What keeps the universe in balance?

0:00This BBC podcast is supported by ads outside the UK. This is summer at its peak. Whole Foods Market Summer Fruit Fest is your invitation to eat the season. Fresh, organic, and bursting with flavor. Start your day with peaches and organic blueberries and yogurt. Build a grazing board with fresh fruit, prosciutto, and artisanal cheese. Then fire up the grill with no antibiotics ever proteins and fresh produce. Savor the season. Shop Summer Fruit Fest at Whole Foods Market. Chicago talks a lot. Hold on, let me step over here. People are talking too much. We debate about food, deep dish, tavern style, who's got the best beef.

0:41We yell across rooms, across blocks, across generations. Yes, nice earrings, Grammy. And now we're doing it on our phones, too. Video calls from the L train, group chats that never shut up. Neighbors texting you the score before your TV catches up. Come on! Get a load of this guy. Catch up on a dog. Yeah, we've got thoughts. Too loud? In Chicago, you're gonna hear it. Because nothing here gets built without conversation. Nothing moves without connection. So, if you think you know AT &T, it might be time to rethink that. Because their network has improved, like, a lot. So Chicago can keep speaking its mind with AT &T Wireless and AT &T Fiber.

1:21Chicago won't stop talking. Our improved network backs it up. AT &T, connecting changes everything. AT &T Fiber, limited availability in select areas.

1:36Welcome to Kakumu National Park. My name is Kwabina Asante. From Abrappu Dumasi here, who works as a tour guide in Kakumu National Park rainforest. We're hoping to see some stars. Where are we going? We are going to the forest, but the problem is the forest canopy will cover us to find a place where we can go up on the tree platform to be able to see the stars. Yeah, okay. Let's go. Yanko. Okay. You've caught me somewhere, unexpected, hiking through a forest. I found myself in Kakum National Park in Ghana's central region. It's the end of the day. All the visitors have gone home, and dusk slowly approaches.

2:27My guide, Kovana, is leading us into the forest. Do you believe there are spirits? Yes. Yes. Where we are in the nature. Yes. Each and every tree has its own spirit to protect us. Without them, we cannot live. That's why we normally say, when they last, the last man dies. I'm here to see some stars. And that's not easy with a dense canopy overhead. So we've got a little hike ahead of us. If I'm going to have any chance of seeing the night sky, we'll need to make it to a bird-watching platform built around a huge tree, which is slightly more difficult to find when light's fading. It's getting dark, so let's hope to see something.

3:15What was that? So I would say that don't be scared. We're here, we are in the nature. Nothing to be scared of. The only thing I'm scared of is failure. And cobras.

3:36You're listening to CrowdScience from the BBC World Service. The programme that peers into the cosmos of your science questions to find the answers in the stars. I'm Alex Lathbridge. Today's story doesn't start in the depths of a rainforest, at the beginning of the universe, or even in the burning heart of a dying star. It starts at Makala Market, right in the middle of Ghana's capital, Accra, where hundreds of traders line the streets and shopfronts. And for the first time in my life, I'm not here just to buy designer sunglasses. I'm here to meet listener in Danusa. Everybody comes here. People land at the airport and say, I want to go to Makala because truly this is it.

4:20This is the centre of trade, commerce. I'm in Danusa Amate. I live in Accra. I am part Nigerian, part Ghanaian. I'm an engineer by schooling. To be honest, before I was born, I've been an engineer. I really like to say this. I engineered my way out of my mom. So, truly, I've lost science and engineering since I was born. So, what was your question? Because it was a really interesting one. My question was, if stars consume hydrogen and produce helium and other elements, should there not be something out there producing this hydrogen, therefore creating a cycle of balance? Okay, so this is one of those questions which seems simple at first, but the more you think about it, the trickier it gets.

5:06Danusa knows that the stars are fuelled by hydrogen, and he knows that this process produces helium too, and so he's wondering, Is there something out there which does the reverse, takes all that new helium and turns it back into hydrogen, so the stars can keep burning and everything remains nicely in balance? His idea makes sense. That's certainly how it works here on Earth. From my understanding of nature, everything exists in a cycle of production and consumption. Right here on Earth we can see that oxygen goes through a cycle of production and consumption, water, even we humans. We breathe in oxygen and turn it into carbon dioxide, while plants do the opposite.

5:50Water falls as rain, evaporates into clouds, and falls as rain again, round and around and around. Plants consume nutrients from soil, animals consume plants and then die, and put those nutrients right back where they came from, in the soil. Everything we see seems to exist in a kind of perpetual system of cycle and recycle. Ndanusa is wondering if the stars do the same. I want to believe that this law exists in the whole universe. Should there not be something out there that produces hydrogen that stars now consume? That's such an interesting idea. You're thinking about the universe here, but even here in Makala Market where you're working, this is a market that's known for buying and selling.

6:38So you're seeing that cycle there? Yes, I do. I see it every day. Imagine what would happen if there was a lot of buying by the shop owners and there was no selling. I guess the market will probably implode. So there's balance everywhere, I guess. So you have the idea that if hydrogen is being used up by our stars, then there's got to be something else making it. What do you think the answer might be? There has to be something equally as powerful and massive as a star. because producing hydrogen will require lots of energy, something massive enough to split the helium atom into two. So that requires a lot of pressure, a lot of pressure, a lot of energy.

7:18So that's what I have in mind for now. In the end, everything balances out. Stars need hydrogen. All I've ever heard was, hydrogen is the most common element in the universe. I've never really heard an explanation as to where this hydrogen comes from. I believe there's something out there producing hydrogen. And I would really like to find it. yeah all right and danusa we're on the case if the stars in the night sky are powered by hydrogen then where does it all come from if the stars burn through hydrogen to make helium as they do is there anything out there that does the opposite turning helium back into hydrogen to keep the universe in perfect balance i mean is the universe in balance at all To answer these questions we're going to wind back the clock, peer right back to the beginning of time, look up and down the length of the periodic table and gaze deep into space.

8:16Luckily only a couple of hours drive north from Makala Market in Accra there's something pretty special which can do just that. If you are on the highway you see them as very small and then when you drive up you see that this thing is just becoming big and big and big and big. It's the enormous curved 32 meter parabolic dish of the Ghana Radio Astronomy Observatory. And then when you see it moving then you begin to ask yourself what is it doing? So it's collecting the radio waves from space. Dr. Emmanuel Proven-Adzuri, an astrophysicist and the manager of the station here, was ready to welcome us at the gate.

9:01Akwaaba, welcome to the Ghana Radio Astronomy Observatory. It's beautiful. You can hear birds in the background. And of course, there's a giant radio telescope up there and it's pointing directly upwards. So is that to be able to see the stars better? Yes, yes. So in astronomy, the bigger the dish, the better. You've got a ladder on the side of it and I kind of want to go up and see the dish. So can you show me around? Yes, of course. Let's go. The enormous dish has a fascinating backstory. It was built in the 1980s as a satellite communication dish carrying phone calls between Ghana and the rest of the world.

9:41When fibre optics came in the early 2000s, it was abandoned and sat here unused for around a decade. A giant metal ear pointed to the sky, listening to nothing. So we are now on the elevation platform. Okay. I've made it. I'm not scared. Until astronomers across Africa started collaborating on an incredible project, converting telecom dishes like this one into radio telescopes, collecting data from the depths of space together as a network. They are going to work together in sync. So if you have dishes in Ghana, in South Africa, in Mauritius, Kenya, Namibia, Zambia, Botswana, In the future, we expect that all these dishes will observe the same astrophysical source at the same time.

10:35And then you correlate the data together in one big computer. And then you produce your image, some very super cool stuff of the universe. It's called the AVN, or to use its government name, the African Very Long Baseline Interferometry Network. And this one in Ghana was the first.

10:58so we're now inside what are we looking at so we are looking at the feed horn so the feed horn is the waves from space getting onto the big reflector that's the dish so this feed horn directs the waves into the receiver wow so that gap there i see that's where the radio waves come through this one is here it's a mirror and this is the last mirror that directs the re from its center straight through this place and into the receiver back down in proven's office we got stuck into some serious astrophysics the question that we had from our listener starts with the stars burning hydrogen so if we managed to wind the clock all the way back where did most of the hydrogen in the universe actually come from.

11:49So all the hydrogen in the universe started just after the Big Bang. And the conditions and the ingredients were there. It was very hot, very dense. And then the first element, that's hydrogen, was produced, followed by some helium and then some lithium. He's very much underselling this story, so allow me. Around 13.8 billion years ago, there was nothing. This was a rather boring and silent period in history, but then again, the concepts of sound, history and boredom didn't yet exist. This all changed in a fraction of a second with the Big Bang, our universe birthed from a single super-dense point in spacetime.

12:35Within a cosmological heartbeat, there was something, and there was a lot of it. These weren't elements by any means, rather a hot dense plasma soup filled with fundamental subatomic particles, your electrons, protons and neutrons. Over time, which very much existed at this point, those particles began to fuse together into the very simplest atoms. Just one proton and one electron gave us hydrogen, the lightest element in the universe. us. Following that, helium with two protons and two electrons. Our periodic table remained relatively empty with just two elements and then three with some small amounts of lithium soon forming.

13:21As the universe expanded over millions of years, this soup cooled enough to bear something special. The first stars were formed through gravity and then the collision of these hydrogen atoms. They're pulling each other together and then they start to spin, getting more dense, getting more momentum, pulling in more materials. And then they begin to collapse under their own gravity. Then you now begin to start the nuclear fission that begin to bend the hydrogen. A star is basically a giant nuclear reactor squashing atoms together under enormous pressure until they fuse together. For most of a star's life, it fuses hydrogen to helium.

14:05That's what our sun is doing right now. But it doesn't stop there. Bigger, older stars, which are even denser, fuse that helium into heavier elements. From helium, you have more heavier atoms coming out. Carbon, oxygen, and then later ion. That's the process of this nuclear fusion. So from the Big Bang, we had hydrogen within minutes, and then these heavier elements took millions of years. Why? It's a rather long and steady process happening in the stars. One lighter element will lead to the next heavier element, and then you begin to have the more heavier elements. It's an interstellar domino effect.

14:51Fusion works down the periodic table. Carbon to neon to oxygen to silicon, all the way down to iron, which is the heaviest element that can be forged in the heart of a star. We're around a quarter of the way down the periodic table now, and so far, it's a lot of production and consumption, but none of the recycling that Listan Danusa was expecting. So the stars are like the factories where all these elements are coming from. Sometimes I liken it to the way crude oil is refined. Yeah, you see crude oil as very black, dirty stuff. But when you pass it to the refinery, then you begin to have several products coming out, your petrol, even your fertilizer materials all coming out of it.

15:37So it's a really nice factory where all these things are being produced. All right, and sort of bring it back to listener Danusa's question. Are there any processes in today's universe that can go backwards, that can convert helium into hydrogen? The short answer is no, because you need enormous amounts of energy to convert the helium back into hydrogen. And the amount of energy should be much, much higher than what is going on in the stars. There's no amount of system that will give you much more energy to now convert this helium into hydrogen. Is there new hydrogen being produced anywhere in the universe?

16:20No, no. All the hydrogen that is there now is what was created just after the Big Bang. So new hydrogen is not being created. So the time will come, the universe will actually run out of the hydrogen that is formed at the beginning of the Big Bang. But that is still a very long way, trillions of years. So does that mean if we can't take helium back to hydrogen, then the universe isn't a system that recycles these elements? The universe is more like a chemical evolution and you can picture it like a one-way street. It's not going back the other direction. But you also need to remember that though our Earth is a closed system where things are being recycled, in the timeline of the universe the sun's energy is going to run out and the sun may explode the earth is also going to be turned into something okay so us humans is just a fraction of a moment so we're just a fraction of a moment our earth is just a fraction of the whole even if you compare the earth to the solar system very small fraction then compare the solar system to the whole universe in the timescale of the universe our earth though you see it as a very nice recycling plant it's also going to end up into something yeah so when we're looking up at the stars we see a universe that feels uh feels eternal in perfect balance but if we're really slowly burning through all the hydrogen in the universe it sounds like we're not actually in balance at all it sounds like the universe is very slowly burning out.

18:00Yes, that's it. The stars are slowly, steadily burning this hydrogen. That's balance in a way, yeah. Okay, so according to astrophysics, there's nothing in the known universe that acts the way Indanusa was hoping, a sort of anti-star, unfusing helium back into hydrogen to give the stars enough fuel to keep burning forever. And so this means that, yes, all the stars in the universe, including the one at the center of our solar system, are burning through all of their fuel. One day, they will run out, cool, and die. There's no recycling like we see here on Earth. But is that the end of the story?

18:46That's what we'll find out next. This is summer at its peak. Whole Foods Market Summer Fruit Fest is your invitation to eat the season. Fresh, organic, and bursting with flavor. Start your day with peaches and organic blueberries and yogurt. Build a grazing board with fresh fruit, prosciutto, and artisanal cheese. Then fire up the grill with no antibiotics ever proteins and fresh produce. Savor the season. Shop Summer Fruit Fest at Whole Foods Market. Chicago talks a lot. Hold on, let me step over here. People are talking too much. We debate about food, deep dish, tavern style, who's got the best beef.

19:26We yell across rooms, across blocks, across generations. Yes, nice earrings, Grammy. And now we're doing it on our phones, too. Video calls from the L train, group chats that never shut up. Neighbors texting you the score before your TV catches up. Come on! Get a load of this guy. Catch up. On a dog. Yeah, we've got thoughts. Too loud? In Chicago, you're gonna hear it. Because nothing here gets built without conversation. Nothing moves without connection. So if you think you know AT &T, it might be time to rethink that because their network has improved, like, a lot. So Chicago can keep speaking its mind with AT &T Wireless and AT &T Fiber.

20:06Chicago won't stop talking. Our improved network backs it up. AT &T, connecting changes everything. AT &T Fiber, limited availability in select areas.

20:20you're listening to crowd science from the bbc world service where the burning stars of your curiosity light up the night sky of ignorance i'm alex slathbridge and i'm trying to find an answer to a question from indanusa from ghana who's curious about the energy that powers the stars and what happens when that energy runs out. So far, we've learned a lot about fusion. So could there be a way to reverse the fusion process, make new hydrogen, and keep the universe ticking along forever?

20:57Back in Kakum National Park, we've reached our destination before the torch drained my phone battery. Built around a colossal tree, a huge 40-metre wooden tower rises up above the rainforest canopy. The darkness has truly taken over. In the distance, a hyrax is calling, and the stars are beginning to show themselves in their tens and hundreds.

21:30We're getting a great view. Surrounded by the sound of nocturnal creatures and atop the rainforest canopy, the stars seem so much more meaningful than giant nuclear fusion machines far away in the universe. Kwabana and Chris, another guide here, tell me that I'm not alone. If a star moves, it will fly like going to fall somewhere. They will tell you somebody is going to die. That's what they were telling us. The stars in the skies are representing humans. So if you see any of the stars moving, it means you are going to lose somebody. Or a human life is going to get lost. It's like people don't want to listen to their grandfathers, their grandbanders anymore.

22:22But formerly because there were no lights in some communities, no electricity. So when the moonlight comes up, they call all the children together and sit down and be telling them stories. When you were a child, did you grow up sitting down hearing stories on the moonlight? Yes, I was. It was my grandfather, my grandmother was doing that work. I can remember some of the stars, they were even giving names. There's a particular one star, it shines, but it does the moon as the moon is moving. Now people are not concerned about the stars. Those stories are going away from us. It was even good for eyesight.

23:08If you don't have a good eyesight, you don't see that star more. That's your test, your eye test. Our forefathers told us that if you count the stars, you are going to die. That one I think is true, because you can't count them. How can you count all these stars? Very difficult. One, two, three, four. You get confused. So they told us, if you try counting the stars, you are going to die. So you will not try at all.

23:36If you ask me there's heaven, I'll say no. If there's hell, I'll say no. Heaven's where we are standing now. That's my belief.

23:53When most people gaze up at the twinkling stars, they might make a wish. But listener Danyusa worries about their fuel consumption. he's an engineer through and through he wants to know what keeps the stars burning and whether the elements that make up our universe get replenished or recycled so that they'll never burn out so far it looks like the answer is no stars use up their fuel mostly hydrogen by fusing it to make heavier elements. And all the astrophysicists agree, nuclear fusion can only go in one direction. But is there an alternative? In terms of fission, you want to break the elements apart.

24:39We've come 250 kilometers north to the city of Kumasi and to the Kwame Nkrumah University of Science and Technology, the premier science university in Ghana, a school that I did not get into. After producer Emily and I got lost on the campus and somehow ended up in an undergraduate geophysics lecture, we were able to find a man who knows a lot about how the universe is arranged. I'm Dr Linos Kwekulabek. I am a physicist at the Department of Physics. My research area is into protoplanetary disks. Protoplanetary disks, basically, when stars form, they have their dust switches around them. They would coagulate and then form into planets.

25:19And basically, I want to understand how they form into planets. More on protoplanetary disks later. I'm here so that he can explain a technology which does just what Ndanyusa was wondering about. It breaks atoms down from larger to smaller. You've probably heard of it. It drives the generators in nuclear power plants and shook the world with the bombs dropped on Hiroshima and Nagasaki. It split the atom, fueled the Cold War and changed history forever. It's called nuclear fission. Not fusion, fission. Fission. Fission? Fission. Yeah. It's difficult. So what is fission? Yeah, so fission, that's the F-I-1.

26:04So nuclear fission is when the particles in the nucleus, the protons and then the neutrons, which are together, would break apart. Why would humans actually want to do this process of nuclear fission here on Earth? For energy processes. Most of the nuclear reactors we have on Earth are basically tuned towards nuclear energy. Ghana, for example, is interested in nuclear energy so that they'll provide enough energy for us. What elements are usually involved there? So you tend to do that for heavier elements, materials like uranium, which are able to be broken apart into smaller elements. And that is what you have in a control system here.

26:43And so why is fusion then so common in the universe, while fission is comparatively rare? So fission requires a concentrated amount of material. And in space, you do not have that. In terms of uranium in the universe, we do not have that much of it there. So even if you notice, even on Earth, we need to do some kind of uranium enrichment to be able to create the processes for fission. Splitting the atom is undoubtedly one of the crowning achievements of human science and technology. Out there in the depths of space, it rarely happens. But let's get hypothetical. Could this process be used to split helium back into hydrogen?

27:27Could this be the thing that Ndanyusa was searching for? Can we go from helium back to hydrogen? In stars, it's going to be impossible to do that because for fission, it's a chain reaction. So once you do not have that chain reaction, then that means you cannot have fission. So it's quite difficult for you to have that process. Right, okay. It's like pushing a snowball down a hill. You do the initial push and then it sort of takes care of the rest. The process keeps going and going and going, right? Okay, so from cartoons, I've watched snowballing and I think that is right. Yeah. Yeah, I've watched cartoons.