Q&A: Defining AI, Dark Energy & Dr NO

Making your own sourdough bread starter may have been a big trend when everyone was spending more time at home due to the pandemic, but using yeast to make bread rise has been around for centuries. Rob Dunn chats with Chris Smith...

Rob - The crucial ingredient in sourdough is actually a mixture. So, it's yeast and then different species of bacteria. And so the yeast are producing carbon dioxide, which makes the dough rise and the bacteria are making it sour and producing all sorts of lightweight chemicals that add aromas and flavours. But the first use of yeast goes back certainly 14,000 years. It probably was first used to ferment in China. And then spread to the fertile crescent and then spread around the world from there. And so we've been using it for a long, long time.

克里斯- How do you know, 14,000 years? That's a very long time.

Rob - Well, so that's the oldest piece of bread anybody's found. The oldest beer is about the same time period. And if we look at the yeast, the evolutionary tree, we also see, sort of a branching in the tree that more or less maps to that same period of time. Probably as we make more discoveries that time will push back farther and farther. And we're starting to think that some of our other ancestors may have fermented things. And some of the evidence comes from capuchin monkeys. And some capuchin monkeys appeared to have learned how to knock down fruits that they can't eat. And then to come back to them three or four weeks later after they've rotted and become kind of like a "simian kombucha".

克里斯- Right? So they knew that this was a way of converting the in digestible into the digestible.

Rob - Yeah. They figured out a series of steps that allowed them to produce a new product

克里斯- When we consider yeast. I mean, I presume we as humans have exerted some degree of sort of evolutionary pressure on the microbial world, including things like yeasts to make them do those sorts of jobs better for us, become better yeast for brewing, become better yeast for baking.

Rob - We know that we've tended to favour brewing yeast that are able to survive the presence of lots of alcohol. But we also know that yeast when it was moved around the world, that it was under different selective pressures in different places because people used it to make different things. And so what we're starting to see is depending on where you look, you see different varieties of yeast in the same way that you might see different kinds of tomatoes. And then on top of that, what we've seen recently is that the industrialization of bread and beer production is favoured by varieties of yeast that aren't so good at producing wonderful flavours, but they're just really good at being consistent and working in an industrial context. And so that's a really strong selection pressure that's recently been documented, but it's a big evolutionary story. It's like Darwin's finches, except at the end you get beer.

克里斯- It's my favourite example of synthetic biology that is the brewing industry. Well, we need to whip up into space now, Colin you're up, because Dave has got in touch to say, if I jump up and down in the aisle of a double decker bus, which is going along, why don't I end up down the back of the bus every time I jump, I just land in the same place.

Colin - It's because you and the bus are traveling at the same speed. So before you jump, let's say the bus is going 30 miles an hour. You are also doing 30 miles an hour. And so when you jump, you both travel down the road at the same rate. Um, if the bus were to accelerate though, then you would end up towards the back of the bus. Newton's first law of motion, right? That something will remain at a constant speed and less acted on by a force.

克里斯- I suppose it's sort of similar to the fact that when you take off in an aircraft and you are flying across the earth's surface, because the atmosphere is moving at the same rate. You're not being left behind by the earth. Because people often say when I take off and the planet's spinning the planet's going a lot faster than the plane is. So why doesn't the plane just take off on hover and wait for the earth to come round to the right place and then land again. And it's the same phenomenon, isn't it? The atmosphere is moving. So you are just jumping into something that's moving and you were moving when you took off. So you just move alongside it.

Colin - Exactly. And so the earth spins at a thousand miles an hour. So if you were to jump, the earth is gonna spin a thousand miles underneath your feet. Why don't you land in a different spot? Where again, because you were really traveling at a thousand miles an hour with the earth when you set off.

克里斯- Here's the kicker then. You must have done that thought experiment when you were little, which is that you're in a lift and it suddenly starts to plummet towards the bottom of the building. I'll wait till it's just about to hit the floor and then I'll jump and then the lift will go smack and I'll be fine. Why won't that work?

Kanta - So I saw a Mythbusters episode about this. About 15 years ago, but they tried exactly this, where they had the lift. They put their dummy in there and tried launching the dummy upwards right before the lift would hit the floor. The only problem was they kept launching the dummy faster and faster and each time it wasn't enough. The dummy would get smashed. And it turns out that in order to offset the force with which the lift hits the ground, you'd have to jump with the same force, but upwards, meaning that you'd have to jump high enough to be able to reach the top of the building from where the lift started. That would just not be humanly possible and also you'd smash your head into the ceiling of the lift.

克里斯- You'd decapitate yourself. You probably wouldn't break your legs, you'd just break your neck instead. So it wouldn't be terribly helpful. Go along with that, Colin.

Colin - Yes, that sounds right.

Lou Ignarro, Nobel Prize winner in Physiology or Medicine in 1998, for discoveries concerning the crucial role played by the chemical nitric oxide in our blood vessels...

Lou - There's a drug called nitroglycerine, which is used to lower the blood pressure to treat pain. When you have an impending heart attack and patients take nitroglycerine, it dilates the blood vessels. That action had been known from the Alfred Nobel dynamite factories back in the 1800's, but the mechanism of action was not known for over 100 years. Being a chemist and a biologist, I looked at the chemical structure of nitroglycerine and thought, "Well, maybe our bodies metabolise nitroglycerine to something like nitric oxide, nitrogen dioxide - or something like that. Maybe that would be the act of principle that causes the vasodilation." So, we did those experiments, and that's exactly what we found - that the active vasodilator ingredient that lowers the blood pressure and increases blood flow in nitroglycerin is a tiny molecule: NO - one atom of nitrogen, one atom of oxygen. After looking at all of these actions, I thought to myself, "My goodness, if this molecule were made in our bodies, it could serve as a tremendous protective molecule against high blood pressure, stroke, heart attack, etc." In a number of different experiments, we were able to show for the first time that mammalian cells, including in human tissue, are able to produce this relatively simple gas called nitric oxide. That was the reason I was awarded the Nobel prize.

克里斯- And how does Viagra come into it?

Lou - Every nerve releases a chemical signalling agent, called a neurotransmitter, that then interacts with the tissue that it innervates to cause an effect. Once we discovered that this neurotransmitter was nitric oxide, then it all made sense; because NO is a vasodilator - it causes vasodilation, and engorgement of the erectile tissue to fill up with blood. That's what the erectile response is all about. The FDA fast tracked the development of this drug and, in 1998, sildenafil, with the trade name of Viagra, was marketed.

克里斯- Going back to how all this began, you mentioned that the bomb industry were playing around with nitroglycerin. Did people who were working in the bomb industry really notice that their heart problems got better?

卢——是的,完全正确。阿尔弗雷德·诺贝尔的前沿空中管制官tory, what was noticed when the people came into work on Monday were two things: first, many of them got a tremendous headache, because vasodilation of the arteries in the head can give you a migraine-like headache. More importantly, however, as working in Sweden was very difficult and there were a lot of diseases (the air was not pure, and many people had angina and impending heart problems), the workers noted that when they went into the factories on Monday morning, the heart and arm pain disappeared, but came back on the weekend when they were home. The physicians in the community recognised this effect and traced it down to nitroglycerin. Within a few years, they were able to get tiny, tiny amounts of nitroglycerin, mix it with sugar - because otherwise it was too explosive by itself - put it in tiny tablets they would then put under their tongue, and relieve the angina. That drug, which is marketed today as Nitrostat, and others were available in the 1870s. But, as I said, the mechanism by which it works was not found until we did it in about 1980.

克里斯- You really are the proper paid up Dr No, aren't you?

Lou - My wife even suggested I should be called 'Dr. No' because she liked the James Bond movie and she was always in love with Sean Connery! Even my license plate on my car in California says DRNO.

Rob - In most people's houses they're just an interesting part of the natural world and, in most cases, the pesticides you would use to kill them are far less benign than the ants themselves.

克里斯- When you mention this whole business about cleaning products, can we actually see the impact?

Rob - I think we're aware of some of the ways we change the habitats around us. We're aware of when the birds change - we no longer hear the same sounds, we're aware of when the plants change - we don't see the same flowers. Hidden in those stories is the fact that we're fundamentally changing how all these pieces of nature work together. Most of the food the animals and cities are eating is actually coming from human waste streams, and if you pick up an ant in New York City, in Manhattan, most of its carbon molecules actually come from corn syrup and from eating animals that have been fed corn. The other thing that we know is that we're triggering totally different evolutionary scenarios: what we now know is that where evolution proceeds most quickly is in habitats that are becoming ever bigger and where the selection pressures are really strong. That's exactly what we've created in cities. And so, there's an underground mosquito in the tube, in London, that appears to be part of a lineage that specialised for tubes and subways. The rats on the South end of Manhattan are diverging from the ones on the North end of Manhattan; the bacteria and other smaller species are evolving even more rapidly - and so they evolve in response to an individual course of antibiotics. I think we look outside and we see something that seems static but, in fact, this evolutionary story is faster than it's been in a long time in many ways.

克里斯- Are the houses that we are making these days a bit too clean for our own good?

Rob - That's for sure. We're coming to understand that we need exposure to certain species to be healthy. Now, which species we need to be exposed to is a very complex question, because it's at the interface of the immune system. But, we do see that as people spend more and more time inside, and their houses are more and more clean, that there are a whole series of broader immune problems that arise: these are skin problems, it's gut problems, it's brain inflammation problems that seem to be associated with these changes. There's been a push now to think about, "Well, what do we need to bring back into our daily lives to restore some kind of a balance?" And it's a tricky question. What the companies want to do is to give you a pill that has the particular microbe we need. What some ecologists want to do is to imagine restoring more biodiversity to our daily worlds, and to get us outside more. It's a tricky time. We know there's a problem, but the solution is not fully apparent yet.

克里斯- No danger of my house being too clean. But, if everyone was like me, what microbes will be taking over first? If we all stopped obsessively cleaning, what would dominate?

罗伯-我先回答相反的问题:international space station is a perfect experiment in what happens if you try to seal everything out and clean really well. In that environment, you mostly get microbes associated with the body because the body's constantly falling apart and so the international space station is full of those microbes. Then you get extreme loving microbes; things that can grow on metal, on plastic. At one point, the windows and mirror of the Russian space station were so covered in fungus that they could no longer see outside, and so the universe was obscured by the grandeur of life. The other extreme is what happens if you open your windows? What happens if you live in a house that has more continuity with the outside world while soil microbes come in, leaf microbes, come in the insects that come in, bring in microbes by and large, those are either benign or beneficial sorts of species.

Colin - As far as we know, traveling through time does also require traveling through space. We know of two ways you can travel into Earth's future and potentially one way you can go backwards, but all of them require traveling through space. It's not a kind of Tardis situation, where you, get in a machine, you close the door and then you open up and you're in exactly the same place. You physically have to move through space in order to move through time.

克里斯- You are saying then that we could travel in time, but we would have to move in the course of doing it. But if we move and something gets in the way in the process, so say you flew across our solar system and you cross the orbit of various planets, you are gonna coincide in space and time, literally as well as metaphorically with those objects. Do you end up just spaghettified?

Colin - Not spaghettified, but any object can be given four coordinates, right? Three space coordinates and one time coordinate. The chair I'm sitting in has three dimensions in space and one in time. If I move the chair tomorrow then it's no longer there. If any two objects share those four coordinates, they're gonna be, they're gonna hit each other. If you happen to go on your big loop around space to achieve your time travel and you crash into mars, then you crash into mars.

克里斯- Of course, there is one other way that we can deform or distort the passage of time. That's by either going very fast or going near things which are very massive. Both effects actually are happening very visibly on earth right now, because if we didn't take into account the fact that Earth's gravity distorts time, our GPS system wouldn't work.

Colin - They're the two ways of traveling into the future that are kind of alluded to. You've got two options like you say, go fast and return to the earth and you'll realise that more time has passed on the Earth than you think, so you just skipped ahead into the future. But again, that requires you to move through space. Or you go and hang out near something really massive, like a black hole, and then return to the Earth and you have the same effect, but that still requires you to leave the earth and come back. The GPS satellites, that's the best piece of evidence I can give that time travel is real. Every time you push that button on your maps app on your phone, that brings up that blue dot, you are using the physics of time travel. As you say, the system works because your phone receives a signal from the satellites in the GPS, but to do that, you need three or four satellites. It works out how long it's taken to arrive at your phone. The quicker you arrive, the nearer you are to that particular satellite. But to do that, the satellites have to have to timestamp the signal so you know how long it's taken. They have atomic clocks onboard that keep track of time, but time is running at a different rate for them. As you said, for two reasons, one they're traveling at speed. Then two they're slightly further outside Earth's gravitational field than we are down here. So, we have to artificially change the time onboard those clocks to hold them back into our time. If we didn't do that, the blue dot on your phone would be out by 10 kilometers in one day. So, people don't always buy into time dilation, when they hear it for the first time, they say this is just a gimmick, it can't be real, but you rely on it every time you push that button on your phone.

AI is having more and more influence on the way the world operates each year, conveniencing our day to day lives in ways we could never have imagined. It can also be used, however, to encourage our behaviour for the benefit of companies after our cash. Kanta Dihal lifts the veil for Chris Smith, on how supermarkets are attempting to alter our shopping habits using patterns identified by artificial intelligence...

Kanta——我想知道有多少人知道,前女友ample, of the ways in which AI related software and algorithms work in supermarkets. My favourite example in this comes from Hannah Fry and her book on algorithms. TESCO, which for my American fellow panelists is one of the biggest supermarkets in the UK, has been collecting data on what people buy in the supermarket for decades and has been using that information to identify trends. For example, people who buy 'xyz' are also more likely to buy 'abc'. Therefore if you put one on offer, but raise the price of the other one then you might end up selling more and making more of a profit. Or maybe we should put one specific product closer to another product on the shelves, because people always buy them together. My favourite example, which Hannah Fry described, was when they started combining this with offering mortgages and loans. They discovered that people who buy fresh fennel are more likely not to default on their loans.

克里斯- Does she offer any kind of reasoning why or is it just that very middle class people who are probably better off buying fennel and they've probably got a bigger bank balance?

Kanta - That's probably a very large part of it. There's lots of things coming together here about people being middle class and being traditionally middle class, having grown up knowing what fennel is and how you use it along with having enough time to cook it and enough money to purchase it. Lots of assumptions about class background and ethnicity come together here that influence those correlations. These are kinds of discoveries that these algorithms make that can reveal biases or assumptions that we didn't even have, or that we didn't know we had, but that become extremely stark when you just run the numbers on them.

克里斯- We know that E = mc², Einstein's famous equation where energy and mass are interchangeable. Can the same be said for dark matter and dark energy?

Colin - No. You're right to say that normal mass and energy are two sides of the same coin; You can convert one into the other. Whereas dark matter and dark energy appeared to be polar opposites; they're doing very different things. Dark matter is like a glue that helps stick things in the universe together, like a galaxy, for example. Whereas dark energy seems to be something that's doing the opposite. Not binding things together, but pushing things apart. Around the same time that Viagra came out, we discovered that the acceleration of the universe is accelerating. There's something between galaxies that seems to be pushing it apart. We call these things respectively dark matter and dark energy, but really they're placeholders for our ignorance. We don't know what either of those two things are. We just see the effects they seem to be having on the universe.

克里斯- Yes, indeed. I did actually meet the guys that weighed the universe and worked out that things were not just getting bigger, but getting bigger, faster. We still don't know the mystery behind that. Did we? Because as space makes more space and distances become greater. It's almost as though it makes more dark energy. It's something of an enigma, isn't it?

Colin - This is another key difference between dark matter and dark energy. The majority verdict is that dark matter is a physical thing, it's a substance that exists in space. Whereas the dark energy seems to be a property of space itself. As space stretches, it becomes more and more dominant. It's another reason why the dark matter and dark energy seem to be different things. The only thing they have in common is that 'dark' word, and that's basically our ignorance.

克里斯- One cynic said to me, that 'dark' is the word that physicists put in front of things to make them sound sexiest. So you get more grant money, but I'm sure that's not true.

Colin - The person who came up with the phrase 'dark matter', was Fritz Zwicky back in the 1930s. Knowing how eccentric he was, I can't imagine he was doing that. But dark energy? Yeah. Maybe they just thought 'good sounding thing'.