The Science of Interstellar

The result is the same: lander 1, piloted by TARS, and Ranger 2, piloted by Cooper, fire their rockets while attached to the Endurance, pushing the Endurance back out of Gargantua’s gravitational grip. Then, to get the last possible kick, explosive bolts blow the Endurance apart from lander 1 and Ranger 2. The lander and Ranger go plunging downward toward Gargantua, carrying TARS and Cooper with them, and the Endurance is saved (Figures 27.7 and 27.8).

In the movie, there is a tragic, parting conversation between Brand and Cooper. Brand doesn’t understand why Cooper and TARS must accompany the lander and Ranger into the black hole. Cooper gives her a rather lame though poetic excuse: “Newton’s third law. The only way humans have ever figured out for getting somewhere is to leave something behind.”

^{Fig. 27.7. The Endurance is thrown back up to the critical orbit by firing of rockets, followed by ejection of lander 1 and Ranger 2. [Image of the Endurance is from Interstellar.]}

^{Fig. 27.8. Ranger 2 descending toward Gargantua, as seen by Brand in the Endurance, with portions of two Endurance modules in the foreground. The Ranger is the faintly seen object in the picture’s lower center, surrounded by Gargantua’s accretion disk. [From Interstellar, used courtesy of Warner Bros. Entertainment Inc.]}

This surely is true. But the additional thrust on the Endurance, from Cooper and TARS accompanying the lander and Ranger into the hole, is awfully small. The greater truth, of course, is that Cooper wants to go into Gargantua. He hopes that he and TARS can learn the quantum gravity laws from a singularity inside Gargantua, and somehow transmit them back to Earth. It is his last, desperate hope for saving all of humanity.

The Endurance’s Launch Toward Edmunds’ Planet

The critical orbit is an ideal spot for Brand and the robot Case to launch the Endurance in any desired direction, in particular, toward Edmunds’ planet.

How do they control their launch direction? Because the critical orbit is so unstable, a small rocket blast is sufficient to send the Endurance off it. And if the blast is ignited at precisely the right location along the critical orbit and has precisely the right strength, it will send the Endurance in precisely the desired direction (Figure 27.9).

^{Fig. 27.9. The Endurance’s trajectory off the critical orbit, toward Edmunds’ planet. [Image of the Endurance is from Interstellar.]}

Actually, Figure 27.9 may leave you unconvinced that Brand and Case can launch in any direction they wish. That’s because it doesn’t capture the critical orbit’s three-dimensional structure. For that, see Figure 27.10.

^{Fig. 27.10. A three-dimensional picture of the Endurance’s critical orbit and its launch toward Edmunds’ planet. The critical orbit wraps around a sphere that surrounds Gargantua.}

This convoluted critical orbit is a close analog of the trajectories of temporarily trapped light rays inside Gargantua’s shell of fire (Figures 6.5 and 8.2). Like those light rays, the Endurance is temporarily trapped when on its critical orbit. Unlike the light rays, the Endurance has a control system and rockets, so its launch off the critical orbit is in Brand’s and Case’s hands. And because of the orbit’s convoluted three-dimensional structure, the launch can be in any direction they wish.

But their launch leaves behind Cooper and TARS, plunging through Gargantua’s horizon. Plunging toward Gargantua’s singularities.

28 Into Gargantua

Some Personal History

In 1985, when Carl Sagan wanted to send his heroine, Eleanore Arroway (Jodie Foster), through a black hole to the star Vega, I told him NO! Inside a black hole she will die. The singularity in the hole’s core will tear her apart, chaotically and painfully. I suggested he send Dr. Arroway through a wormhole instead (Chapter 14).

In 2013, I encouraged Christopher Nolan to send Cooper into the black hole Gargantua.

So what happened in the quarter century between 1985 and 2013? Why did my attitude toward falling into a black hole change so dramatically?