The Fifth State of Matter

Scientists from the University of Nottingham have developed a material that stops fungi from growing on surfaces. Welcome news for those who have ever had to clean black mould out of their bathroom! They use polymers that can be 3D printed, and that are designed to tackle a wide variety of damaging fungi - from human pathogens to crop diseases. Unlike fungicides, which can be toxic, these materials appear to be safe at least for plant use - and given that fungal infections are responsible for around a million and a half human deaths worldwide every year, could end up being much more widely useful. Simon Avery helped lead the research, and spoke to Chris Smith...

Simon - Well one of the problems with fungicides or antifungals is these can kick around for a long time, and there are environmental concerns around that. There are tight regulations - and the regulations are not easing, they're tightening - about the use of these fungicides. And also fungi, like bacteria with antibiotics, they can develop resistance.

Chris - And therefore you wanted something that was safe for widespread use, would surmount the problem of growing resistance, and could be easily used?

Simon - Well yes, we were interested in developing a method that didn't involve killing action, because that's where this toxicity and environmental concern comes in. We were interested in actually blocking what is usually the first step of most of the problem that fungi cause, and that is attachment. To cause disease, or even to grow between tiles and grouting in bathrooms, they need to attach to a surface first. If you can block that, then in principle you can block the subsequent problem.

Chris - So is this antifungal equivalent of Teflon, nonstick surfaces, then? You've got something you can put onto a surface, and it just means that if any fungus did try to land on that surface, it can't gain a toehold and therefore it can't start to proliferate or grow?

Simon - I quite like that analogy.

Chris - What is the actual chemical itself? How have you done this, and will this work on a slice of bread as well as it will work on a bathroom tile?

Simon - Well, the chemical... we have a few of these polymers which appear to be very effective. A slice of bread presents a more challenging surface. And also of course, then it's directly onto food, and so there are other challenges there. But we've tested plant surfaces, and they work effectively on those; and glass; plastic surfaces; 3D printed parts we've made as well...

Chris - And does this work against the whole repertoire of fungi that a bathroom tile,, right through to the ear of barley or wheat, might encounter; or is it horses for chemical courses, we're going to need different types of treatment for different indications?

Simon - We've been testing about five different types of fungi: human pathogens, crop pathogens, and the types of fungi you find around the house. The same material won't necessarily work for all types, but then you wouldn't want the material to be usable in that way. There's no reason if you're using it on a crop for it also to give resistance to human pathogens. But we have found materials which work against two or three of the five fungi that we've tested. So that's particularly promising

Chris - What's to stop the microbial world doing what it does best and evolving to just sidestep the blockade imposed by your new chemicals?

Simon - Yeah, it's a good question. If with an antibiotic the bacterium doesn't develop resistance, it will die. So there's a strong, strong pressure on the bacteria to develop resistance. With this, because we're not killing, there's a much lower pressure. And so we anticipate - and we've started these sorts of tests - that the evolution of resistance will be much, much slower, if it happens at all.

Chris - And safety? Because one of the other major considerations is safety in terms of, if you're going to put this on something people are going to eat, that's a major consideration; but also environmental safety, if we're going to be spraying this sort of thing on crops, can you reassure us that these are potentially safe treatments?

Simon - We don't expect, and indeed we've not seen, significant toxicity. And in fact, in humans these have a long track record of safety. One of the advantages in humans, if they're used in humans, is that they don't degrade, and so they don't release potentially toxic products; but in the environment of course, ultimately you would want them to degrade. Modifications can be made, and we've been planning some of those to make these more biodegradable if it's needed for a particular application, such as crop sprays.

On the 30th of May, just after 7.20pm GMT, a SpaceX rocket launched two NASA astronauts into orbit. They’re now safely aboard the International Space Station. 10 million people watched the launch live - the first time ever that a private company has flown humans into orbit. To find out what that might mean, Katie Haylor spoke to BBC science and environment correspondent Victoria Gill...

Victoria - The cool thing about this particular spacecraft, about the Crew Dragon capsule, is that that whole journey was fully automated. Basically the capsule's kind of pre-programmed, it knows its way to the International Space Station. So the plan was for the two astronauts, Bob and Doug, to not do anything, they would just have to sort of monitor all of the systems. Then the plan is for the future for it to operate like a space taxi. They even talked about being able to get some sleep while they were on their way up there. So it appears that all of the instruments in the navigation and everything that was automated worked as it should.

Katie - Wow, so it went pretty well then!

Victoria - Seems that way, yes. If you've watched any of these test launches, there's just cameras absolutely geared up to watching and sharing, and kind of bigging themselves up to the whole world. So it's an incredible thing to watch. But one thing that you could watch was the astronaut’s-eye view from inside the capsule. And it's interesting because the instrumentation panels are all just touchscreen. These spacesuits were designed with the help of Jose Fernandez; he designed some Hollywood costumes for some of the superhero comic movies, and so they look pretty much like that. They look very futuristic and kind of strange, and they've had a lot of attention. Their gloves are actually touch screen sensitive. So it was quite an amazing, pretty futuristic looking view from inside the capsule. And it just seems to have gone very smoothly and even docked automatically as well.

Katie - If it's automated then are the astronauts kind of practicing when they're in there? Do they... I'm guessing they need to know how to take over in the event of an emergency, right?

Victoria - Absolutely that. They need astronauts on board that are going to be able to take over and manually operate this space capsule if anything goes wrong.

Katie - How significant is it that this spacecraft was commercially made?

Victoria - I was actually speaking to Tim Peake, British astronaut who was like most of us locked down at home, watching this launch very excitedly and nervously over the weekend. This was the start of a new commercial era in space travel, as he was telling me.

Tim - Since the shuttle retired in 2011, we've been relying on just the Soyuz rocket. And whenever you have a space program you don't want to rely on just one vehicle. I mean, in that period of time the Soyuz has had a couple of problems and it's left us in a very vulnerable situation. So now we have redundancy, which is great. But also, of course, last night's launch and the success of this mission will pave the way for Europeans to be able to go to space on that vehicle in the future.

Katie - Are there other players besides SpaceX at this kind of level?

Victoria - So the two main ones now are SpaceX and Boeing, and for the European Space Agency, the next flights for their astronauts are going to be hopefully aboard the Boeing Starliner. This is a big contract and a big point in an important commercial relationship between NASA and SpaceX. So 2.6 billion pounds transportation contract, that basically means that they can get astronauts to the ISS and hopefully back from the ISS; obviously that's the next part of the round trip. But it's significant that SpaceX got there first. And I think Elon Musk, enigmatic tech billionaire that he is, was crowing reasonably loudly about that.

Katie - Is the idea to reuse this system?

Victoria - That is a big USP for SpaceX, is reusable rockets. And it's been something that Elon Musk has been very vocal about: that space travel, as mindblowingly expensive as it is, a lot of money can be saved if we're not just throwing away these incredibly expensive propulsion systems. That's a big part of what they want to do. And they do seem to have been successful at least in testing it. So now they can move forward into fulfilling the part of that contract where NASA get what they want out of it, which is basically the time and resources to spend going, as Tim Peake says, beyond to the moon and to Mars.

Tim - What the national space agencies would like to do, of course, is to slowly hand over operation of the entire International Space Station to commercial companies, and for them to be a customer themselves. So SpaceX is a model which we're using to try and embrace for low-Earth orbit. And what that does is it frees up the space agencies to go on with exploration to the moon and Mars. So we've already taken that same partnership that we have with the International Space Station, and that same group of nations are planning a new space station to go in orbit around the moon, which will help to facilitate lunar landings in the mid to the late twenties.

We're celebrating the 25th anniversary of a Nobel Prize-winning achievement: the creation of the 'fifth state of matter', a bizarre soup of particles that’s known as a Bose-Einstein condensate. It’s one of the more complicated concepts in physics, but that very complexity is what makes it mysterious and exciting - with implications for quantum computers, dark matter, and the very fabric of the universe. Where does this idea come from? Chris Smith heard from two Bose-Einstein condensate physicists: Lindsay LeBlanc from the University of Alberta, and Rob Nyman at Imperial College London...

Rob - Satyendra Nath Bose was an Indian mathematician who made some realisations about the statistics when you count the ways of arranging identical particles. In quantum mechanics, there's a particular concept of identical particles. So identical that you couldn't stick a label on them, even in principle. And that's what Satyendra Nath Bose realised. And he tried to get his work published. He wrote to lots of journals and they all said no, because they didn't understand his work. And eventually in despair, he wrote to Einstein and said, "can you please see if you understand it and maybe get this published?" And Einstein immediately understood it, and did some calculations himself and realised that one of the consequences is Bose-Einstein condensation. He translated the paper into German and helped get it published in a German article.

Chris - And how long ago was that?

Rob - Satyendra Nath Bose wrote to Einstein in 1924, and Einstein published his article in 1925.

Chris - So this is another example of work which was theorised almost a century ago, but has taken until almost the modern era and technology to catch up so we can actually start working on the ideas that these people had?

Rob - Absolutely. It's a simple idea, where Einstein had a thought experiment about simply adding a few more particles to a system. And they all collapse into one state, which is the essence of a Bose-Einstein condensate. He had that idea, and it took 75 years before we could actually make them into a real experiment rather than just a thought experiment.

Chris - As I mentioned, Lindsay LeBlanc is also with us. Lindsay is at the University of Alberta, she works on this too. Lindsay - what actually is a Bose-Einstein condensate, though? If we were to actually see one in a dish, what would it look like?

Lindsay - Well for first thing, it's quite small. And so you need a microscope of sorts to see it. It's a collection of atoms where all of these atoms are no longer individual particles anymore. They become almost like a super atom - they all behave together. They work together and they create this sort of new quantum soup that has different characteristics than the other kinds of matter that we know about.

Chris - Now, when you say that they all behave as though they're one - when we're just got individual atoms, they would just be buzzing around all over the place, going in random directions. How do you actually turn them then into a Bose-Einstein condensate so they behave as though they're just one atom?

Lindsay - The first thing that we need to do to make a Bose-Einstein condensate is to make them very cold. The ideas of quantum mechanics start to emerge when things are cold, because we are able to get rid of the randomness associated with temperature. So we think of hot things as, exactly, buzzing around in a random way. To get to the Bose-Einstein condensate, we need to get rid of that randomness. And so we need to cool the atoms down to very low energies. And this comes back to the original ideas of Bose and Einstein, where: why does this happen? It happens because the world is quantum, and we could only see this at these very low energies when things are very cold.

Quantum means that there are discrete levels. And so you can have, say, zero, or one energy unit, or two energy units; but you can't have like 1%, you can't have just a little bit, you have to have either zero or one. And so if you get cold enough, suddenly these particles don't have enough energy to be in that first energy unit. They have to be in the bottom one. And so they're all acting together in this condensate. Experimenters like me and Rob in the lab, we have to figure out ways to get those atoms that cold. And that was really the technical achievement that was made possible by lasers and all the developments through the 80s and 90s that brought us the first Bose-Einstein condensates in the lab.

Chris - And Rob, when we actually think about the way these things are behaving, are there any good sort of analogies that you can give me, which would enable me to imagine atoms all behaving as though they're one giant atom instead of a collection of atoms?

Rob - Yeah, I think probably the clearest analogy for me is that a Bose-Einstein condensate is to an ordinary balloon full of gas, as a laser is to a light bulb. Very, very intense and everything is moving together. So lasers come in beams; light bulbs spread out. And lasers can be much brighter than light bulbs. Just like Bose-Einstein condensates can have high densities, but also the particles move together.

Chris - And Lindsay, when we get down to this low temperature and we make atoms get into this configuration, what sorts of properties do they have that get physicists like you excited?

Lindsay - The fact that they are quantum particles, but there are many of them means that I can work with them. So they're big enough that as an experimentalist, I can do something useful with them. There's many different things that people have figured out what to do with them over the last 25 years. Some examples include quantum memory, which is something we work on in my lab. We take the atoms and we use their quantumness to store quantum information, which is very much related to this revolution in quantum computing that is going on around us. We're able to use the quantum properties of this macroscopic object, to grab onto information, hold onto it and then retrieve it sometime later. So it's almost like RAM or a hard disc for a quantum computer. Other applications include generally understanding the fabric of our universe. So this is a quantum object that we can manipulate, that we can study, that we can take pictures of. And what we can do in the lab is sort of poke and prod it in different ways to see what happens to quantum objects under these conditions. And so we use these condensates as a simulator of other quantum systems to learn more about how many body quantum systems act in a variety of contexts.

Imperial College London physicist Rob Nyman is making Bose-Einstein condensates out of photons, particles of light. Chris Smith asked him how it works...

Rob - The wonderful thing about the prediction of Bose-Einstein condensation is it doesn't make any particular comment about what kind of particles they are, other than that they have to be rigorously identical to each other. As long as you can make rubidium particles identical to each other, in combination with coldness and denseness, you can make them into a Bose-Einstein condensate. And the same is true of particles of light: photons. But making them cold and dense is the hard thing. Cold turns out to be a relative thing, and for photons cold can be room temperature, if you could only make them come to equilibrium without them disappearing. So we have to trap them somehow. And the way we trap photons is between a pair of very high-reflectivity mirrors, perhaps one millionth of a metre apart.

Chris - So let me get my head around this then. You put some light between two reflective surfaces. How do we then turn that into something that's cold? How can light have temperature? ‘Cause surely if it's got energy, it's got temperature; and light is energy, isn't it?

Rob - This is true. We have a problem that actually the matter around us emits and absorbs light and it does so in a somewhat randomised way. And if we tried to cool a black box down - that’s the way we typically describe it - it would simply decrease the number of particles. And so we wouldn't... while it gets cold, the density would get low and we'd never achieve that high density and low temperature. So we have to do a special trick, which is we put a dye, a fluorescent dye in between our mirrors; literally the same kind of dye you would use in a fluorescent highlighter pen. And the light is absorbed by the dye and then re-emitted. And the combination of absorption and emission, this exchange of particles with a reservoir of matter; that allows the light to come to thermal equilibrium at room temperature, without the number increasing or decreasing. And now we can just change the number. The way we do this is we essentially shine an overpowered laser pointer at our pair of mirrors until the density gets high enough that the combination of density and temperature is now appropriate to make a Bose-Einstein condensate.

Chris - If you make one of these, what does it actually look like?

Rob - So the images of photon Bose-Einstein condensates in my laboratory look like a kind of a fuzzy spot around, which is mostly greenish-yellow, and in the middle is a bright yellow spot. The greenish fuzz around is what we call the thermal component and the bright yellow spot is the Bose-Einstein condensate in the middle.

Chris - Now Rob, you've done this with photons, these are packets of light; but there's also these notional graviton particles that enable gravity to be conveyed from one body to another allegedly. I mean we've got no proof of them, have we, but would they potentially also therefore form a Bose-Einstein condensate? And if they did, what would it look like?

Rob - In principle? Yes. One could form a Bose-Einstein condensate out of any particles, which first of all need to be rigorously identical, like gravitons, the particles of gravity. And secondly they need to be brought to thermal equilibrium without their number increasing or decreasing. How one would bring gravitons to thermal equilibrium, I'm not clear; I don't see a particular configuration, but I don't see any reason why one couldn't either. If one could, then what they would look like would be a very large scale wave of gravity. Very much like the gravitational waves emitted by for example, orbiting black holes.

Chris - In your experiments, the thing that I'm slightly struggling with is how you manage to make sure that your light doesn't soak into the mirrors, give up its energy and just disappear. And also how you don't end up with the mirrors being warm enough to add just more photons of their own and confuse your results. How do you keep it clean?

Rob - They are extremely good quality mirrors. They reflect something like 99.997%, which means the light bounces around perhaps 30,000 times before it is eventually transmitted through the mirrors. That's enough times for the thermal equilibrium processes of absorption and emission with the dye to happen. So all that matters is that the mirrors are good enough, and in this case, it turns out to be about as good as you can get them buying it from the very best company who can make these things.

Chris - And while it's lovely, what's the point? What are we learning by doing this? And what might be the application of being able to make these photon based Bose-Einstein condenses?

Rob - One of the points is that Bose-Einstein condensation is a phase transition in very much the same way as a vapour can condense to a liquid. That's why it's called condensation. So we can use photon Bose-Einstein condensation to understand what a phase transition is. That's revisiting textbook definitions, reunderstanding, but that's still very academic. The other thing is I'll maybe turn your question about applications backwards. And it turns out that there is circumstantial evidence that photon Bose-Einstein condensation is happening inside devices called VCSELs: vertical cavity surface emitting lasers. Now they sound esoteric, but there's one of those in pretty much every single computer mouse. So it's not absolutely sure, but it seems like photon Bose-Einstein condensation has been going on in billions of devices for a decade and more now. And we just haven't realised it.

To create a Bose-Einstein condensate normally requires equipment that takes up a whole room. But a couple of years ago, NASA’s Cold Atom Lab managed to blast the whole setup up to the International Space Station - and they’re now starting to get exciting experiments underway. Phil Sansom heard from Rob Thompson, the project scientist in question...

Rob - We have built an apparatus that will allow scientists to study ultra cold matter in the microgravity environment of the International Space Station. So we're making Bose-Einstein condensates in space.

Phil - That sounds, on the face of it, super cool.

Rob - Both literally and figuratively, I think, yes.

Phil - Why? What's the point?

Rob - What's the point? Gravity affects these types of experiments. People are doing these on the ground, but almost every terrestrial experiment has at least some sort of effect of gravity that limits how long you can look at the atoms. For experiments that really are trying to reach the ultimates in sensitivity and so on, those types of experiments will benefit by going into microgravity.

Phil - Can you make it concrete for me? How much longer, for example, can you get a Bose-Einstein condensate to last in space compared to on Earth?

Rob - Sure. Ultimately the limits are simply how cold you can get them. The colder the cloud is, the slower a gas will expand, and the longer we'll have to look at it. In our experiment, we're aiming for about five seconds. As far as I know the record on Earth is about two seconds.

Phil - Does the fact that space itself is so cold help with the fact that you need to cool this stuff super cold?

Rob - No, it doesn't. Space while it's super cold, is a couple of degrees Kelvin above absolute zero. And the temperatures that we're trying to achieve are below a billionth of a degree above absolute zero. So while space is relatively cold for most of us, in the context of this experiment, it's actually really, really hot.

Phil - Is it the astronauts up in the ISS that are controlling this and doing the experiments?

Rob - Oh, so we run the experiment entirely from Earth. Basically we can connect up to it as if we're connecting up to a machine over the internet.

Phil -  What are you hoping to achieve with your sci-fi space Bose-Einstein condensate lab?

Rob - I really would like us to achieve the goals that our science teams are looking at, because I find them just amazing. Several of the teams are focused on atom interferometry, this ability to use the wave-like nature of atoms to make these incredibly sensitive quantum sensors. And one of those teams is going to test Einstein's theory of general relativity, and also to search for certain candidates for what is dark energy.

Phil - Why should anyone who's not a physicist care about this?

Rob - These are questions, I think that ultimately, are important for humanity to think about and have answers to, but there's also a lot of more practical, potential applications. We can use these atom interferometers as navigation, for spacecraft navigation and exploration and so on. We can potentially use them to help monitor the effects of climate change. As you have things like ice sheets melting, those change the local gravity of Earth in that area. I think there's always this thing that you learn from basic science, basic physics; it always kind of surprises you that it ends up being profoundly important.