by someone else outside the black hole. And I describe how the look and feel are influenced by the mass of the black hole and by its spin.

Andrew Hamilton has constructed a “Black Hole Flight Simulator” for computing what it looks like to fall into a nonspinning black hole. His computations are similar to those done for Interstellar by Paul Franklin’s team (Chapters 8, 9, and 15), but preceded Interstellar by many years. Andrew has used his simulator to produce a remarkable set of film clips that can be found on his website, http://jila.colorado.edu/~ajsh/insidebh, and in planetariums around the world (see http://www.spitzinc.com/fulldome_shows/show_blackholes).

Andrew’s film clips differ from what we see in Interstellar in several ways: First, for pedagogical purposes Andrew sometimes paints a grid of lines on the black hole’s horizon (there is no such grid for real black holes and none in Interstellar), and when he does so, he also replaces the star that imploded to form the black hole by a “past horizon.”[59] Second, in his “Journey into a Realistic Black Hole,” http://jila.colorado.edu/~ajsh/insidebh/realistic.html, Andrew endows the hole with a jet and an accretion disk. Gas from the disk falls into and through the horizon, and that infalling gas dominates what the camera sees at and beneath the horizon. In Interstellar, by contrast, there is no jet, and the accretion disk is so anemic that it is not currently sending any of its gas into and through the horizon, so the hole’s interior looks rather dark. However, in Interstellar Cooper encounters a dim fog of light and white flakes from stuff that fell in before him. These are not the result of simulations, but instead were put in by hand by the Double Negative artists.

Chapter 29. The Tesseract

When Christopher Nolan told me he was going to use a tesseract in Interstellar, I was delighted. At age thirteen I read about tesseracts in Chapter 4 of George Gamow’s marvelous book One, Two, Three, …Infinity (Gamow 1947), and that had a major role in making me want to become a theoretical physicist. You can find a detailed discussion of tesseracts in The Visual Guide to Extra Dimensions (McMullen 2008). Christopher Nolan’s complexified tesseract is unique; there is not yet any public discussion of it anywhere, except in this book and others connected to the movie Interstellar.

In Madeleine L’Engle’s classic science fantasy novel for children, A Wrinkle in Time (L’Engle 1962), children travel via a tesseract—they “tesser”—to find their father. My own interpretation of this is a journey through the bulk, riding in the face of a tesseract, like my interpretation of Cooper’s trip from Gargantua’s core to Murph’s bedroom, Figure 29.4.

Chapter 30. Messaging the Past

For physicists’ current understanding of backward time travel in four spacetime dimensions without a bulk, see the last chapter of Black Holes & Time Warps (Thorne 1994), the chapters by Hawking, Novikov, and me in The Future of Spacetime (Hawking et al. 2002), and Time Travel and Warp Drives (Everett and Roman 2012). These are all by physicists who have contributed in major ways to the theory of time travel. For a historical account of modern research on time travel, see The New Time Travelers: A Journey to the Frontiers of Physics (Toomey 2007). For a comprehensive discussion of time travel in physics, in metaphysics, and in science fiction, see Time Machines: Time Travel in Physics, Metaphysics and Science Fiction (Nahin 1999). From Eternity to Here: The Quest for The Ultimate Theory of Time (Carroll 2011) is a wonderful discussion of almost everything physicists know, or speculate, about the nature of time.

I don’t know any good books or articles, for general readers, about time travel when our universe is a brane that lives in a higher dimensional bulk; but as I discuss in Chapter 30, Einstein’s laws extended to higher dimensions give basically the same predictions as without a bulk.

For some technical details of Cooper’s sending messages backward in time to Murph, see the appendix Some Technical Notes.

Chapter 31. Lifting Colonies off Earth