In this Friday Evening Discourse at the Royal Institution, Professor Jim Al-Khalili explores how the mysteries of quantum theory might be observable at the biological level.
Jim’s book “Life on the Edge: The Coming of Age of Quantum Biology” is available to buy now –
Although many examples can be found in the scientific literature dating back half a century, there is still no widespread acceptance that quantum mechanics — that baffling yet powerful theory of the subatomic world — might play an important role in biological processes. Biology is, at its most basic, chemistry, and chemistry is built on the rules of quantum mechanics in the way atoms and molecules behave and fit together.
As Jim explains, biologists have until recently been dismissive of counter-intuitive aspects of the theory and feel it to be unnecessary, preferring their traditional ball-and-stick models of the molecular structures of life. Likewise, physicists have been reluctant to venture into the messy and complex world of the living cell – why should they when they can test their theories far more cleanly in the controlled environment of the physics lab?
But now, experimental techniques in biology have become so sophisticated that the time is ripe for testing ideas familiar to quantum physicists. Can quantum phenomena in the subatomic world impact the biological level and be present in living cells or processes – from the way proteins fold or genes mutate and the way plants harness light in photosynthesis to the way some birds navigate using the Earth’s magnetic field? All appear to utilise what Jim terms “the weirdness of the quantum world”.
The discourse explores multiple theories of quantum mechanics, from superposition to quantum tunnelling, and reveals why “the most powerful theory in the whole of science” remains incredibly mysterious. Plus, watch out for a fantastic explanation of the famous double slit experiment.
Watch this video on the Ri Channel with additional learning materials:
Friday Evening Discourses
The tradition of Friday evening discourses at the Royal Institution was started by Michael Faraday in 1825. Since that time most major scientific figures have spoken in the famous Lecture Theatre at the heart of the Ri building at 21 Albemarle Street. Notable talks include Faraday announcing the existence of the technology of photography in 1839 and J.J. Thomson announcing the existence of the fundamental particle later called the electron in 1897.
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thank you what I'm about to tell you this evening is introduced a new essentially a new area of science now I think many of you the scientists among you in the audience will be rather skeptical biologists don't like quantum mechanics maybe they don't believe quantum mechanics quantum physicists certainly don't want to get their hands dirty in the messy world of biology and so an area that brings the two together is is somewhat controversial and it is still a very speculative area of research the point is it's so exciting that I think if it's at all true that nature utilizes the strange rules of quantum mechanics then it's a worthwhile endeavor to investigate I was last here giving a Friday evening discourse nine years ago so I'm not publicizing my book this is a book that came out nine years ago and I was talking I talk generally about some of the strange aspects and features of the the subatomic world that subject to the rules of quantum mechanics what I like also is that on the back of the book is my favorite quote of all time by the Danish physicist Niels Bohr if you're not astonished by quantum mechanics then you haven't understood it you're meant to be astonished by it and even quantum physicists who spent their lives thinking about quantum phenomena should be astonished in fact if they're if they get very blase about it they should take a step back and think about exactly what it means now quantum biology is well this this image is a picture that appeared in nature an article written by the science writer Philip ball and it introduces some of the speculative ideas where quantum mechanics seems to be playing a role in biology and to introduce the subject I could have started from various different points but I think I will start by saying something of explaining why there's an image of a bird in this picture this is the European Robin it looks for those switches in the audience it looks slightly different and I'm not so I saw you know I had to look carefully to see the difference it looks rather different to our own British Robin the British Robin has a a deeper red breast than the rather fainter European cousin the other difference is that the British Robin remains here on these shores all year round because we have a reasonably temperate climate the European Robin that lives up in Scandinavia and Russia northern Europe obviously would like to find a warmer climate during the winter and migrates down to the Mediterranean were referred out of Spain and even down to the north coast of Africa and so it follows this path directly from central Sweden let's say as an example down to – to Spain and it knows how to navigate now this is not new we've known for a long time that many animals birds and marine creatures can find their way across many very often thousands of miles even if they've never done that journey before they use all sorts of tricks they use the position of the Sun sometimes they have a celestial map they know the positions of the stars if they migrate at night they will recognize local landmarks very often they sense the Earth's magnetic field they have an inbuilt compass now the first person to realize this so let me say something about the Earth's magnetic field what was actually quite surprising is that even to this day scientists don't really understand very well the origins of the Earth's magnetic field but roughly is to do with circular currents in the molten core of our planet that the induced magnetic fields due to the rotation of the earth so you can think of this giant bar magnet sitting at the very core of our planet and field lines circulating out of the earth and around our magnetic field is very important we think it's it formed between three and four billion years ago when the earth is very young it's certainly yet without the magnetic field we wouldn't be alive today because not only does it shield us from the from cosmic rays from outer space it stops those cosmic rays from knocking and blowing away our atmosphere and therefore water evaporating as we believe happened on Mars the first scientists to investigate the influence of the Earth's magnetic field on migrating birds was a Russian zoologist and Explorer Alexander von midden Hoff and he carried out experiments to find out how these birds migrated and what directions they took there were rather crude experiments but he postulated that they could sense somehow the presence of the earth weak magnetic field with some internal magnet's magnetic material that would act as a compass we know today that many creatures can sense the Earth's magnetic field from sea turtles to whales and dolphins to obviously many migrating birds to even to the trout and an even research suggests that ants have a bility to sense tiny changes magnetic field due to nano crystals of iron oxide in their antennae and that's that's basically the general idea that you have this these crystals of usually magnetite which are sensitive to the direction of the field and they can can affect electric pulses signals current sent by the neurons to to to the brain the the homing pigeon very often uses a whole range of different methods to find its way from remembering landmarks to following direction of the Sun but also many birds are found to have these tiny magnetite crystals in there at the ends of their beaks and what happens is if when when the birds is aligned in a particular direction relative to the Earth's magnetic field then that will cause these magnetic crystals to adjust and move and as they do they will create tiny currents and pulses that can be magnified and send signals via the neurons to the brain signaling to the bird to move in a particular direction this was discovered well the the notion that animals birds could actually detect the Earth's magnetic field goes back to the mid 19th century more recently work carried out in this late 60s and early 70s suggested that there was another way that certain animals certain birds could detect the presence of the field so this is a husband-and-wife team the Germans the real chicos who published controversial work in science in the early 70s they carried out an experiment on european robins and realized that the the robins certainly could sense the direction of the Earth's magnetic field but it wasn't doing it in the traditional way that we would use a compass so these birds weren't sensing which direction was north and which direction was south whatever compass they were using didn't depend on the polarity of the field and they carried out increasingly sophisticated experiments where they would capture these birds in and and and then put sort of artificial magnets outside these chambers where the birds were caught and reversed north and south of the magnets and see what happens and the birds didn't seem to be affected by which direction was north which direction was south they deduced that the birds weren't following a north-south direction within the field but rather pole to equator equator to pole and they realized that it wasn't the direction of the Earth's magnetic field but the angle of inclination of the field let me explain what I mean if you think about so this is the field lines these are these ants you know physical lines you remember the exactly experiments at school with iron filings iron filings will create the landscape of the magnetic field showing the direction of the field lines for the earth of course the field lines come out of the South Pole or equivalent to our geographic South Pole out and around and go in to the North Pole and so close to the poles the magnetic field lines are vertical or almost vertical but past the equator they are parallel to the ground and so depending on how far north or south you are the angle of inclination of the field changes and research suggested that the European Robin was somehow able to figure out a direction to travel based on the angle of inclination but it wasn't clear what that mechanism was so here's a contour map of lines of equal inclination angle and you can see that for instance if I put in the the path taken by the European Robin's they're moving roughly from a central Scandinavia with a inclination angle of about 76 degrees and and and there's a there's a change reduction angle of about 20 degrees down to the Mediterranean the strength of the magnetic field also changes the intensity it'll drop from something like just over half a Gauss to just under half a Gauss but it's there's no evidence yet that the birds are able to somehow calculate you know this is where I am because this the intensity of the the field is this and the angle of the inclination is this but somehow they utilize this information to tell them which direction to go so far so good this is not no longer really controversial many more sophisticated experiments have been carried out since the early 70s to convince scientists that the birds are able to do this what was puzzling of course was the mechanism it was still thought that it had maybe had something to do with these metal magnetic crystals in for instance in the bird speaks because the birds even the European Robin would utilize various different techniques even if it followed this rather strange mysterious method of knowing the angle of inclination or the magnetic field to find its way it certainly used other more traditional ways to find its way back for instance possibly using these magnetic crystals but how does it find its direction in the first place the mechanism that was proposed was made by a group at University of California Irvine about a decade ago and it's based on a process that takes place down at the molecular level something called radical pair mechanism so what I'm going I'm going to dive in here into some quantum mechanics that is rather complicated I'll zoom back out again and tell you a bit more about the weirdness of quantum mechanics in a few minutes so here's the title of their paper a model for photoreceptor based magnetoreception in birds the idea was that whatever the mechanism was going on it seems that the birds were able to somehow see sense through their eyes the direction they should travel through the Earth's magnetic field and the clue was a particular protein in the photoreceptor cells at the back on the back wall of the bird's retina protein called cryptochrome cryptochrome is known to be it it's stimulated by light particular wavelength of light typically blue light that can excite atoms within the protein and so which is why hats cryptochrome had to be in the birds I fought for it to work because it had to actually have light coming into the eye to get this mechanism working it's still controversial whether the process takes place in just the birds right eye or both eyes it would seem strange that it's only well you'd think evolution would would be a bit more you know sort of free and easy about which particular I would be used which surely birds that could utilize mechanism both eyes would would have some evolutionary advantage nevertheless here's the here's the quantum mechanics that takes place two electrons in an atom can exist in what's called a quantum state so they have the same energy but they have to spin in opposite directions so in a very broad rather non accurate quantum mechanical way we can say one spins clockwise and one spins anti-clockwise and they form a pair and if one is spinning clockwise the other one has to spin anti-clockwise otherwise it has to go and live somewhere else this is something called the power Li exclusion principle which says that there are rules about how many electrons can be close together in the same state and and what direction they spin in in cryptochrome is thought that light photons particles of light will come in and hit and knock one of those electrons in the pair and that electron will be knocked off into an adjacent molecule forming what's called a radical pair molecules that molecules that are both electrically charged one is now positively charged because it's lost an electron one is negatively charged because it's gained an electron that's fine what's magical quantum mechanically is that although these electrons are far apart sitting on living on different molecules they still still know about each other's existence if one is spinning one way the other one doesn't have a choice they can exist in particular quantum states the technical jargon is they can exist in what's called a singlet state or a triplet state depending on whether their spins are aligned both clockwise or anti-clockwise or opposite now quantum entanglement is the idea that particles however far apart they are still somehow their fates remain intertwined they they are still aware of each other's existence last year's Nobel Prize for Physics was awarded to the two leaders of two research labs one in France one in America where they've pioneered research within physics nothing to do with biology but within the very sort of clean simple environment of a physics lab where you think you can get hold of and understand these quantum mechanisms and so quantum entanglement even for physicists is a rather novel thing for it to take place inside these molecules of the the cryptochrome protein inside a cell at the at the back of a retina of a bird and somehow play a role in helping the bird navigate would seem very very strange indeed but these two electrons that are far apart that are entangled how they behave and the way they spin affects what chemical reactions those molecules can induce within the cell different chemical reactions would send different signals to the bird's brain the magnetic field outside that the bird is flying through effects these two electrons these entangled electrons and so the direction the bird is moving affects the chemical reactions that this radical pair of molecules can cause to take place within the retina two things to say about this first of all that it is it's not confirmed that this is the mechanism that takes place it's the the the leading candidate to explain how the the bird does what it does it's known that it sees the magnetic field somehow it's known that it does it somehow through its eyes it's known that they kick it within the eyes this protein called cryptochrome that is photosensitive but it's not we're not sure that this is what takes place the the sketches ISM arises because quantum entanglement is a very weird and delicate quantum process the the mechanisms that take place in the quantum world disappear very quickly once you you make your system complicated once you rather have just a single atom you can imagine a single atom we do experiments like this where you send an atom it can go in two directions at once and I'll say something about that in a moment but the notion that that atom can do this strange quantum behavior of doing two things at once or electrons doing two things at once or electrons being somehow connected at a distance what Albert Einstein said spooky action at a distance which is why I signed didn't like some of the features of quantum mechanics for that to take place within the warm complex messy environment of a living cell was something that most scientists had discounted until recently because it was deemed to be a process that would just disappear evaporate what we call decohere very very quickly far quicker than the biological timescale needed for you know there's no point these radical these electrons they entangled for tiny you know billions trillions of second and then somehow that's it the quantum effect has gone that's no use to the birds somehow it's maintaining this quantum behavior for longer if this is true if quantum entanglement really does play a role well there are other quantum phenomena that go on in the world in the subatomic world how many of them play a role in in living cells we know that all essentially let's imagine you know the living cell the human brain or any any organism is made up of cells and those cells are very complicated complex cities involving processes voting proteins and enzymes and there's so much going on zoom in and you can imagine it's sort of a mechanistic which is why biologists to this day still feel more comfortable with their balls and sticks models of molecular structure and it's acknowledged that if you look down deep enough into molecular biology at its heart it's essentially organic chemistry an organic chemistry is of course subject to the rules of quantum mechanics because quantum mechanics tells the atoms the electrons how to arrange themselves within atoms how the atoms fit together to the molecules and so on as you zoom out but can those quantum effects somehow leave an imprint on the macroscopic world while it's useful to remind you that living organisms really are the only macroscopic objects whose dynamics are controlled by a single molecule very often a single molecule can affect the whole organism you can think of this in terms of a mutation in DNA for instance a single mutation a change down at the molecular level can propagate and have a magnified effect on the whole organism until recently this was deemed to be rather cranky to be honest ten years ago I don't think I'd even be brave enough to give this talk because I'd be seen as one of the the crackpots and aligned with the many sweet souls who write to me and email me on a regular basis with their new theories of the universe which I collect by the way in a box older because they're very sweet but one such cranky idea was around I guess 2025 years ago and it was the idea of human consciousness be having a quantum origin the reason it gained any traction at all was because one of the two people involved in proposing this idea was Roger Penrose one of the greatest mathematical physicists alive in the world today and Roger Penrose who if you don't know him he's a cosmologists and he did a lot of early work in the seventy with Stephen Hawking in developing the mathematics of the Big Bang and and the properties of black holes he teamed up with this other guy Hameroff published their ideas about whether we could understand the nature of consciousness through quantum mechanics the notion that within the neurons in the brain are proteins microtubules which can have four to different shapes at the same time you know in Compton the quantum world things can do two things at once so these molecules could be in two different shapes at the same time and that was fine that quantum behavior could sort of propagate if enough of these these molecules would do were playing the quantum game then it would reach some sort of threshold and that threshold would collapse the quantum state and that's was was deemed to be the switching on of consciousness and it was very very fluffy and very hand wavy and very dodgy the idea was that quantum mechanics is very very weird and we don't really understand it consciousness is really weird we don't understand it the two must be connected and for a while there were in the late 80s and early 90s there were lots of interdisciplinary workshops and conferences that brought together philosophers and biologists and quantum physicists and computer scientists and so on because it was this what seem to be that you know the new big thing and it sort of died down so if we are going to see quantum effects in biology I think we have to step back and try not to be so ambitious and and and look a bit more carefully but I want to remind you of just how weird the quantum world is I'm going to explain to you what's known as the central mystery of quantum it was a Richard Fineman the American physicist said this is the central mystery of quantum mechanics there's lots of weird stuff that goes on in the quantum world hit you with this and it basically tells you what it's all about it's called the two-slit experiment I'll start with this imagine you have a source of light shining against the screen with two slits now for the pendants in the audience this source of light has to be monochromatic light light of a particular wavelength well where's of course a light bulb is white light and that's made up of all the colors and spectrum lots of different wavelengths but I imagine this is just a single wavelength of light and you can see the light is coming out in in waves like like ripples in a pond that's the nature of wave-like behavior as the light hits the screen it squeezes through the two slits and each slit in turn on the other side becomes almost like a new source of light and the light spreads out it diffracts and as the waves of light overlap they will interfere with each other so where a crest hits a trough they will cancel where crest hits a crest they will amplify and so on and so on the back screen you end up with what's called an interference pattern a series of light and dark fringes where the waves have either cancelled out or worked together in phase that's fine that's not quantum mechanics that's a property of light that goes back over 200 years that we've known about since the early 19th century imagine doing the same experiment again but doing it not with waves but with particles do it with grains of sand so this is the same experiment but I've tipped it 90 degrees rather than waves that are spread out that wash up against the two slits and squeeze through here you've got individual particles of sand and each particle would either go through one slit or the other and so you see there will sort of drain through and you get two bumps underneath each of the slits so the two peaks is reminiscent of particle-like behavior whereas the the multiple pattern of interference is wave-like behavior what if we do the same experiment with atoms well so imagine we have an atom gun something can fire atoms as a stream of atoms you can't see them because they're very small let's block off one of the two slits so these two slits are you know the the dimensions and separation of the slits is chosen appropriately to show us how atoms do things and so far so good nothing strange here you'll see a lot of atoms hitting the back screw so this will now have to be some sort of photosensitive screen where whereby when an atom hits it they'll it'll give off a little flash of light to say the atom has arrived here so the atoms are arriving is this little pinpricks of light that we see of course a lot of the atoms will be blocked by the first screen they won't go through that slit but those that do get through to the other side you can see there's a bit of spreading of the atoms but if we didn't know anything about atoms you say well that's fine we can understand that some a lot of the atoms are going clean through the slits some are sort of maybe bouncing off the edge of the slit and so they're sort of being deflected a bit which is why you get a bit a bit of a spread the first mystery of quantum mechanics comes when we open the second slit because now we see something that's very much like the interference pattern we got with light rather than having two bands of spots where the atoms have gone through the two slits it's as though the atoms have gone through the slits behaving like waves and and into and and you get interference of the waves and you get these bands if we know nothing about atoms or quantum mechanics you could try and rationalize and say well you know maybe atoms behave in a very strange way and only a certain number of them are allowed to all sit together and so you know me and my gang we're all going to go on this slit no sorry no room for you you go the next bit above and by the way there's this rule that no one can go in between the two met bands but a few naughty atoms do so there's a bit of a scatter you know we don't there could be some forces between atoms that make them coordinate their actions in a way to give this pattern that's not mysterious that's just we just don't know how atoms do things but we can be clever and we can force the issue what if we were to not send the atoms all through at once but send them through one at a time leave enough of a gap for the atoms to get through to hit the screen of course as I say some atoms will hit the hit the first screen and not get through but those that get through will hit the back screen so let's run the experiment again slowly and gradually you'll see as the atoms go through they'll be look like they're just randomly arriving on the other side you keep sending atoms through one at a time and gradually that same packing appears so each atom by itself is somehow contributing its small part to the overall wave-like behavior that we see in the interference pattern how does it do it how does we know the atoms are tiny localized particle we can't say it's too small to even see under a microscope with firing it at the screen with the two slits some moment later you see a flash of light on the back screen it's arrived in a localized point it's not spread itself out you don't get so like a wash of a sort of a faint light across the whole screen so a little point the Atem is localized arriving in a certain location and yet it somehow seems to have been aware of there being two slits not one because it's given rise to this interference pattern how does one Adam do that does it split in half does it become like a cloud that goes through both well we can try and be even cleverer what if we were to spy on the atom and see where it goes we're going to gently just observe which slit it goes through so you put a detector just above the upper slit that will flash or beep whenever it sees an atom go through that top slit sure enough you fire the atoms through one at a time 50% of the time the detector will beep the other 50% of time it doesn't the assumption being that the atoms has gone through the lower slit but of course I've been cheeky here I haven't shown you the results of the experiment that's where you get 50% of the time it beeps and you see a spot arrive adjacent to the upper slit the other half of the time it doesn't beep but you see a spot arrive at the lowest it so yeah it's picked out the atoms that have gone through the upper slit and not the ones that go until each atom does go through one slit or the other but that's a different result to what we had earlier so here's the last bit of sneakiness that we can play with atoms surely now you know we're going to get to grips with it leave the detector there but just very quietly go and unplug it don't let the atoms know that you're not spying on them make them think that you're still detecting them so yeah okay we're gonna run the experiment a soms okay get ready one at a time we're going to be checking on you all right so run the experiment again now if you can explain this using common sense and logic do let me know because there's a nobel prize for you quantum mechanics is the most powerful theory in the whole of science and as a physicist yeah I mean okay the biologists may disagree but it Biggs Darwin's theory of natural selection with one hand behind its back because quantum mechanics underpins so much of physics pretty much all of modern chemistry and therefore potentially biology without quantum mechanics we wouldn't have electronics wouldn't understand what a semiconductor is we wouldn't have lasers we wouldn't have most of modern technology that we use today if quantum mechanics wasn't right in explaining the rules of how the microscopic world behaves and how atoms fit together and yet at its heart it is incredibly mysterious now quantum physicists have had almost a century to get their heads around this and in a way they have because that the mathematics of quantum mechanics is perfectly well developed and it's very powerful and predictive and it helps us explain the subatomic world but we've got a plug like half a dozen different ways of explaining how those atoms get through the slits none of them are very satisfactory the standard one believe it or not the standard way of explaining it is to say don't worry your pretty little heads about how the atom does it you can never know all quantum mechanics ever tells you is it makes predictions about the results of experiments when you went when you go and observe something so quantum mechanics will indeed the mathematics will tell you if you're not looking you'll get the interference pattern if you're looking it'll disappear and hence uuuuu here if you figure in the popular science talking about the role of the observer is central and it leads to all sorts of wacky ideas like you know in the nature of consciousness and so on in quantum mechanics so quantum mechanics is weird there's no getting around it it's not that it's just weird in biology it's weird for physicists and it's sort of time that physicists let the biologists know that you know we've had all these years of sleepless nights and worrying how atoms do these things it's about time you you know got very very concerned about the subatomic world my research expertise is in nuclear physics and so I can give you an example a real-world example of something similar to this atom somehow going in two directions at once it's called superposition the idea that the atom can follow more than one path or can exist in more than one state a famous example in nuclear physics is that of a particular nucleus of a particular isotope of lead lead 186 now what we do in nuclear physics is try and understand how the protons are Neutron the particles that make up the nucleus of the atom this is not I'm talking nucleus of atoms not nucleus of cells here so I'm doing the physics physicist definition the nucleus of the axon is made up of protons and neutrons and understanding how the protons and neutrons arrange themselves according to the rules of quantum mechanics well this particular nucleus because nuclei come in different shapes some of them vibrate some of them are stretched some of them are squeezed some of them have protons and neutrons sort of floating around in different arrangements they some of them have clusters of protons and neutrons let the nucleus of lead 186 seemed to be able to exist in three different shapes at once it's not that it's so the three shapes there's a sphere then you hear its prolate which is rugby ball shape and oblate you know get up get a ball and squash it so flap like a flying saucer it's not that this nucleus is sort of moving around in time and changing its shape when you're not looking at it which is always the weird thing in quantum mechanics it behaves as though it coexists in a sooner superposition superimposed three shapes at the same time when you look it stops it does 1 1 1 or other of these things so how do you know while there are lots of experiments we can do that would come out different if the quantum world wasn't behaving in this way we know that when we're not looking it does weird things like the atom going through the two slits the over the last few years it's been a lot of research has gone into this idea of superposition manifesting itself in biology and that is in understanding the process of photosynthesis it's a particular large complicated molecule called the FMO complex which delivers the energy from the light the this falls on the leaf down to the reaction center in the middle of the cell and all the indications are that this energy is delivered by something called an exciton which is essentially an electron removed from an atom and then jumping down along with the empty hole it's left behind it's so it's a very sort of abstract notion but essentially down at the atomic scale this energy is being carried by particles down and what seems to happen is it doesn't just follow one route through this molecule but it follows all possible paths and then somehow Katri calculates which one of them was the most efficient one and says that's the route I have taken almost as though it's worked backwards in time that's the nature of quantum superposition and quantum physicists have had many years scratching their heads thinking hang on that just doesn't make sense but that seems to be what nature does at the subatomic scale now molecular biologists are realizing that this quantum superposition looks like it takes place within in the process of photosynthesis well there are so I've mentioned superposition I've mentioned briefly quantum entanglement while I've mentioned quantum entanglement is this instantaneous somehow connection between two or more quantum particles that can be very far apart what does that mean that you know that how in a very far apart and yet somehow they're communicating with each other instantaneously so here's a quick example imagine you take two dice so I've got one and some one at the back of the lecture that has another and we throw them together it'd be very strange if they've kept landing on the same number somehow that there there were their actions were coordinated and correlated we say somehow they were entangled well we can check maybe they are they've gotten to presumably if we know this if there's no such thing as magic they have some in a mechanism machinery that makes them land on particular numbers sort of a sequence of numbers that's pre-programmed into each of the two dice but you could check that by throwing one of them and just breaking the sequence and if they carried on doing that then presumably they're signalling to each other so one of them must land a fraction of a second before the other and say I'm on a 5 and the gears were inside the the other one it and it flips onto a 5 and so it and maybe does it very quickly well how quickly the fastest we can signal anything can signal from A to B is at the speed of light nothing goes faster than the speed of light what if we were then to repeat this experiment with the dice very far apart imagine scientists on earth and scientists on Pluto it's not a planet but at least let's let's let's assume it has scientists working there there which is that's what they look like and I've chosen Pluto because it takes light several hours to get between Earth and Pluto so if the earth and Pluto scientists run conduct this experiment each throwing their die and they land on the same number every time and they come back afterwards and compare notes and if they throw them at a regularity that it's you know much shorter intervals that a time it takes even for light to be signaled between earth and Pluto then there must be somehow some instantaneous action that's going faster than like and Einstein's theory of relativity says that's not possible remember the the ball that the big news about these particles neutrinos that was supposed to be able to travel faster than light someone promised to eat their boxer shorts on TV if it was proven to be correct and luckily it was a mistake someone hadn't plugged in a cable properly nothing goes faster than light and yet at noon quantum world it does seem as though quantum entanglement requires instantaneous connections between particles however far apart they are and the truth is we don't know how to explain this without you know counterintuitive words or without abstract mathematics there isn't a logical way of explaining how quantum entanglement works well one very famous physicist was was very upset by the idea of entanglement in superposition so what happens if you have superposition one particle being able to do two things at once and entanglement that particle somehow infecting another particle very far apart while you get Schrodinger's cat Erwin Schrodinger in the 1930s came up with this thought experiment where he famously said he didn't really do the experiment he said if you were to put a cat in a box with a vial of poison that's connected to a mechanism that would release the poison if some radioactive material emitted a particle an alpha particle say the alpha particle which flies out of an atomic nucleus is subject to the rules of quantum mechanics and so quantum mechanics says if you close the box and you're not looking you can't say after any given time whether that Adam has spat out the alpha particle or not and it's not just your ignorance because you don't know because you haven't looked but quite literally the alpha-particle has both been emitted and not emitted at the same time that's what superposition says in the quantum world things do two things at once and that's what quantum mechanic would say about that radioactive atom but if the the the fate of the atom is entangled with the fate of the atoms in the cat and Schrodinger said after all you know cats are just made up of atoms so surely they should ultimately obey the rules of quantum mechanics then before you open the box the cat is also both dead because the poison has been emitted and alive because it hasn't and only when you open the box do you force the fate of the cat to be determined so it's not that the cat is either dead or alive when you just don't know yet it really is both it's dead alive at the same time until you open the box and this got quantum physicists or very uptight and this at all Schrodinger you don't understand quantum mechanics but actually looking back at it now we sort of understand that in complicated systems like a cat made up of trillions of atoms it's very hard to maintain the quantum behavior that the quantum behavior the entanglement the superposition is fine it works down at level of a single individual atoms but once that atom is is surrounded by trillions of other atoms in a complicated system then the quantum weirdness very quickly dissipates and leaks away far too quickly for a cat to ever be dead and live at the same time so in the 1930s after the experiment physicists started thinking about how there must be a barrier boundary between what goes on weirdly at the subatomic scale once you have isolated atoms and molecules but that somehow disappears once you have a complex system and therefore surely inside a living cell quantum weirdness must disappear dissipate what we call decohere very very quickly well a few years later Schrodinger wrote a famous book called what is life and I just read you a quick extract the living organism seems to be a macroscopic system which in part of its behavior approaches purely mechanical as contrasted to thermo dynamical behavior to which all systems tend as the temperature approaches the absolute zero and the molecular disorder is removed basically what he was saying was we know that if you get something if you cool something down too close to absolute zero you stop all the vibrations and and energy being exchanged you start to see quantum behavior emerging but once it gets very warm and complex that quantum behavior disappears Schrodinger was try it was suggesting that maybe inside a living cell it's structured and behaves as though it were inanimate matter at close to absolute zero that it has an ordered structure that allowed for quantum mechanics to play around and really you know that question and it's probably fair to say that question hasn't yet been answered most physicists would be very skeptical about the possibility of quantum behavior appearing in so biological systems until recently and some of these phenomena in quantum biology so the question was from the 1940s is live quantum mechanical certainly ensuring his book what his life was hugely influential for many people including Crick and Watson who went on a few years later to discover the structure of DNA but it doesn't it's controversial it's speculative but it does lead to also eat much bigger questions after all probably the biggest question in the whole of science is how did life form in the first place what was that magical step between inanimate matter and something that can replicate itself we don't know yet I said well another way of saying is how did chemistry become biology and can quantum mechanics lend a helping hand well it starts to smack like it's a smack of that idea of quantum mechanics and comes business just because there's a question we don't understand strange and quantum mechanics are strange doesn't mean the two are connected how then can we investigate quantum behavior in biological systems a bit more carefully and and step by step right without sort of jumping too far ahead of the gum one process that I have been interested in recently is it's called quantum tunneling and I would say it's sort of halfway between mundane quantum mechanics which is the rules of quantum mechanics that you have to apply in organic chemistry to describe how molecules fit together including those molecules in living cells and the more outlandish quantum behavior superpositions and entanglement and so on quantum tunneling is the process whereby a quantum entity a quantum particle can somehow punch its way through a barrier a force field and energy field that it has no right to be able to get through in in the everyday world it's the equivalent of me running straight through that wall disappearing and appearing on the other side it doesn't happen in the quantum world it seems that it does happen and in fact the picture I've got here is of the Sun the reason the Sun shines therefore the reason we are here is thanks to quantum tunneling because hydrogen nuclei protons should never be able to fuse together to make helium through the process of thermonuclear fusion which is what heaps and lights our Sun because two protons are both positively charged and they should repel each other but every now and again they get close enough together rather than repel each other they're not really attracted to each other unless they get very close because then the strong nuclear force that binds atomic nuclei together can get a hole get a grip but it's a very short range force and and the electrical repulsion doesn't allow the process to get close enough together but thanks to quantum tunneling every now and again a proton can come up to another one and somehow seep through the barrier quantum tunnel through the other side find itself close enough to the other proton that they can stick together quantum tunneling takes place all the time well we're looking into the possibility that quantum tunneling is an important process in biology as well chemists have known that quantum tunneling is important in organic chemistry for a long time and one of the wonderful things about this new field of quantum biology is that the physicists armed with their wonderful ideas about quantum mechanics and the biologists were understanding the complexity inside the cells are starting to you know let's let's figure this all out and the chemists bless them have been sitting a little saying baby boy we know all this we do come and have a look at how complicated the calculations we do quantum mechanically and sure enough a lot of chemists have been looking at quantum effects in inorganic chemistry in particular the nature of the hydrogen bond the hydrogen bond is essentially a hydrogen atom that holds some molecules together it's not a very powerful bond is strong enough for four structures molecules to fit together to make very complicated structures like proteins and enzymes but it's not too strong a bond that it can't be broken easily enough so that these molecules can rearrange themselves very often the hardening atom can jump from one place to another within a molecule also what you find is molecules stuck together with the glue that is a hydrogen bond and what we find is that the hydrogen atom well I'm going not going to talk about as a hardened atom going to talk about it as a proton the nucleus of hydrogen because what a harder datum is a proton and an electron and it's the proton that's that's important here that proton in the bond which is holding two molecules together likes to sit closer to one side than the other in fact it can sit on on either side what it doesn't want to do is sit somewhere in the middle because that's no good for it it's most comfortable energetically to be on one side or the other and it's known that that proton can sometimes jump across but to do that it has to quantum tunnel it has to sort of punch through a force field but it does that occasionally and and you can you can see that process and chemists have studied it very well okay so this is the shape of what's called the energy surface or the potential surface it's like it's imagine it's like a imagine a ball you have two wells – – two dimples two holes and you have a ball sitting in one of them that ball can't jump into the other hole unless you give it another another kick to knock it up over the hill over the barrier to the other side quantum tunneling would suggest that it doesn't need enough energy to get over the barrier it can just sort of somehow magically tunnel its way its way through it's been suggested the quantum tunneling might take place inside DNA did the two strands of DNA are held together by hydrogen bonds DNA the quickl what's the model of DNA is of these nucleotides these complicated molecules that come in four different types adenine thymine guanine and cytosine and they stick together in particular pairs so a sticks to T G sticks to C and they're held together by hydrogen bonds a very famous paper well actually it deserves to be more famous such as a famous in my world gyms world suggested that how proton tunneling might take place in DNA so here we have a picture of two of these nucleotides a and T held together by a pair of hydrogen bonds and energetically it the most favorable position is for that so the protons are labeled here by the H that the dots are electrons the so one HS city on one side and the other protons sitting on the other but every now and again occasionally tiny fraction of the time they could quantum tunnel across and sit on the other sides and you get a slightly different form of these nucleotides these bases what's called the tautomerize form now if the DNA strands you get this quantum telling and they split apart where these nucleotides are in the tautomerize form when the DNA replicates so you get another strand made of the surrounding material forms you won't get a T being able to stick to the tautomerize form of of a it'll it'll require a C rather than a T so what you get is a mutation a change in the structure of DNA if this proton tunneling takes place this was suggested 50 years ago this year it was suggested by a Swedish physicist by the name of pearl off Loudon and he wrote a paper called proton telling in DNA and aspera biological implications and he suggested that you know there are many mechanisms that cause that lead to mutations whether it's copying errors whether it's ionizing radiation coming outside hitting the DNA there's lots of very complex reasons why a DNA might mutate but he suggests that one possible mechanism would be quantum tunneling the other lovely thing about this paper is in the very first paragraph he says the electronic and protonic structure of biologically interesting molecules and systems has to be treated by quantum chemistry this has the opening of a new field which has been called sub molecular biology or quantum biology so I just wanted to let you know that quantum biology we're celebrating its 50th anniversary this year but nothing much has happened in terms of verifying or dismissing Louden's mechanism so this day we don't know whether quantum tunneling is a mechanism that that can lead to mutations we know that a proton in a hydrogen bond if given enough energy and there's a lot of energy that surround inside living cells it can jump over in from one side to the other but we also know that it's possible according to the rules of quantum mechanics that it can just tunnel its way through to the other side we're currently carrying out calculations to see because chemists do these sort of calculations for complicated organic molecules all the time I what I want to say very briefly in the last 10 seconds is that we're starting tentatively quantum biology to some extent is speculative but it's a new field we want to be able to take one step at a time quantum tunneling is one of those processes that is respectable that all that quantum chemist know takes place inside organic molecules let's see if we can design experiments biologically if we can do the calculations theoretically to find out once and for all whether at least quantum tunneling takes place in in biological systems mice this is my second to last slide just thanking my collaborators working in this field actually we had a workshop on quantum biology at the University of Surrey a few months ago I know about 40 or 50 people there and I asked one of the the the quantum biologist who'd been in the game for about a decade and I said what would happen if a bomb were to land here blow up this workshop we said welcome to biology would cease to exist as a field for a few years because if this is it this is everyone you realize this is a very small emerging field it's speculative but the payoff is one it would be huge if some of these processes turn out to be true and I leave you with my busy montage of of quantum biological stuff thank you