Speaking to a theater full of curious physicists, engineers, and students, Jonathan Nolan quietly let slip that his original ending to Interstellar was “much more straightforward.”

Yesterday in Pasadena, California, as a part of a media event surrounding the impending Blu-ray release of the sci-fi blockbuster Interstellar, co-writer Jonathan Nolan and science adviser/producer Kip Thorne addressed a packed theater at Caltech’s Jet Propulsion Lab (JPL). After going though much of the science of the film, the floor was opened to questions. One of the first was probably the one on everyone’s mind: What actually happened at the end of Interstellar?

“You’ve got the wrong brother,” Nolan quipped.

At the end of the film [SPOILERS], we see Matthew McConaughey’s character jettison himself into the singularity of the black hole Gargantua. He makes the deadly journey in the hopes of characterizing gravity acting at the smallest scales inside, and to send that data back to Earth. He survives the descent, but then finds himself inside a 5th-dimensional “tesseract,” which he uses to peruse the timeline of his life and contact his daughter’s younger self.

That’s the ending that has had audiences and scientists alike scratching their heads. I have my own (probably incorrect) theory of what the heck happened, but I was eager to hear it directly from the script’s original writer.

Jonathan Nolan’s much more straight-forward ending “had the Einstien-Rosen bridge [colloquially, a wormhole] collapse when Cooper tries to send the data back.”

So no tesseract (that was Christopher’s idea), no time manipulation, and no return home. Nolan didn’t elaborate on this point, but we might speculate that the original end to the movie was as dark and unforgiving as space.

If the wormhole collapses, that means there is no way for Cooper to get home (though the data maybe made it back to help the dying Earth), no way to find Anne Hathaway’s character, and likely a one-way trip into a black hole. It would be a classic hero’s sacrifice, which admittedly bends fewer physical laws than gravity waves ripping across worldlines embedded in a 5th-dimensional cube by some “bulk beings.”

That wasn’t the only major change from the script’s initial drafts. The gravitational anomalies that pointed Cooper and his daughter toward the remnants of NASA were initially supposed to be gravity waves emanating from the destruction of a neutron star via black hole. Since the waves could only be produced by something so catastrophic, and we know nothing like that exists in our solar system, the waves detected must be coming out of some wormhole close to us, Kip Thorne explained to the audience.

The waves were also supposed to be detected by the Laser Interferometer Gravity-Wave Observatory or LIGO, the construction of which Kip Thorne spearheaded. “That was very near and dear to me,” Thorne said, “but Chris thought it was too much science for the public to digest at once.”

Despite these compromises, at least the Interstellar remained accurate enough to generate scientific papers. Alright^3.