Of all the theories scientists have thought up over the years, few have caused as many headaches as quantum mechanics. It’s the branch of physics that focuses on the small stuff – atoms, particles, electrons – but it manages to make some pretty big claims about the nature of reality. According to quantum mechanics, particles can move in many directions at once, atoms can spin clockwise and anti-clockwise at the same time, and cats in boxes can be both alive and dead.*

Quantum mechanics is so surreal that Albert Einstein, who more or less came up with the idea, ended up arguing that it was too illogical to be true. (When the most celebrated brain on the planet thinks an idea is too weird, you know you’re dealing with some complicated stuff.) But while humans struggle to understand its slippery logic, it turns out some far lesser brains are able to grasp quantum mechanics rather well. According to recent studies, birds – from the mightiest hawks down to the most pathetic pigeons – might be using quantum mechanics to help them navigate as they fly across the planet.

Literal birdbrains doing theoretical physics might sound farfetched, but the idea is gaining some serious traction in the (admittedly small) Venn diagram where physics and ornithology overlap.

Scott Weidensaul has followed these developments closely. A natural history writer from Pennsylvania, Weidensaul has spent the better part of his life studying, drawing, capturing and otherwise daydreaming about birds. He’s particularly interested in working out how they manage to fly around the world without consulting a map. “A ruby-throated hummingbird is about as big as your thumb,” he says down the line from his home office outside Philadelphia. “It weighs two-and-a-half grams and has a brain the size of a Tic Tac. And yet every year it makes this remarkable flight from Canada to Central America, returning each time to the same breeding ground, in the same backyard, in the same tree. Half the time, I can’t find my keys.”

This navigational ability has long filled Weidensaul with awe (as well as a profound sense of inadequacy). Growing up close to one of the world’s great bird migration centres, a place called Hawk Mountain Sanctuary, Weidensaul had a front row seat to an amazing spectacle. “Every fall I would sit up on the mountaintop watching this parade of tens of thousands of hawks and eagles and falcons heading south. And I realised I was watching birds that were born in the arctic tundra of Greenland or the boreal forests of Labrador as they headed all the way to Tierra del Fuego, the southern tip of South America. Twice a year the whole world was passing through my backyard. That was incredibly powerful.”

That realisation eventually led Weidensaul to study ornithology at university, where he attempted to unravel the mysteries of migration. “In the 1970s, I was taught that birds have a magnetic sense that they use to orient themselves. We were told there were little deposits of magnetic crystals in their brains or beaks that would act like compasses and essentially pull their noses north.”

On the surface, that theory isn’t so far-fetched. Plenty of organisms, from bacteria to whales, have been shown to have a magnetic sense (there’s some evidence humans may have it too). “But even in the ’70s,” Weidensaul says, “some scientists noted that things didn’t really add up with this neat little explanation – the biochemistry involving magnetic force is incredibly weak.” Too weak, he says, to facilitate a round-the-world trip with pinpoint accuracy. That is, unless the birds were somehow picking things up at the quantum level.

“In 1996, a mathematician at the University of Rochester stumbled across some startling evidence that honeybees might be able to see six-dimensional objects.”

To understand what might be going on in a bird’s brain, you first have to get your head around quantum entanglement. It’s what happens when two particles created at the same time become inextricably linked, even if they’re separated by great distances. Let’s say you have two electrons, and using some very precise magnets, you get one of them to start spinning clockwise. Because they are both ‘entangled’, the other electron will instantly spin in the opposite direction. This is true if your electrons are just a few nanometres away from one another, but it holds even if you’ve moved one of them all the way across the other side of the galaxy. Einstein dismissed the phenomenon “spooky” (it’s why he ultimately turned his back on quantum mechanics), but according to more recent studies, it actually checks out.

What’s this got to do with birds? Well, scientists now think the tiny animals might be using quantum entanglement to see the earth’s magnetic field. It’s a theory that’s been doing the rounds since the 1970s, but it’s taken decades for physicists to begin to unravel how they might do this. Many, including Weidensaul, now believe that when blue light enters a bird’s eye, an entangled electron in its retina gets dislodged, and moves a few nanometres away from its partner. These ever-so-slightly separated electrons then hit the magnetic field from ever-so-slightly different angles, resulting in different concentrations of chemicals forming in the eye. Physicists believe these chemicals create a map-like image of the magnetic field in the bird’s eye, which it uses to orient itself.

The idea that birds can detect something as small as a single electron might seem hard to believe, but Weidensaul isn’t fazed. “To be honest, I am prepared to believe damn near anything about migratory birds at this point. They’re using quantum entanglement? Okay, sure. To me, that’s not necessarily any more staggering than the notion that a bird flying down the centre of North America can hear the waves of the Atlantic Ocean in one ear [which they can], and wind blowing through the high passes of the Rocky Mountains in the other [ditto], and the rumble of volcanoes and earthquakes in the volcanic mountains in Mexico [also true]. It’s all equally incomprehensible.”

It’s these kinds of extra-sensory abilities that most excite Weidensaul. “They’re a reminder that the world is bigger than we know. And bigger than we can know. Birds can tap into physical spheres that humans are largely blind and deaf to,” he says. And not just birds. “These abilities may be more widespread in the animal kingdom than we realise.”

Above: manifolds of different dimensions, care of Wikipedia

The notion that the animals might know something we don’t is pervasive. Stories abound of elephants fleeing seemingly calm Southeast Asian beaches moments before the 2004 tsunami hit, as do more spurious anecdotes about barking dogs being good judges of character. But the most interesting theory about animal extrasensory ability concerns creatures altogether smaller and more complex. In 1996, Barbara Shipman, then a mathematician at the University of Rochester in New York, stumbled across some startling evidence that honeybees might be able to see six-dimensional objects.

She arrived at this theory, in part, by trying to solve a question that had been bugging entomologists for decades: how do bees, whose brains only contain a measly few million neurons, manage to perform the intricate dances they use to communicate the precise location of newly discovered food? How can their tiny heads encode so much information?

The question had been on Shipman’s mind since she was a child. Her father was a government bee researcher, and often showed his children the waggle dance that his bees performed to communicate with each other. If you traced the outline of this dance on a piece of honeycomb, it looked a bit like a coffee bean. Apiarists had known since the ’60s that certain steps in the coffee bean dance represented how far away a food source was, while other parts indicated the direction. Still, no one could work out how the bees could possibly be performing all this geometry in their heads.

Years later, now a mathematician studying extra-dimensional spaces called manifolds, Shipman noticed something that reminded her of her father’s bees. Manifolds are mathematical objects that allow scientists to imagine what the universe might look like if it had, say, five dimensions instead of three. One day, Shipman decided to draw a two-dimensional outline of something called a flag manifold, which has six dimensions (and apparently looks a bit like a flag hanging from a pole). Obviously you can’t accurately draw six-dimensional space on a piece of paper, but you can project a two-dimensional outline of it, in the same way a three-dimensional ball can cast a circular shadow onto a flat wall.

Curiously, when Shipman projected the flag  manifold onto her piece of paper, it formed a hexagon – the same shape as a piece of honeycomb. Even more interesting, though, is what happened when she started to draw the kinds of objects that might exist in six-dimensional space on the same piece of paper: they formed coffee bean-shaped outlines over the honeycomb: the exact same patterns that the bees dance in their hives.

So, could bees somehow be dancing in six-dimensional space in the same way birds are able to “see” the magnetic field? It’s an enticing idea, though perhaps too enticing to be real. In the 20 years since she first published her hypothesis, Shipman, who now teaches at the University of Texas, has been quiet on the bee front. She has published no further papers on the theory, and did not respond when asked for comment. No other academics appear to have continued her research. (One entomologist recently derided her ideas as “ridiculous”.)

Still, given what we now know about birds and quantum entanglement, Shipman’s theory about six-dimensional bees doesn’t seem altogether that much more ridiculous. Weidensaul wasn’t familiar with Shipman’s work (he’s very much a bird guy). But after hearing about it and the theory she arrived at some 20 years ago, he offered this thought. “The smallest sparrow picking up crumbs by an outdoor cafe can see the world in ways that would leave us absolutely dumbstruck. Travelling through the earth’s magnetic field and seeing it change, it must be amazing – like the Aurora Borealis, though more beautiful.

 “The most common bird on the street can see that, and I can’t. I wish to god I could.”

* A quick note: we’re simplifying things a tad here. Atoms don’t actually spin, strictly speaking, though scientists seem to agree that spinning is a useful metaphor to use when explaining “atomic superstates”. For more accurate information, please consult a physicist.

Originally published in Smith Journal vol. 19