Quantum biology: Do weird physics effects abound in nature?
Disappearing in one place and reappearing in another. Being in two places at once. Communicating information seemingly faster than the speed of light.
This kind of weird behaviour is commonplace in dark, still laboratories studying the branch of physics called quantum mechanics, but what might it have to do with fresh flowers, migrating birds, and the smell of rotten eggs?
Welcome to the frontier of what is called quantum biology.
It is still a tentative, even speculative discipline, but what scientists are learning from it might just spark revolutions in the development of new drugs, computers and perfumes - or even help in the fight against cancer.
Find out more
Until recently, the delicate states of matter predicted by quantum mechanics have only been accessed with the most careful experiments: isolated particles at blisteringly low temperatures or pressures approaching that of deep space.
The idea that biology - impossibly warm, wet and messy to your average physicist - should play host to these states was almost heretical.
But a few strands of evidence were bringing the idea into the mainstream, said Luca Turin of the Fleming Institute in Greece.
"There are definitely three areas that have turned out to be manifestly quantum," Dr Turin told the BBC. "These three things... have dispelled the idea that quantum mechanics had nothing to say about biology."
The most established of the three is photosynthesis - the staggeringly efficient process by which plants and some bacteria build the molecules they need, using energy from sunlight. It seems to use what is called "superposition" - being seemingly in more than one place at one time.
Watch the process closely enough and it appears there are little packets of energy simultaneously "trying" all of the possible paths to get where they need to go, and then settling on the most efficient.
"Biology seems to have been able to use these subtle effects in a warm, wet environment and still maintain the [superposition]. How it does that we don't understand," Richard Cogdell of the University of Glasgow told the BBC.
But the surprise may not stop at plants - there are good hints that the trickery is present in animals, too: the navigational feats of birds that cross countries, continents or even fly pole to pole present a compelling behavioural case.
Experiments show that European robins only oriented themselves for migration under certain colours of light, and that very weak radio waves could completely mix up their sense of direction. Neither should affect the standard compass that biologists once believed birds had within their cells.
What makes more sense is the quantum effect of entanglement. Under quantum rules, no matter how far apart an "entangled" pair of particles gets, each seems to "know" what the other is up to - they can even seem to pass information to one another faster than the speed of light.
The weird world of quantum mechanics
Quantum mechanics starts with the simple idea that energy does not come in just any amount; it comes in discrete chunks, called quanta. But deeper into the theory, some truly surprising - and useful - effects crop up
- Superposition: A particle exists in a number of possible states or locations simultaneously - strictly, an electron might be in the tip of your finger and in the furthest corner of the Universe at the same time. It is only when we observe the particle that it 'chooses' one particular state
- Entanglement: Two particles can become entangled so that their properties depend on each other - no matter how far apart they get. A measurement of one seems to affect the measurement of the other instantaneously - an idea even Einstein called "spooky"
- Tunnelling: A particle can break through an energy barrier, seeming to disappear on one side of it and reappear on the other. Lots of modern electronics and imaging depends on this effect
Experiments suggest this is going on within single molecules in birds' eyes, and John Morton of University College London explained that the way birds sense it could be stranger still.
"You could think about that as... a kind of 'heads-up display' like what pilots have: an image of the magnetic field... imprinted on top of the image that they see around them," he said.
The idea continues to be somewhat controversial - as is the one that your nose might be doing a bit of quantum biology.
Most smell researchers think the way that we smell has to do only with the shapes of odour molecules matching those of receptors in our noses.
But Dr Turin believes that the way smell molecules wiggle and vibrate is responsible - thanks to the quantum effect called tunnelling.
The idea holds that electrons in the receptors in our noses disappear on one side of a smell molecule and reappear on the other, leaving a little bit of energy behind in the process.
A paper published in Plos One this week shows that people can tell the difference between two molecules of identical shape but with different vibrations, suggesting that shape is not the only thing at work.
What intrigues all these researchers is how much more quantum trickery may be out there in nature.
"Are these three fields the tip of the iceberg, or is there actually no iceberg underneath?" asked Dr Turin. "We just don't know. And we won't know until we go and look."'Hugely important'
That question has ignited a global push. In 2012, the European Science Foundation launched its Farquest programme, aiming to map out a pan-European quantum research structure in which quantum biology plays a big role.
And the US defence research agency, Darpa, has been running a nationwide quantum biology network since 2010. Departments dedicated to the topic are springing up in countries ranging from Germany to India.
A better understanding of smell could make the hit-and-miss business of making new fragrances more directed, and learning from nature's tricks could help with developing next-generation quantum computers.
But what the next wave of quantum biologists finds could be truly profound.
Simon Gane, a researcher at the Royal National Throat, Nose and Ear Hospital and lead author of the Plos One paper, said that the tiny receptors in our noses are what are called G-protein coupled receptors.
"They're a sub-family of the receptors we have on all cells in our body - they're the targets of most drug development," he explained.
"What if - and this is a very big if - there's a major form of receptor-drug interaction that we're just not noticing because we're not looking for a quantum effect? That would have profound implications for drug development, design and discovery."
Jim Al-Khalili of the University of Surrey is investigating whether tunnelling occurs during mutations to our DNA - a question that may be relevant to the evolution of life itself, or cancer research.
He told the BBC: "If quantum tunnelling is an important mechanism in mutations, is quantum mechanics going to somehow answer some of the questions about how a cell becomes cancerous?
"And suddenly you think, 'Wow!' Quantum mechanics is not just a crazy side issue or a fringe field where some people are looking at some cranky ideas. If it really might help answer some of the very big questions in science, then it's hugely important."