Helen -  No their ears probably don't pop because in fact, unlike a scuba diver who takes down a tank of air and breathes it at pressure that is equal to the water around them—which becomes very high very quickly as you go down—submarines are pressurised so that inside them they maintain the same pressure as air at the sea surface (1 atmosphere or atm: the unit we use to measure pressure).  Whereas when you're scuba diving, you could be breathing air at something more like 20 atmospheres, which is much more dense.  It’s that pressure that makes your ears pop and you haven’t got that in submarines.  You may get a bit of compression as you're going down in a submarine as some of that pressure from the water is pushing in on the metal structure and the air inside.  But I think that’s fairly minor, I imagine. 
They build submarines fairly tough so that they can withstand all this pressure without collapsing inwards.  So no, submariners don't have popping ears and interestingly and importantly, it means that if you have an accident, deep down and you have to escape from a submarine, you won't get the bends because you haven’t been breathing air at pressure.  You haven’t filled up your system with nitrogen which will then bubble out of your blood if you're scuba diving and you come up too quickly.  Same thing doesn’t happen in the submariners.  Submariners are trained to be able to hold their breath for long enough to swim a long, long way up from the bottom of the seabed to the surface and survive if there’s a problem down below.

Chris - Well actually, scientists have done this in a number of ways.  In one instance, there was a complete head transplant done on a chimpanzee where the brain and head from one animal was grafted onto the blood vessels of another, recipient, body.

Now that’s all well and good in the sense that it keeps the brain alive because the blood supply is preserved, but what it does involve is severing the connection between the brain and the spinal cord, which is how all the information gets into and out of the brain pretty much.

That means that the animal is destined to have no mobility and no ability to feel incoming information from the rest of its body.  So, scientists, if they were going to do head transplants would have to surmount that one.

But, there are limited neuronal grafting and transplant studies being done because there are some neurological diseases, specifically neurodegenerative diseases, which are associated with the death or loss of certain subclasses or groups of nerve cells in the brain.

So scientists have reasoned that, if you're losing certain populations of cells in the brain, perhaps what we need to do is to put new cells back into that bit of the brain and perhaps they will wire in and they can do the job that these cells that have been lost used to do.

A good example of this is Parkinson’s disease, because we know that one specific group of cells that make the chemical dopamine are lost from the brain in this disease.

Scientists have now done a number of experiments where they take foetal brain tissue - and you need foetal brain tissue because this seems to be critical because the cells seem to have a more robust phenotype – in other words, they seem to survive better – and if you harvest those cells that are destined to become dopamine-producing nerve cells in foetuses and you put those into the brain of an individual with Parkinson’s disease, into the part of the brain that is lacking dopamine, in other words, is affected by the disease, the cells seem to have the ability to survive to a limited extent, and also, wire themselves in and produce dopamine to make up for the shortfall.

So, scientists are doing that with Parkinson’s disease.  They are also looking at the disease, Huntington’s disease, which is another neurodegenerative disease but is caused by the loss of a different class of nerve cells.  So they're trying similar tricks there.

It’s early days, and the results have been mixed, but they do show promise and so we think that there is a good reason to be pursuing this.

Helen -  Well, I think some people would answer so they can paint them pretty colours, and that way nails can be part of the way you attract a mate. But in fact, if you look around, lots of different animals that we’re related to, lots of other mammals, also have fingernails or claws. And they’re all very useful.  And we also have them probably because they are useful tools. If you think back to our ancestors when we first evolved as humans, fingernails can be very useful for picking things up – picking the skin off a fruit, say, for scratching an itch.

If you went to see how useful they are, put a sticking plaster or tape over your nails and see how you lose that ability to use your nails as tools.  That’s probably why we still have them.  Why do we have toenails?  Probably, because our ancestors, chimpanzee-like creatures, also use their feet for manipulating objects and a toenail helps to give you grip.  So really, nails are 20 little tools for us to use in our daily lives and that’s why we still have them and indeed, I'm glad we do – it can be very painful without them.

Well yes, it definitely is and people are doing exactly that with things like toothbrushes.  You might have seen these toothbrush devices where you plug the toothbrush device into some kind of base station or holder, but there’s no obvious electrodes.  And what’s going on there is it’s using a magnetic field to convey the energy from the base station into the handset and then from there, into the battery.  So what you do is have a coil in the base station which passes an electric current through it, generating a magnetic field and you pass an alternating current through it so that the magnetic field is changing.  You then have in the base of the object you want to charge, another coil which you put into the magnetic field which is created by the base station.  That’s what’s happening when you're docking one into the other.  The magnetic coil in the device therefore sees this changing magnetic field which induces an electrical current in the handheld device.  That current is then fed into some kind of rectifier, to turn an alternating current into a direct current and it’s then used to charge a battery.  And that happens with things like toothbrushes, there are certain shavers that work the same way.  Doing it over a greater distance would be really, really inefficient because the magnetic field decays as 1/r² so, inverse square law over distance and therefore the amount of energy you'd have to put into the coil would be huge in order to charge things at a remote distance.  So it’s useful over small distances, it’s not very good over long distances. 

Helen - Well, I'm afraid in fact that there are lobsters in the Pacific.  In fact, there are various different species of spiny lobsters which don't have big claws like the American lobster, Homerus americanus, which does have big claws.  That’s one from the Atlantic but there are some spiny lobsters including the California or red rock lobster, Panulirus interruptus, and there’s also one called the green spiny lobster, and they do live on the Pacific, from California, down through into to Peru and out into the Pacific as far as the Galapagos Islands.  There are various species that do live there.  I assume when you say you like lobsters, you like to eat them, and that’s fair enough - they can be quite tasty, but some populations of lobsters around the world are very heavily fished and therefore, aren’t lots of them around for us to carry on eating. And that could well be the case in California for some of these species.  Although in fact, down in Mexico, in Baja California, there is a fishery for the red rock lobster which, about five years ago, was labelled as sustainable by the Marine Stewardship Council. This means that fishermen down there are keeping within sustainable catch levels so there should still be a healthy population in years to come.  So if you do want to eat Pacific lobsters, I would definitely send you to Mexico to try out the red rock lobsters down there.

Chris -   It’s a very good question and there’s obviously some important science there for the simple reason that it doesn’t matter what you look at, most of these objects are round, absolutely. 

The simple answer is it’s down to gravity.

If we take our own solar system as a really good example, you have the Sun in the centre and that’s round, and the reason that’s round is because a big ball of gas collapsed in on itself and squeezed hard enough to start fusion.

Around that ball of gas would’ve been initially an envelope - like a shroud - of material comprising dust, debris and gas, which slowly condensed into a disk called a proto-planetary disk.

 Over time, all of this material, thanks to gravity - which is a function of mass - would’ve pulled this material slowly together. It would have accreted - or got together - and slowly would’ve built up planetessimals, miniature planets, and then they grew to make big planets as they hoovered up - under increasingly powerful gravitational fields - the rest of that residual material.

Because gravity is pulling things together, everything that’s being attracted wants to get us close to everything else as it can.  The most effective way for that to happen is if objects are spherical. 

It’s the same as a raindrop, because water wants to get us close to other water molecules as it can without being in contact with too much air. That’s why raindrops form round blobs, not a flat sheet of water - this way, as many water molecules can get as close together and stick together as they can.

That’s also what’s happening with these nascent planets, or other objects in space.  The material squeezes together, and the way in which you can get as much material in as close a configuration as possible to other material is if it’s a round shape.

Now, if you go in at high resolution and look closely, obviously, there’s not a perfect round surface because the Earth has mountains and things and so does Mars - it’s got Olympus Mons, a giant volcano.

But, to all intents and purposes, at low resolution, these things are round because gravity has made them that way.

Helen -   It’s a great question and it’s something that’s being talked about more and more in the news as we hear about the emptying oceans and fish stocks being depleted.  In fact, I had a look at this question and our listener comes up with a nice idea, in fact a brilliant idea of “couldn’t we just give the oceans a rest?  If we perhaps blocked off bits of the ocean from fishing for say, 10 years or so, we could rotate around and the oceans would replenish themselves.  Could they?” 

Yes, they could indeed.  In fact, what you're talking about are marine protected areas or marine reserves this is the sort of tool for ocean management that’s being talked about by governments and by conservation groups. Because we know that if you leave a piece of sea alone from the impacts of us people catching so many fish, it will very quickly recover.  It’s extraordinary how resilient the oceans can be and it does offer us some hope.  The question is, can we actually get this done?  I love the idea of blocking off and rotating parts of the ocean that we can have as these protected areas, if only it could happen.  At the moment, less than 1% of the oceans are protected from human activities and there are various estimates as to how much we should protect in order to have a resilient ocean that keeps itself going: that’s up to as much as 30% or a third of the oceans.  If we could do that, then we would have much better chance of ensuring that fish stocks and all sorts of other marine creatures will still be around in years to come.  So, let’s hope we can do that and we can achieve resilience in the ocean because I think it will fight back but we need to give it a helping hand.

Chris -   The Moon is pretty close.  It’s about a quarter of a million miles to the moon and it’s about 100 million miles to the Sun, give or take.  

So, when the Moon is on one side of the Earth, closest to the Sun, it’s about 99 and 3 quarter million miles between the Moon and the Sun.

When it’s around the other side, so the Earth is between the Sun and the moon, then it’s about one hundred million plus about a quarter of a million miles, so a hundred and a quarter million miles between the Sun and the Moon!

Chris -   If you've noticed, when you turn the shower on the morning, the cold water comes through from the pipe first and it will splash and sound different against the bottom of the shower compared with when the hot water, which comes along shortly afterwards, comes in; the note will change.  This is a real observation; your ears aren’t deceiving you.

The reason for it is that water changes its viscosity - its stickiness - according to its temperature.

If you could zoom in with a really powerful microscope and look at some water molecules, what you’d see is they are shaped like miniature boomerangs.  At the apex of the boomerang you would see an oxygen atom and on each of the arms, you'd see hydrogen atoms. 

Oxygen loves electrons, so it pulls the electrons of itself and the hydrogen towards itself very tightly, and that makes the oxygen a bit minus. The hydrogens are correspondingly therefore a bit plus. 

As a result, when water molecules are sitting together side by side in solution, the positively charged hydrogens are attracted to the negatively charged oxygens of an adjacent molecule and this is called hydrogen bonding.  It makes water sticky, and it gives it some of its special properties that in fact help it to make life happen on Earth. So it’s pretty important that this happens. 

But, when you heat the water up, the particles start to move much more quickly.  They have more kinetic energy which is a function of the temperature.  This means that they're zipping past each other much faster.  They're therefore gluing onto each other less well and this makes the water runnier or less viscous. 

So when it comes splashing out of the shower and hits the shower pan, the water fragments into smaller particles and makes a higher pitched splashing noise than when it goes into the cup or goes into the sink when it’s cold. 

Have a listen next time you're in the bath for the shower and you will see that the note is different.

Chris -   Now that’s a fantastic question.  It’s the same science behind why clothes look a bit darker when they're wet than when they're dry.

The reason that this happens is because when you have paint in the tin, the paint is mixed with some kind of solvent - usually water or oil or something, which makes the paint easy to spread onto the surface so you get a nice even coat. 

When you paint the paint onto the wall, it’s got all that solvent in it. The solvent then evaporates off - dries - and this leaves behind just the particles of paint on the wall.

Now, the particles, if we take white paint as an example, are usually titanium oxide; they’re very, very white.  These particles are roughly the same size as the wavelength of light, which is why they reflect and scatter lots and lots of wavelengths of light back at you, which is why you see a white surface.

But when the paint is wet, those particles are surrounded by little droplets of water or oil (the solvent). And so, when light goes in, it doesn’t see these tiny particles of roughly the same size as the light wavelength; instead it gets subjected to a bit of refraction through the fluid and that buries it deeper into the wall surface, rather than reflecting it back out at you. 

So, if it’s darker of course, what must be happening is less light is being scattered back towards you than being absorbed and that’s why it looks darker. 

Once that effect goes away (when the solvent evaporates) and you've just got the particles there, you're scattering more light back at you, so the paint looks brighter.

Chris -   Most of them have got activated charcoal in them.  All that means is that it’s charcoal with a big surface area, and this means you've got carbon, which can soak up noxious odours.

So you have something that can lock away odours, that’s the first point, and it will also do another thing, which is soak up water.

Your feet squirt into your socks something like a quarter to half a litre of sweat every day.  At the same time, you've got skin cells falling off at the rate of thousands every second from all parts of your body, but your feet especially because the skin on your feet is a bit thicker. 

So what you've got are all of the elements of the perfect microbiological or bacterial banquet going on on your feet:  you’ve got food in the form of dead cells, you've got water in the form of sweat, and you have warmth.

All these things add together to very active, hungry bacteria being well fed. Consequently, they produce various chemicals, some of which are whiffy – smelly; they're volatiles.

But if you put these odour eating things into your shoes, they soak up the water for a start, which means that there’s less to keep the bacteria lubricated so they don't grow as well, and they also soak up some of the noxious gases because they have a big surface area and they can adsorb those materials, which prevents them from being so pungent. 

So they work in a number of ways, but that’s chiefly how it does it.

Helen -   Wonderful creatures indeed!  Although keep your distance, of course, because they are nasty stingers, but they're beautiful things to look at.  I think this question is based on the fact that our listener knows that these animals are not in fact jellyfish.  They're not single living creatures like that but they're colonies of lots of little creatures that live together. They belong in the same phylum, the Cnideria, as jellyfish and they look similar but they are in fact different.  Portuguese man of wars are called siphonophores and they're made up of three main different types of little animals that live together.  There are dactylozoids which make up the tentacles, there are gastrozoids which are the bits that eat the food, and there are gonozoids, and they are the bits of these creatures that reproduce.  They produce sperm and they produce eggs.  In fact, you get female and male Portuguese man of war, even though they’re called “Men”. The sperm will fertilize eggs in the water colum to produce larvae which grow into bigger Portuguese man of war.  And the way that they grow from those individual cells is by asexual division of those cells and they produce all those individual three types of animals that live in this one colony and drift around the oceans, stinging things and eating things as they go.