The Science of Interstellar

The other tiny hope for natural wormholes is the big bang creation of the universe. It is conceivable, but very unlikely, that traversable wormholes could have formed in the big bang itself. Conceivable for the simple reason that we don’t understand the big bang well at all. Unlikely because nothing we do know about the big bang gives any hint that traversable wormholes might form there.

Can Wormholes Be Created by an Ultra-Advanced Civilization?

An ultra-advanced civilization is my only serious hope for making traversable wormholes. But it would face huge obstacles, so I’m pessimistic.

One way to make a wormhole, where previously there were none, is to extract it from the quantum foam (if the foam exists), enlarge it to human size or larger, and thread it with exotic matter to hold it open. This seems like a pretty tall order, even for an ultra-advanced civilization, but perhaps only because we don’t understand the quantum gravity laws that control the foam, the extraction, and the earliest stages of enlargement (Chapter 26). Of course, we don’t understand exotic matter very well either.

At first sight, making a wormhole seems easy (Figure 14.8). Just push a piece of our brane (our universe) downward in the bulk to create a thimble, fold our brane around in the bulk, tear a hole in our brane just below the thimble, tear a hole in the thimble itself, and sew the tears together. Just!

^{Fig. 14.8. Creating a wormhole. [Drawing by Matt Zimet based on a sketch by me; from my book Black Holes & Time Warps: Einstein’s Outrageous Legacy.]}

In Interstellar, Romilly demonstrates the same thing with a sheet of paper and a pencil (Figure 14.9). As easy as this may look from the outside, playing with pencils and paper, it is horrendously daunting when the sheet is our brane and these manipulations must be carried out from within the brane, by a civilization that lives in our brane. In fact, I have no idea how to execute any of these maneuvers from inside our brane except the first, creating a thimble in our brane (which requires only a very dense mass, such as a neutron star). Moreover, if it is possible at all to tear holes in our brane, it can only be done with the help of the laws of quantum gravity. Einstein’s relativistic laws forbid tearing our brane, so the only hope is to make the tear where his laws fail, in a realm of quantum gravity. We then are back to the domain of terra almost incognita (Figure 3.2).

^{Fig. 14.9. Romilly explaining wormholes. Left: He bends a sheet of paper. Right: He punches a pencil (the wormhole) through the paper, joining its two edges. [From Interstellar, used courtesy of Warner Bros. Entertainment Inc.]}

The Bottom Line

I doubt the laws of physics permit traversable wormholes, but this may be pure prejudice. I could be wrong. If they can exist, I doubt very much that they can form naturally in the astrophysical universe. My only real hope for forming them is artificially, in the hands of an ultra-advanced civilization. But we are extremely ignorant of how such a civilization could do it. And it appears more than daunting, at least from inside our brane (our universe), even for the most advanced of civilizations.

In Interstellar, however, the wormhole is thought to have been made, held open, and placed near Saturn by a civilization that lives in the bulk, a civilization whose beings have four space dimensions, like the bulk.

This is terra extremely incognita. Nevertheless, I discuss bulk beings in Chapter 22. In the meantime let’s talk about the wormhole in Interstellar.

15 Visualizing Interstellar ’s Wormhole

The wormhole in Interstellar is thought to have been constructed by an ultra-advanced civilization, most likely one that lives in the bulk. In this spirit, when laying foundations for visualizing Interstellar’s wormhole, Oliver James[28] and I pretended we were ultra-advanced engineers. We assumed that wormholes are allowed by the laws of physics. We assumed the wormhole’s builders had all the exotic matter they needed to hold the wormhole open. We assumed the builders could warp space and time in whatever way we wished them to, inside and around the wormhole. These are pretty extreme assumptions, so I labeled this chapter for speculation.

The Wormhole’s Gravity and Time Warping