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

We're answering your questions on motion, cleanliness and the Disney robot WALL-E?...
24 February 2022
Presented by Chris Smith
Production by Harrison Lewis.


An image of a woman with cybernetic components beneath her skin


It's that time again, where we compile all those lovely science questions you have sent in and form a crack squad of expertise, throw them on a panel together, and shove a mic under their noses! This week, you'll meet a Nobel laureate, figure out if the word 'dark' is put in front of complex theoretical physics topics to make them more attractive, and come face to face with our greatest bodily enigma: your armpit! Plus, with it being women in history month, we'll put your memory to the test to see how well you really know your great ladies of science...

In this episode

Artificial intelligence (AI)

06:42 - Defining intelligence

Are artificial intelligence machines actually intelligent?...

Defining intelligence
Kanta Dihal, University of Cambridge

Before we can understand how a robot can think (and maybe feel) in the same way a person can, we should start by getting a better understanding of what’s going on inside our own heads. Kanta Dihal and Chris Smith discuss how we definie intelligence? 

Kanta - That's a great question to start with and it's a surprisingly difficult one. Because there was one study recently, which identified more than 70 different ways in which intelligence has been defined over the years, which is of course extremely unhelpful if you're trying to artificially reproduce it, if you're trying to build it, if you don't actually agree on what intelligence is. And so, all kinds of tests were invented, they also very strongly depend on your culture, on how you grew up, what kind of resources, what wealth you grew up with. Now, trying to translate that to artificial intelligence gets really difficult because, artificial intelligence aims to reproduce something, well, hopefully that is more like how a human in general or on average thinks and functions.

Chris - Is that what we want though? Because to my mind, you know, humans are pretty good at being humans. And I mean, some people obviously take the biscuit a bit, but on the whole, we're pretty good at doing what we do, but we've got flaws, we've got weaknesses and that's where machines can help us rather than invent something that's basically more of us. Do we want more of the same? Or do we want something that's not gonna be encumbered by the biases, by the difficulties, the intellectual constraints that humans seem to struggle with?

Kanta - That's a great point. Yes. In many ways people are trying to develop technologies that are better than humans in some respects, but there is also for some researchers this end goal of at least being able to reproduce human intelligence and create something that is at least as good as humans being able to do the same kinds of things that the human brain can do.

Chris - Did you wanna come in there Lou?

Lou - Just I'm fascinated with this.

Chris - Do you think that an artificial intelligence would invent Viagra?

Lou - I think that given the right information yes. But you know what Kanta is saying I think it's absolutely right. You need to start off first with trying to mimic what humans do instead of right away, trying to make you know, the artificial intelligence better to have a, you know, the robot or whatever think better, think more outside the box. You've gotta be able to duplicate what we do. But I think after that you can then take a step further. And I think, yes, if the robot I'm calling it that I don't know what else to call it has all the facts built in has a good knowledge base then, you know, knowing what I knew, what I discovered, I think that artificial intelligence could have come up with the answer and maybe even a better answer, and maybe even a better chemical drug and do it faster.

Chris - That is happening. Isn't it? I mean, pharmaceutical companies are investing very, very hard in computer systems that can explore chemical space and find molecules that look like they would be fit for doing a good job. I wonder

Lou - It's a lot cheaper than random screening of a thousand different chemicals.

Chris - Absolutely.

Lou - Because there's no intelligence behind that. So with artificial intelligence, we can get right at the heart of the matter, so to speak.

Rapid changes in the genes for transfer RNA have been observed have been observed in experiments on yeast.

From fungi to beer: the evolution of yeast
Rob Dunn, NC State University

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.

Chris - 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".

Chris - 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

Chris - 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.

Chris - 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.

Chris - 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. 

Chris - 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.

Chris - 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.

Isaac Newton

Newton’s first law of motion

Blood vessel

17:08 - Nobel Prize Winner: Dr NO

Nitric oxide has been found to be crucial to bodily functions, but how does it work?...

Nobel Prize Winner: Dr NO
Lou Ignarro, UCLA

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.

Chris - 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.

Chris - 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?

Lou - Yes, absolutely right. In Alfred Nobel's factory, 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.

Chris - 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.


Hollywood’s AI obsession
Kanta Dihal, University of Cambridge

Artificial Intelligence is a feature of so much popular media and science fiction. From 2001: A Space Odyssey to Westworld, Bladerunner to The Matrix. Chris Smith and Kanta Dihal figure out which Hollywood blockbuster is close to getting it all right...

Kanta - There have always been, in mythology, stories about people building thinking machines or intelligent objects that get out of hand because they didn't get the right instructions or they took their commands too literally, or they were too strong and uncontrollable. Any reason that you could come up with where an intelligent machine could cause havoc has already been conceived 1500 years ago.

Chris - But the people making these suggestions are not nut cases necessarily, are they? Stephen Hawking said some pretty strong things about these sorts of technologies, and said that they would be the death of us.

Kanta - So, on the one hand, you have these stories of super intelligent machines that might not think humans are worth hanging out with because of our track record, and on the other hand, there are the limitations to the kinds of things that we have been building so far. The massive flaws some of these technologies have turned out to have, but still the huge trust that is placed in them, and the extent to which human common sense is sometimes being replaced by them.

Rob - Kanta, I was wondering if there was any speculative fiction, or even any movies, that you think does a good job of capturing the AI scenarios that you think are most likely?

Kanta - That's a really interesting one. One scenario that is obviously extrapolated into the ridiculous, but I still think is worth thinking about is depicted in WALL-E, which touches on two really interesting things. One is the idea of over pollution, of humans having destroyed earth, and then trying to fix it using technology - you have the little robot WALL-E trying by his little self to tidy up these massive landscapes of waste that humans have created, and I think that is a very important message when thinking through technological fixes to things that we have done in the past. The other one is how dependent the humans depicted in the film are on technology, because they're all these blobs who never come out of their chair and always sit in front of the screen.

Chris - Quite accurate in that respect then.

Kanta - And this was before the invention of the smartphone. So yes, absolutely.

Bed bug: Cimex lectularius

24:43 - Beneficial bugs and the drawbacks of cleanliness

As much as you try and clean your house, the pests are always going to come back...

Beneficial bugs and the drawbacks of cleanliness

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.

Chris - 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.

Chris - 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.

Chris - 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?

Rob - I'll answer the opposite question first: the 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.

Astronaut and physiologist Jessica Meir

March Quiz: Women in History Month
Kanta Dihal, University of Cambridge, & Lou Ignarro, UCLA, & Rob Dunn, NC State University & Colin Stuart

It’s that time where we take our wonderful panelists and pit them against each other in a battle of wits, competing for a prize beyond price: the Naked Scientists big brain of the week award. The month of March marks women in history month, so that’s our theme…

Chris - Our teams are Kanta and Rob team one, Colin and Lou team two. You are allowed to confer, but you mustn't try to put off the opposition. There's no naughty tactics allowed here. Question one, this is for team one, Kanta and Rob, as of November 2021 to the nearest 10, how many female astronauts have undertaken space flight? Is it A) 250 B) 100 or C) 50? What do you think?

Kanta - Hmm. I'm guessing it's not more than 50. Probably.

Rob - Yeah, I would agree on that.

Chris - Going 50?

Rob - Yep.

Chris - Quite right. There've been 502 men and 50 women. So far the longest space flight yet was a whopping nine hours. Now that accolade does go to women, that was pioneered by Susan Helms in 2001, I could say Hemed by Susan Helms in 2001. Wow. Also another claim to fame, Naked Scientist, contributor, Jessica Mayer ended up walking in space. A lot of big names appear here on The Naked Scientist. Okay. Over to you, question two for team two, one of the unsung heroes of paleontology is Mary Anning. In 1811, she found a fossil unlike any other that had been seen before in Lyme Regis, it was 5.2 meters long, but what was it? A) Pterodactyl B) Megalodon or C) Ichthyosaur? What do you reckon Colin and Lou?

Colin - Pretty sure it's C. I've been down to the Jurassic coast before and yeah I think it is an Ichthyosaur.

Chris - Solid, confident answer, and you're absolutely right. It is an Ichthyosaur. That word means fish-lizard. These were the reptile inhabitants of the seas Pterosaurs glided in the air, dinosaurs walking on the land all around at the same. Ichthyosaurs looked a bit like modern day dolphins, except they had absolutely massive teeth. The smallest one was about one meter long, the biggest one, a Shinosaurous, wonderful name, 23 meters in length. But loyal listeners to the program will remember us reporting just last month discussing the largest Ichthyosaur that's now been found in Britain. It was over 10 meters long. A fearsome beast, right? We're level pegging, both teams on a point a piece, onto round two. This is on Nobel prizes. One of our team members might have an advantage here. Question one. This is for team one Kanta and Rob. Four women have won Nobel prizes in physics since 1901, Andrea Ghez the latest female to be awarded the prize. She got that in 2020, but what did she discover? Was it A) the black hole at the center of the Milky way B) the creation of a chirped pulse amplification also known as a CPA Or C) did she discover the mass of a neutrino? What do you think?

Rob - I'm just gonna be guessing Kanta, any ideas?

Kanta - I think it was black hole that she did.

Chris - Are you going black hole? Yes. Andrea Ghez received the 2020 Nobel prize in physics, alongside Roger Penrose and Reinhard Genzel for their work on black holes. Her work and Genzel's work provided the most solid evidence yet for the existence of a super massive black hole, we call it Sagittarius A*. It's ironic. You put a star on a black hole name, but that's at the center of the Milky way galaxy. Another point, over to team two who are Colin and Lou Marie Curie won the Nobel prize for the discovery of the highly radioactive elements, radium and polonium, but which of these would give you the biggest dose of radiation? A) living in Cornwall B) a chest x-ray or C) a bag of brazil nuts?

Colin - There's quite a lot of mining down in Cornwall. There's a lot of stuff down there that could provide a dose of radiation. You'd think it probably wouldn't be the chest x-ray right? So, it's either the Brazil nuts or Cornwall, what do you reckon?

Lou - Brazil nuts have a lot of selenium, but I don't know what that has to do with radioactivity. I would have to go with the first answer.

Chris - Quite right. Living in Cornwall is the biggest risk factor on that list, but they're not all nuts, if you excuse the pun. The average UK citizen gets about 2.7 millisieverts, which is a measure of radiation, per year just from natural sources. A chest x-ray and a bag of brazil nuts actually give you about the same dose of radiation. It's about 0.01 millisieverts. But here's the kicker. If you live in Cornwall, your dose annually is about 6.9 millisieverts. So, nearly three times your background exposure across the UK. That puts you on par with having an annual chest CT scan, which is a very big dose of radiation. Back to team one who are Kanta and Rob for round three, question one, Sylvia Earle was a pioneer of ocean exploration and she was the first hero of the planet to be named by Time magazine. She accrued over 6,000 hours underwater, but which of these is the only true fact about scuba diving after 10 meters down? A) You can't see yellow or red B) nitrogen narcosis otherwise known as the bends kicks in at 10 meters underwater or C) the buoyancy of air in a scuba tank means that divers need a weight belt to hold them down underwater? Which is the true answer from those three?

Kanta - As a scuba diver, I know that nitrogen narcosis doesn't necessarily kick in at 10 meters. It's not guaranteed. It's not the air in the tank, but mostly the air in your lungs and suit that creates the buoy.

Rob - So, what does that leave us with the first one?

Kanta - 10 meters seems very early to stop seeing colors.

Chris - You're gonna have to pick one.

Rob - Let's go with the nitrogen narcosis one.

Chris - The answer is actually A) you can't see yellows and reds properly. Once you get more than 10 meters underwater, you'll appear to be bleeding a black color. The reason for this is that water strongly absorbs light at the red end of the spectrum. The bond between water molecules is strongly attenuating red wavelengths. As you go further underwater, you remove more and more red light from the light that's coming through the water. This means there's virtually no red light left to bounce back at your eye from the red in your blood, making anything that's that color look black. Nitrogen narcosis does kick in from about 20 meters. You're sort of right there, as soon as you go underwater you're beginning to dissolve more nitrogen in your bloodstream, but most people are all right until they get to at least 20 meters. Good physics on the last question, you're quite right, the air in the scuba tank is very heavily compressed, which means it actually weighs more than the water that the tank is pushing out of the way. It's actually negatively buoyant.

Lou - Really good science

Chris - Team two you may, Colin and Lou, have a chance to clinch this one. Jane Goodall is best known for her time spent studying chimpanzee families, but what name other than troop do we give to a group of baboons? Is it A) a flange B) a sleuth or C) a coalition?

Colin - Lou there's a famous Rowan Atkinson sketch where he called them a flange of baboons. I think they actually adopted the name flange from the Rowan Atkinson sketch.

Lou -Then let's go for it.

Chris - You're absolutely right. I love the logic that Rowan Atkinson educates the world in science. Very good. It's a flange of baboons. It is a sleuth of bears and a coalition of cheetahs.

Lou - Cheetah.

Chris - I think it should be a deception of cheetahs myself, but then that's just me! That means you guys got three out of three and The Naked Scientists Big Brain of the Week award goes to team two, very well done. Let's give them a round of applause.

Lou - It was mainly Colin. Thank you.

Stylised depiction of the fabric of spacetime.

38:47 - Time travel

Spacetime conundrums give Hollywood a run for their money...

Time travel

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.

Chris - 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.

Chris - 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.

An image showing the arteries and veins in the lungs.

42:51 - NO nasal spray?

Could it be a potential cure for Covid?

NO nasal spray?
Louis Ignarro

Nitric Oxide (NO) relaxes the innter muscles of the blood vessels, allowing them to widen and circulate blood around the body. It is produced naturally by most, with those who struggle to produce enough NO suffering from a condition called pulmonary hypertension. Getting NO into your body can be tricky given its reaction with oxygen in the air, and so scientists have had to get creative to try and solve this particular problem. Lou Ignarro tells Chris Smith all about it...

Lou - I'm not sure exactly how much more can be told until these experiments and trials are really completed. Let me start by explaining really that NO or nitric oxide is a very unstable gas. In the presence of the oxygen in the air, the half-life of nitric oxide is about 1 second. You cannot put nitric oxide gas into a nasal spray and deliver nitric oxide. It would be delivered as nitrogen dioxide, which is not too healthy for you. Now, there are a number of small companies trying to develop chemicals like nitrites and nitrates. The same sorts of molecules found in green, leafy vegetables and beets and beet juice, and so on. If you put that in a nasal spray and you spray it, then the nitrite and the nitrate can somewhat be converted to nitric oxide, which you can then inhale. But to the best of my knowledge, this is not an effective way to deliver pure NO into your lungs, the only way we know how to do that is to inhale nitric oxide. That's where the idea of the nasal spray came. For 20 years in the clinic, there are gadgets that can produce nitric oxide as needed, mix it with the air and the patients breathe it in, and it works. The nitric oxide gas gets into the lungs and this has been used to treat infants and new-borns with persistent pulmonary hypertension and save their lives. Also, this kind of inhaled nitric oxide has been successful in treating COVID.

Chris - There have been a lot of observations that people who have heart disease and high blood pressure tend to come off worse. Do you think that your molecule, nitric oxide, is bound up in that observation and the fact that people are trying this as one way to minimise the impact of COVID is linked as well?

Lou - Yes, there's no question about it. First of all, in COVID the problem is that the coronavirus or the strains of it, all must get into the lungs. They attach to the alveoli where there's oxygen exchange and blood flow and these viruses destroy the inner linings of the arteries. It's called the endothelium lining and those are the cells that make nitric oxide. We make nitric oxide everywhere, but in our lungs we make it for several reasons. To dilate the arteries, so that more blood flows through the lungs and can therefore pick up more oxygen. Nitric oxide is also a fantastic antiviral agent. Nitric oxide will destroy many different viruses, especially the coronavirus, in the lungs and prevent their spread. Also nitric oxide deficiency is associated with all kinds of cardiovascular diseases, coronary artery disease, or atherosclerosis in other parts of the body, and so on. If you decrease it further, you're going to have problems. Patients with covid who have some cardiovascular problems, their cardiovascular problems are going to get a lot worse.

A supermarket aisle empty of people.

46:47 - Robo-shop

How AI is trying to influence consumer behaviour in supermarkets...

Kanta Dihal, University of Cambridge

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 - I wonder how many people are aware, for example, 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.

Chris - 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.

Female Armpit

49:15 - Pit's a Wonderful Life

Why our natural human body odour is not something to be ashamed of...

Pit's a Wonderful Life
Rob Dunn, North Carolina State University

It sounds like something out of a science fiction horror, but we humans have all sorts of microorganisms living on our skin and inside our bodies. In our armpits, microbes metabolise the food we give them, producing a distinctive smell. But one man's B.O. is another's bonding mechanism, as Rob Dunn explains to Chris Smith... 

Rob - We're really a collective. All of our attributes of our bodies that we think of as the function of our own cells really are more often collaborations and antagonisms between our cells and the microbes on our skin, the microbes in our guts, the mites that live on our faces and all over our bodies. This is inconspicuous when we look at each other with our eyes, but if you close your eyes and you sniff people, almost all the smells of humans are microbial. To the extent that you love the smell of your partner or you hate the smell of your partner, I hope you don't hate the smell of your partner, but if you do, it's really a very direct manifestation of this cooperative between our cells and these microbial cells.

Chris - I interviewed a researcher for the journal eLife a few years ago when he published this paper. When I first read it, I thought it couldn't be real. He did a study where they had cameras set up to watch two people meeting each other. One was in on it and other people just thought they were coming to be interviewed about something random. They had rigged these people up with a system to measure when they sniffed. Some of the time the interviewer that they were meeting shook their hands and other times they purposefully didn't shake their hands. The hand that had been shaken spent significantly longer in front of the person's face coinciding with sniffing than other times in the interview. He said it was really funny because he presented this at a conference and he said, he then went to the party in the evening where it was a meet and greet or 'get to know each other' time welcome drinks. He said everyone was walking around with their hands in their pockets because no one wanted to shake hands.

Rob - I mean this relates to what I think is like one of the biggest mysteries of the Earth. It's on par with the pyramids in Egypt, which is the human armpit. We have these glands in the human armpit called apocrine glands and the only thing they do, and this is very clear is they feed particular microbes. When they feed those microbes, they metabolise the food that our bodies give them. That's what armpit odour comes from. In non-human primates we know that aroma is super important for signaling between individual. Gorillas can tell each other apart by sniffing. It's this whole organ that was very key evolutionarily and that we've now tried to hide in any way that we can.

Chris - That's exactly what was on the tip of my tongue as you were saying that. Why have we evolved then to try and hide it? Why do we go to enormous efforts to mask this stuff? Is that just learned behaviour?

Rob - A big part of it is the pharmaceutical industry, the cream and antiperspirant industry, which sold us on the idea that we need those products. A big part of the globe has a version of these apocrine glands that are sealed shut, it's a single gene difference. This is true in most of China, but the antiperspirant companies have found that they can sell antiperspirant to those people just by convincing them that they might smell. But also I think our armpits betray our emotional status, they betray our health. You might imagine that there's some advantage socially to hiding what's being said there.

Dark Energy

52:48 - Dark Matter vs Dark Energy

What is the relationship between these ominous sounding entities...

Dark Matter vs Dark Energy

Chris - 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.

Chris - 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.

Chris - 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'.

A Nobel Prize medal on a black background.

55:14 - How to become a Nobel laureate

And how excellence can be achieved by those with humble origins...

How to become a Nobel laureate
Louis Ignarro

Lou Ignarro recounts his immigrant family's settling in America, and his own interest in science from a young age. He attributes a fascination with chemistry and biology in his formative years, combined with his incessant questioning nature, as crucially significant to the later success he enjoyed in his field...

Lou - I can only tell you about myself. For me it was a really incredible roller coaster ride. My parents were immigrants from Italy. They moved to New York where they met, they got married and I came along. My parents never went to school, they were completely uneducated. That trickled down on me, because when I started elementary school I didn't know that much. My English was very poor. My Italian was good. Nevertheless, because of my passion and motivation to learn, I was able to continue and raise my grades through elementary school. I had a great passion for science. Why did I love chemistry? I liked making firecrackers. I liked making bombs, which I made quite a few of. I loved biology. I liked dissecting animals I found outside and noticed how their organs resembled the human organs, which I used to look at from an anatomy book. I never lost my passion and interest for science and I kept raising all kinds of questions. The one question I raised in high school, for example, was 'how come so many of my friends and relatives die of cardiovascular disease when they're 50 and others just live on and on and on and never get sick?' I thought that ‘maybe healthy people produce some molecule in the body that protects them against heart disease and the ones who get sick are not as lucky and they don't make enough or any at all.’ Well, I kept it in my mind as I was going through my studies. One thing led to another. We did some experiments and we were able to find that molecule; nitric oxide. But to get to that point, I had to struggle. I remember a quote from Ralph Waldo Emerson who said "Do not go where the path may lead, but instead, go where there is no path and create a trail."


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