How Old is the Average Atom?

We put this question to physicist Caroline Steel...

Caroline - Firstly, the sun is 150 million kilometres away. So actually, climbing up a mountain or sort of moving a little bit further away from sea level is really quite negligible in comparison - there's 150 million kilometres. So that in itself shouldn't really have an effect on temperature. But it does get colder as we increase in altitude. There's lots of ways to look at this but one way to think about it is, as air rises, it feels less pressure the higher up it rises. So it expands. And to expand, the gas must do work and to do work, it must lose energy, and therefore, the individual gas particles have slightly less energy. And the definition of temperature is sort of the average energy of these molecules. So, if the molecules have less energy at a higher altitude, there's a lower temperature.

Kat - So basically, temperature, something that's hot, it's all the molecules that are squished together and then moving a lot and that's really hot. And then if you're going up into space, the air just kind of goes wooh!

Caroline - Yeah, exactly. It spreads out and by spreading out, you have less molecules with less energy and therefore, lower temperature.

Kat - David?

David - Yeah. What Caroline is describing is for lower atmospheres. This is probably what the questioner is asking about. But you get above the troposphere into the stratosphere, it starts to get warmer again because that's where ozone molecules are absorbing solar ultraviolet energy so it does get warmer. But there's another layer beyond that called the thermosphere where the temperature is officially thousands of degrees, but you wouldn't feel hot if you were there because it's almost a vacuum. It's just the energy of the individual molecules. It's absorption of solar photons that shake at the molecules.

Kat - Ah, so they're really going as we're up there.

David - They're going for it but they are so few and far between. There's high temperature but almost no heat.

Kat - And then when you get out of the atmosphere then you're really in trouble.

Caroline - So what would you sort of feel if there's a thermometer there? Would it have a high temperature or a low one, or does it sort of depend where it is - is it near the molecules or not?

David - What a thermometer is filled with mercury or something? I don't know. It depends how you define temperature. The molecular temperature is hot, but you would feel cold. You would need to be wrapped really, really warm apart from being almost in a vacuum.

Adam Townsend put the wind up this one...

Adam - Yeah. I thought this was an absolutely terrific question. The Earth slows down because of its gravitational interactions with the moon. So, every time the moon goes around, it affects the tides, robs the Earth a little bit of some rotation. I can tell you exactly how much it's slowing down. In fact, we lose about 2 milliseconds from the day every 100 years. Kat - Yeah. I suppose over millions of years, that's going to add up.

Adam - In fact, it does. So, if you are interested when we're going to get 25-hour days? 200 million years, so not long. Anyway, to wind, wind is caused by warm. so the air on Earth gets heated up by the sun, rises and this causes a pressure difference because the hot air has gone up and so, cold air needs to be sucked and it's sucked in from the north pole or the south pole where it's colder. So, you end up with a circulation happening. But it's complicated because the Earth is spinning. So this is the famous coriolis force. If you sit on a spinning chair and you spin yourself around, and you throw like a tennis ball in front of you, the tennis ball seem to sort of veer off to the right from your perspective. And so, this confuses things because it means that the wind isn't directly going from the north pole or south pole to the equator. And, what I think is the absolute most interesting, despite the fact that we have these areas of high pressure and low pressure, and you would think therefore the wind goes from the high pressure to the low pressure, it doesn't. Actually, because of the rotation of the Earth, wind travels along lines of constant pressure. This is why we have isobars on newspaper weather reports.

Kat - The little lines when you see it, yeah.

Adam - Yeah, like from the '90s.

Kat - They are being replaced by little arrows now because we're too stupid to understand isobars.

Adam - Right. but yeah, it turns out, wind goes along these and this sort of drops out of the maths of the coriolis force. Anyway, "Was it windier in the past?" is the question. The answer is, it's complicated because lots of things affect it. So, continents slow down wind. If we're standing right here and you want to go back millions of years, well obviously, you have the buildings that are going to make some effect. How much land there is around us? Wind could go slower over land because of friction. So it slows down because.

Kat - So basically, there's lots and lots of things that could've made a difference and we don't really know. We don't know if the dinosaurs were like blown around.

Adam - So in the question they asked, if you spin a planet faster, you increase the wind speed. I'm not convinced. I think there are lots of things that affect wind speed. The effect might in fact go the opposite direction. You can get planets that go around very, very slowly like Venus. Venus has a day of 116 days. It's really slow.

Kat - I don't want to go to Venus and find out if it's windy out there.

Adam - 200 miles an hour, who knew?

Kat asked David Rothery to answer this, slightly depressing, question...

David - Paul is saying the magnetic core of the Earth is cooling down. I think what he's getting at is when the outer part of the core is fluid and electrically conducting. That's where the Earth's magnetic field is generated and if a planet no longer has a magnetic field it is not protected from the solar wind and the atmosphere can begin to be stripped away. So, if that were to happen, it would be an uncomfortable place for us to live but Mars has no magnetic field and we will still regard it as habitable for microbes. So, even if this happened to Earth, it would not end life on Earth Paul. So, if you're a microbe, you can relax. The core is cooling down, it's about 100 degrees per billion years. It's got a way to go. It's got several billion years before it would solidify. I can't tell you how long because we're not quite sure what it's made of so we don't know what temperature it will solidify at. But the sun is going to swell up into a red giant in 4, 5, 6 billion years and that's going to make the Earth intolerably hot for any kind of life. No more liquid water. So to answer the question, for any kind of life at all, the sun becoming a red giant is going to kill off life. If the question is about multicellular animal life at the Earth's surface, maybe magnetic field collapse will do that first, but we don't actually know.

Kat - Andrew.

Andrew - I've heard that the magnetic poles can reverse as well earlier.

Kat - Yeah, I was going to ask about that. It comes up in the news, like if the poles flip, our atmosphere will fly away and we'll all be stuffed?

David - No. The Earth's magnetic field is reversed many times. It gets weaker and then builds up again in the opposite direction. It happens every few hundred thousand years at irregular intervals. So it happened so many times and life is just carried on through. No signs of mass extinction events every time the poles flip.

Kat - I wonder about, what about things like our communications network and stuff like that? Is that going to cause a problem?

David - Well, they will cause a problem because yeah, satellites in space.

Kat - No Pokémon, no civilised life.

David - .won't be protected from the solar wind directly. Technological life could be very interesting in the few hundred years when the field is collapsing and rebuilding, yes.

Kat Arney gave us her expertise on this one...

Kat - That is a great question. You have to be very careful because there is a word for trying to engineer the human gene pool. It's called eugenics and it doesn't really ends terribly happily. I've been talking to some people about this and they say, well, you could argue, yes, it's bad for human evolution if you're keeping these things in. but at the same time, you're keeping a whole load of other stuff in as well that might be useful." So, as we have to adapt and change to the changing conditions and the changing world we're living in, there might also be some good stuff in there as well. So, it's very difficult to look at one gene or one disease and say that's not good for our gene pool. But what's really interesting is that it used to be, when you'd look at families with genetically caused diseases, things like - breast cancer is a good example, if people have the Angelina Jolie genes, BRCA 1 and BRCA 2. You could track families with the disease and look at people with the disease and go, "Okay, you've got that gene fault. That's what caused it." but now, we're starting to look at healthy people because genome sequencing is so cheap now and finding that they have "bad" gene variation or gene faults, but they're healthy. They're fine. People tend to call them genetic superheroes. It's absolutely fascinating trying to work out so what else is it in their genome that is causing them not to be ill? So again, it's like when we're thinking about kind of screening out or getting rid of these genetic diseases that we may be losing other things from people that actually have these variations but are healthy. Andrew.

Andrew - And also, for some diseases, it's entirely futile because they're spontaneous mutations anyway. So they may be genetic once it appears in the population but things like Huntington's will appear even if you haven't got a parent with it sometimes. So, you can't entirely remove them anyway.

We put this question to biologist Andrew...

Andrew - Well, if we just move back from the question and think about what the intestines have to do. So intestines have to get all the stuff out that grass partially digested into the body but only the bits we want. So they mustn't get out all the bacteria which could be toxic. You don't want to get it into your bloodstream and get septicaemia. You don't want to get any toxins that are on the food. So, your gut really is a very, very clever system that only transport and get what it wants. So, some of that is done by osmosis. So the concentration of different molecules draws the water out and some of it is done actively. So energy tends to pour food out. Of course, you then have the blood system actually, not a tiny gap before you ended up with the other while you make the milk. Of course, the cells there are very carefully putting the right things in that milk, not just anything they come across. So, if you didn't have a good barrier with your intestines, you would be getting really sick over time. So it wouldn't just be going in milk. It would be going everywhere. Actually, if we think about the milk, for the one thing you probably don't think about is you do get infections in others or in people in breasts and you get mastitis. This is a real problem for people with breastfeeding because you got this milk which is very good for growing bacteria. You get this really sore infections and it's really unpleasant for the mother. Of course, the solution today is just antibiotics but you do have to make sure you don't get bacteria in there because they have these horrible side effects.

Kat - And also, there are some bacteria in milk and that's presumably why we pasteurise it so that we don't get sick from drinking it.

Andrew - Yeah. But they can come in different stage. They can come in through the pumps and stuff like that. What you give to a baby also come from many of the immunities from the mother as well. So, it's a complicated product, milk.

We put this question to the team...

Andrew - So this is absolutely brilliant. You've got to first start how do you get in space. With a lack of a transporter there, I'm going for someone who opens the airlock whilst you're taking a nap and it's on the ISS and suddenly the pressure drops. The first thing that's going to happen, it's a bit cold because we've got the gas expanding again - we discussed earlier. You're going to also notice that the air is going which you need to breathe. So the crucial thing to do at this point is you got to remember not to hold your breath.

Kat - That's really hard.

Andrew - I don't think so because if you just think you need to scream, that might be quite natural.

Kat - Okay.

Andrew - Because otherwise, all the air in your chest is going to want to expand through your chest and that's not going to be good for you.

Kat - Okay, so you would explode from your lungs. Caroline.

Caroline - You'd also have to be careful to not cry. Because of the lack of gravity, your tears don't fall. They just kind of accumulate on your face and can block your mouth and nose, and you could drown in your own tears.

Kat - Will they be frozen though?

Caroline - I suppose. Would they freeze?

Kat - You drown in your own frozen tears.

Andrew - Oddly, they boil and freeze. So the low pressure means they boil, but the low temperatures mean they freeze. So you get this kind of micro crystals forming.

Kat - Abrasive or sort of maybe exfoliating.

Andrew - Well, they're probably going away from you.

Kat - Adam, what do you reckon?

Adam - Well, I was going to ask, how much time are we giving ourselves here?

Andrew - Well, not very long which is very - the door has opened, the air is rushing out. It's like a balloon.

Adam - Are we talking we have maybe a minute to live or.?

Andrew - So on the air front in 15 seconds, your brain will basically decide to protect itself and you'll be unconscious. In about 2 minutes, you'll be asphyxiated.

Adam - So, we're not worrying about the abrasive effects on our skin of our frozen tears then because we're going to die because it's hard to breath.

Andrew - If someone gets to you in 2 minutes and if you're outside the ship by this point, you're going to start to get sunburn quite badly. As you got high factor sun scream you';ve avoided this.

Kat - Why would you get sunburn in space? You always think of it as being like dark and cold. Why would you get sunburn?

Andrew - So on the Earth, we have the ozone layer protecting us from all the UV but you take the ozone layer when all these things protect us on the planet, and suddenly, you've got raw sunlight on top of you. So, you're suddenly going to get a huge amount of radiation on your skin. Kat - This always reminds me of the joke about the astronauts who wanted to go to the sun and then thought, "Well, it's going to be really hot during the day so let's make sure we go at night."

We put this question to planetary scientist David Rothery...

David - Well, I admit to having had to look this one up. It depends whether Donald is talking about the solid Earth or the planet Earth including its atmosphere.

Kat - What are the differences then?

David - The ground beneath your feet does carry a negative charge. The atmosphere carries a positive charge.

Kat - So does that help to keep the atmosphere on?

David - No, that's gravity.

Kat - Right, it's gravity so it's not related.

David - It does explain why there are lightning discharges sometimes between the atmosphere and the ground. That's just a current pathway forming that lets the charge neutralise locally. Now, why do we have this charge imbalance? It's very hard to understand and it's defeating me but the positive charge on the atmosphere would be because the Earth is receiving charged particles from the sun all the time. Protons newly formed hydrogen nuclei, to go back to the previous question if you like, streaming along magnetic field lines towards the Earth. Some negative particles mostly electrons steaming along as well. So the charged particles going past the Earth are deflected by a magnetic field. But some particles, some electrons and our atmospheric atoms especially our outer atmosphere are stripped away in this solar wind. I think that's why we get a positive charge in the atmosphere because we've lost a few electrons. I guess lightning discharges between the atmosphere and the ground locally redress that balance every so often. But it's very, very complicated. Because we regard the Earth as electrically neutral, that's why you put an Earth wire to stop you getting electrical shocks. But it depends what your net positive or net negative charge is measured to the relative to. So, if you want a safe electrical conduct current going from your socket to your toaster, you want it to be neutral relative to the environment around you which is the ground. So although that is technically a negative charge relative to cosmos, it's all the same charge level as your toaster. So you can touch and get your toast without getting a shock.

Kat - That is a very good idea. So basically, we can't Earth the Earth though, can we, the planet Earth?

David - You could get a big wire and attach it to the sun I suppose but I wouldn't recommend it.

Kat Arney put this to Caroline Steel...

Caroline - So we kind of mentioned this earlier when we were talking about ways to die in space. So, heat does travel through a vacuum. It just doesn't travel in a normal kind of conduction way that we quite often automatically think of. So for something to conduct like when you put a metal spoon in a saucepan and it gets really hot, you acquire particles as the heat energy is transferred through the particles. But heat can also travel through radiation which is part of the electromagnetic spectrum so waves travel from the Sun to the Earth and heat up the atmosphere. So yeah, heat does travel through space and it probably would give you really bad sunburn if you were stuck out there with no suit or anything.

Kat - Is this why things like you get infrared heating lamps and stuff like that?

Caroline - That's also radiation, yeah. So it's a different way of transferring heat. It's using heat waves rather than sort of transferring heat through collisions of particles.

Kat Arney put this to Adam Townsend...

Adam - I was unconvinced so this morning, I did a little experiment so I brought a little present into the studio. Andrew is going to take this one and describe this present to the audience.

Andrew - I've got a secure Tupperware tub and inside it is a small piece of whole grain bread. On it, it has a very definite charred mark in the middle like you've held it against a cigarette lighter.

Adam - Can you smell that here?

Kat - I just got a whiff. That's definitely.

Andrew - It's also very solid and hard.

Adam - It is incredibly solid, incredibly hard. That smell though is the same smell that my flat now completely smells of. So don't try this at home. So I put a piece of bread in the microwave for just 2 minutes and after 2 minutes, the middle just started smoking. And so, you get this nice black burn mark.

Kat - What has happened? A microwave does work by making the water in the food vibrate. So how can it do something that seems like a dry fire?

Adam - The first thing that happens here is that all the water gets evaporated off so you get loads of steam. Microwaves are set the frequency that water is very receptive to which means that water heat up. But all of the stuff, in bread in this case, is still getting slightly excited by the microwave energy. So it's just that water is normally more receptive. So you take away the water. What's left while it still tries to absorb some stuff, some of the starch in the bread for example, and so, it also heats up, and ends up stinking up your kitchen.

Kat Arney put this to Andrew Holding...

Andrew - So I think it's a natural fermenting so you don't need to add yeast like you do with normal bread but that's about as far as I know.

Kat - But presuming it's working on microorganisms from the environment.

Andrew - So, a lots of the alcohol you can make without adding yeast is done by the fact there's yeast on the outside of apples. So, I guess there must be yeast somewhere around the place.

Kat - Exactly. So I mean there's yeasts. Did I say there's a beer that someone's making from Roald Dahl's chair or something weird like that? There are yeasts everywhere so presumably, you could sample them and sequence them.

Andrew - You could sequence for yeast. So I mean, maybe I just know too much about alcohol but the yeasts used in different beers, they're very tightly guarded secrets because if you like took a bread yeast into a random beer, it could taste absolutely awful because they make other things at the same time. That's why marmite could be made with different brewer's yeasts. I'm not sure if it tastes any different.

Kat - Tastes disgusting. But I did go and interview someone. They're making little portable labs called the Bento Lab. I think that one of the people using it is just sampling loads of beers to look at the DNA in the yeast and doing a project on that. So I work out if any beers are related to each other and to trace the yeast's facts so that would be a cool project I reckon.

Andrew - The trouble with small organisms is they do of course evolve. They change their genome a lot quicker. So, if you tried this on bacteria, you probably would have trouble trying to pick a pattern because you find these swapping changes all over the place. They do what's called horizontal gene transfer where they don't just evolve in a linear progression. It hands a gene to its neighbour because they can.

Kat - They swap little bits of DNA, don't they? Because I did have this idea of going around all the recording studios and gig venues in London and taking samples from the microphones and to see what germs are going around.

Andrew - Don't do it.

Kat fills us in on this question about genetic mutations...

Kat - This is a fantastic question because the answer is kind of yes. We will pick up mistakes, changes, mutations whether that's from the processes of life like copying DNA or from the oxygen that we're using to make energy that damages DNA loads and loads, and loads. Also, there are chemicals in the environment and things like ultraviolet light, chemicals in tobacco smoke that can damage the DNA in different cells and that can be propagated if those cells divide. So yeah, we are made up of probably a little bigger or smaller clumps of cells that are all very, very slightly different. Obviously, a good example of where this really goes wrong is cancer because that's when cells have picked up a number of mistakes that have made them start growing out of control.

Caroline clears up confusion about cars in thunder storms...

Caroline - It is a good idea to be in your car in a lightning storm. So, static shocks happen when two materials rub against each other and charge transfers from one to the other. So this could be when you sat in your car wearing some synthetic material and it rubs against a car seat and you build up a negative charge and then you innocently reach out to grab your car door handle and the negative charge from you discharges through the car and makes a sort of nasty shock. But lightning, it's a good idea to be in your car if there's a lightning storm because if lightning were to strike the outside of your car, the lightning would travel through your car body and not actually harm you. That's because the car - well provided your car is made of metal - the current will want to travel through that because current likes to go through the path of least resistance so it will travel through the car, to the ground, shielding you. This is often referred to as a faraday cage.

Kat - You've got rubber tires as well. Is it something like you're meant to wear wellies as well in an electrical storm?

Caroline - So, the rubber tires thing is quite often - it's been a myth. It's an easy answer to why you should get in your car but that's not really why because the current does still flow through the tires to the ground. It does discharge. But yes, if you're wearing rubbing shoes, rubber is an insulator so you're slightly more protected from an electric shock. Because it just makes a bit more of a resistive path for the current to travel and it's less likely to travel through you.

Kat - Adam.

Adam - How do I stop getting shocked by my car?

Caroline - So, you could buy a non-metal car which is an option.

Caroline - Or you could wear clothes that sort of build-up static charge less. The cheaper more plastic clothes build up stuff that charge more.

Kat - You're wearing like nylon. Stop wearing the nylon '90s.

Caroline - Yeah, nylon is bad plan. I remember I used to have a dressing gown that I could build up such a static charge on by rubbing it against the carpet that if you turned off the lights, you could actually see the little electric discharge if you touched it, so don't wear that dressing gown.

Adam - No driving with dressing gown.

Caroline - No driving in dressing gowns. Go for sort of - I'm not sure what materials are not good at building up charge.

Kat - Linens, cottons.

Caroline - Imagine stuff like silk and things like that would be fine. You can get silk suit.

Adam - Silk trousers.

Caroline - Silk suit and a wooden car, and you're absolutely fine.

Kat - No chances of electric shocks.

Adam - Thanks very much.