“To the untrained ear, deep into your blog, it begins to sound like fiction. I trust it is all solid science, but I could swear you are making some of those things up from whole cloth.” – an old friend, reading my most recent posts in Out There.
Illustration of a black hole pulling gas from a nearby star--the kind of science that pushes against the limits of human reason. Image (Credit: NASA E/PO, Sonoma State University, Aurore Simonnet) There is a notion in robotics and computer animation known as the “Uncanny Valley.” It describes the unsettling feeling that people get when they look at a simulated person who looks almost—yet not quite fully—real. (The term originated with a Japanese roboticist named Masahiro Mori, who described that sensation in a classic 1970 essay.) The classic pop-culture example is the 2004 movie version of The Polar Express, in which the characters have a realistic but weirdly waxy quality that is far more disturbing than if they explicitly looked like pencil sketches or plastic toys. While Hollywood animators work laboriously to avoid evoking that unpleasant sensation of the Uncanny Valley, the scientists who are trying to decode the fundamental workings of the universe face an opposite challenge. Call it the “Uncanny Chasm”: Modern science is plagued by ideas that seem believable on the surface but that, at a deeper level, seem contrary to our hard-wired common sense. The problem is especially acute in cosmology, where many of the core ideas stray so far from human experience that people tend to accept them merely on the grounds of scientific authority. Black holes that fold space and time in on themselves? Sure, if that’s what the boffins are talking about. Neutrinos from the sun streaming through your body at the speed of light? Invisible energy, woven into the fabric of space, that is causing the expansion of the universe to accelerate? OK, whatever you say, Einstein. But just as moviegoers only half-accepted the characters in The Polar Express, I suspect that they likewise only half-accept these wild astrophysical entities, and walk away with a similar sense of discomfort. A recent email from an old friend of mine—the one I quoted up above—bolsters that suspicion. It was her reaction to my description of a strange set of animal-shaped astrophysical objects, but it could just as well have been a response to almost any new piece of research from cosmology’s deep end. And although this is only one person’s reaction, it matches what I’ve heard from many others, both in person and in emails to DISCOVER over the years. People pay lip service to ideas from across the Uncanny Chasm, but they have a hard time believing. Who can blame them, really? Our hominid brains evolved to solve a very modest and well-defined set of problems unfolding over a fairly limited range of African habitats: find a sustaining diet of meat and plants, escape predators, find shelter, find mates, defend our young, defend our families or social groups from competitors. Amazingly, we evolved the ability to anticipate the future, to calculate different possibilities, and to have self-awareness about our actions. Even so, there is nothing in our historical experience to prepare us for distances measured in light years, time measured in billions of years, or phenomena operating on subatomic scales that are utterly invisible to us. You don’t have to look very far for cosmic news stories that blow way past our mental capacities and put us face to face with the Uncanny Chasm. Let’s pick, almost at random, an intriguing one that just crossed my desk. Researchers working with NASA’s Chandra x-ray observatory studied a colorful glowing cloud of ionized gas known as W49B, located 26,000 light years (about 150 quadrillion miles) from Earth. This cloud is the remnant of a supernova explosion--the detonation of a star at least 10 times as massive as the sun that exhausted the fuel in its core, collapsed, and then detonated catastrophically. Laura Lopez of MIT and her colleagues used x-ray observations from Chandra to trace the mix of elements in W49B, and found that the cloud’s composition is highly asymmetric. Its shape is highly lopsided as well. Lopez believes that W49B formed from an unusual kind of supernova in which much of the explosion occurred along twin jets aligned with the star’s poles, traveling at thousands of miles per secnd. Even more intriguing, there is no trace of a stellar remnant at the center of the cloud. Lopez therefore suspects it collapsed invisibly into a blackhole. Since W49B formed only about 1,000 years ago as seen from Earth, this could make its black hole the youngest one in our galaxy, the Milky Way. This is all fairly uncontroversial science. But what happens when you back and really think about it? When I do that, I run right into the Uncanny Chasm. The distances, masses, and velocities are unfathomable. The research was conducted through studies of x-rays, invisible to human eyes. The models of how a supernova forms and evolves are carried out on supercomputers, because they are far too complicated and time-consuming for humans to explore. The whole narrative of what happened here—a massive star, a riot of nuclear fusion, an explosion, a gas cloud seeded with new elements, a black hole lurking at the center—teeters in that strange area between amazed belief and amazed disbelief. With the Uncanny Valley, there is a solution: make better animation, make more realistic robots, or simply stop trying to simulate the human form. With the Uncanny Chasm, there is no solution. All we can do is work the limits of our brains to take in the wonders of the universe, and marvel that our little three-pound pack of neurons has the capacity at all to make sense of things so much grander than ourselves.