Particle cosmologist Luna Zagorac reflects on scientific sleight of mind.
“It's still magic even if you know how it's done.” - Terry Pratchett, A Hat Full of Sky
For every child amazed to see a rabbit pulled from a hat, there is a slightly older child slumping in disappointment upon learning of the secret trap door that makes the trick work.
With knowledge of a magic trick’s secret, the spell is broken; instead of invoking wonder, the rabbit-and-hat routine then invokes a sense of being duped, or at least being left in the dark. This is why magicians never reveal their secrets – the illusion, not the technique, is where the magic lies. The more people know the secret, the less magical the trick seems.
The magic of nature, however, casts a different kind of spell. Because nature deals in magic that is true, understanding the secrets of nature’s wonders does not diminish the magic – it enhances the wonder.
Take, for example, an apparatus even simpler than a magician’s top hat: a wall with two narrow slits through which light can be shined. The classic double-slit experiment, a staple of every undergraduate course in quantum mechanics, famously demonstrates the wave-particle duality of quantum physics; light behaves as both a particle and a wave in a way that seems more magical than logical. This seems at first counterintuitive to the point of absurdity – surely being two things at once is some kind of magic.
Before scientists started dabbling in quantum, so-called “classical mechanics” did (and still does) an excellent job of describing the meso scale of physics — phenomena that are not tiny and not huge, but rather just about human-sized. For millennia, the range of human experience was limited to this meso scale of phenomena that we humans could experience with our five senses. But beyond this understanding, there exist phenomena both sub- and super- in scale, not beyond human comprehension or reach, just beyond our everyday experience.
This is why quantum mechanics — the fundamental language of the universe on much smaller scales, dabbling in atoms and particles — is often the first topic students encounter that goes against the instincts they’ve built from living in the meso-world.
Grappling with this apparent magic begins to re-orient a physicist’s instincts, often for the first time. We start to think of waves as particles, particles as waves; we move from deterministic certainty to probabilistic predictions; we consider the effect of the observer in an experiment. Instead of being disappointed in the existence of the proverbial trap door under the hat, we know that there is also a state where the rabbit quantum-tunneled out of the cylinder.
By the end of my first semester of quantum physics, having encountered these seemingly magical phenomena and their scientific explanations, I was no less spellbound. The magic of the universe that conspired to create awe-inducing quantum phenomena is only enhanced by understanding the science behind it.
A similar scale shift happens when studying general relativity, Einstein’s reformulation of Newtonian gravity. Though both identically describe the experience of gravity on Earth, general relativity tells us how it behaves on much larger scales and at incredible speeds.
The poster child for general relativity is a black hole – a region of spacetime where gravity is so strong that it bends spacetime. Any object unlucky enough to fall into it will be stretched out in a process aptly known as “spaghettification.” If the magician’s hat were a black hole, no trap door would be necessary: the rabbit could never leave it, instead becoming noodle-thin while falling into the hat forever. It almost seems more magical than the magician’s rabbit trick, though with absolutely no deceit or sleight of hand. A black hole is genuinely ravenous, and the physics is sound; take as proof the recent spellbinding pictures of one gobbling up the innards of our own galaxy.
Like a conjurer’s trick, quantum mechanics and general relativity both defy our expectations; rather than fooling us, they challenge us to think beyond our meso-world models. Though they describe the sub- and super-world, they are neither sub- nor supernatural — or even weird. They are crucial to our understanding of the very foundations of nature.
Even while we know this to be true, we also know that these theories do not tell the complete picture. We still don’t understand how general relativity and quantum mechanics fit together to make up our universe and everything in it; how to at once describe atoms but also black holes. The quest to reconcile quantum mechanics and general relativity — the quest of quantum gravity — is one of the central motivations of theoretical physics today, and will likely be so for years to come.
In the meantime, physics continues to explore new and old ideas about the secrets our universe is hiding up its sleeve.
Every generation of scientists learns a few tricks from the previous generation, and advances in technology are accelerating the pace of this process. Whereas magicians guard their secrets to keep the audience guessing, scientists share their discoveries to keep the audience — and each other — learning.
We all see further, like Newton, by standing on the shoulders of giants. Science in general, and physics in particular, is a group endeavour only made possible by community. No black hole was imaged, or particles smashed, or gravitational waves measured without a team of many scientists working toward a common goal.
Magic tricks may inspire awe and wonder, but only the magic of science is enhanced, not diminished, each time we reveal its secrets. After all, Sir Terry Pratchett said it best: it’s still magic even if you know how it’s done.
Luna Zagorac is a particle cosmologist at Perimeter Institute. Check out her Q&A interview with FirstPrinciples.
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