What keeps the Earth's core so hot?

What keeps the Earth's core so hot?

It's a combination of things. One, the earth's quite a big planet relative to Mars which is a bit smaller. There was a lot of heat that was in the Earth to start with. When the planets were first forming around the sun in what's called a protoplanetary disc a lot of the swirling and spinning material was crammed together and squeezed together. It had a lot of heat from that, those frictional effects. Also the Earth has what's loosely termed as radioactive compounds in the Earth. As these radioactive compounds break down and decay they produce heat. The heat is obviously concentrated in the core of the Earth and then filters up towards the surface. Because the Earth's a big planet it's got a big core. It's got lots of radioactive decay going on. Some of the heat that we're seeing is because the Earth is sustaining it's own heat by radioactive decay.

How can we tell what noises the dinosaurs make ?

How can we tell what noises the dinosaurs make ?

The reason you hear those sounds on TV is to make it more interesting. We know dinosaurs probably made noises because they had very good sense of hearing. If you look at dinosaur fossil skulls, you can trace their ear canals and work out where their ears would have been and the kinds of sound they would have responded to. If they could hear sounds, they could probably make sounds. In the late 90's scientists put a fossil through a CT scanner to look at the bone structure. The headpiece was a series of intricately connected tubes a bit like organ pipes. They analysed the structure of these canals and airways, and used a computer to model what would happen if air were blown past. They found that the dinosaur could probably have produced low pitched rumbling noises that could have carried a long way. So what we use for dinosaur sounds on TV is what can be inferred from studying the shape of their fossilised remains, with a bit of artistic license thrown in.

Why do mints make your breath feel cold ?

Why do mints make your breath feel cold ?

According to a group of scientists in San Francisco, the reason is that the same nerve fibres that signal hot and cold are also sensitive to menthol, an ingredient in mints. Normally when the temperature changes it causes pores on the surface of the nerve cell to open and close, changing the electrical activity of the cell, which the brain interprets as a change in temperature. But menthol can also affect the function of the pores in the same way and triggers the nerve cell into thinking that the temperature is lower than it is.

Who is sweatier, men or women ?

Who is sweatier, men or women ?

Men are definitely sweatier than women. Previously this was put down to the larger male stature, but a team of scientists at University of Dortmund, Germany, led by Barbara Griefahn, say different. In their laboratory they have set up a mock 'sweltering car'. 'Volunteers' sit for up to 2 hours under heat lamps, mimicking the effect of the sun beating down through the windscreen. Under these conditions men lose about 250 mls of sweat per hour during the experiment, 70 mls an hour more than female volunteers. This makes them officially sweatier, even allowing for size and weight, say the scientists.

Is it normal for you to have a body temperature lower than 36.7celsius ?

Is it normal for you to have a body temperature lower than 36.7celsius ?

Normal body temperature is 37?C. This is set by part of your nervous system and the hypothalamus, which is found in the brain stem. The hypothalamus monitors your body temperature and changes it if it becomes too hot or too cold. Your body temperature doesn't have to be exactly 37?C: exercise can make you hotter, while going outside on an icy day can make you cooler. The place in which you measure your temperature is very important. Putting a thermometer under your armpit will show you your peripheral temperature, and this can be quite a bit lower than your 'real' body temperature called your core temperature, or the temperature at the centre of your body. This varies very little at all in day to day life. It can best be measured by putting a thermometer in your bottom! You have to get very cold to change your core temperature, such as being stuck in freezing weather for a long time. People who have a drop in core body temperature have what is known as hypothermia. This makes them drowsy, and if left untreated, they will eventually become unconscious. When the body is cold, the chemical reactions that provide your cells with energy don't work as well. This makes cells function abnormally and, if prolonged, can be fatal.

Does the nicotine vaccine stop the cravings to smoke?

Does the nicotine vaccine stop the cravings to smoke?

Probably not. The mechanism works by stopping the effects, and so might actually increase the cravings. The vaccine is probably best used in combination with something that helps with the withdrawal symptoms. However, by stopping the effects, it also helps to break the cycle of reinforcement. Eventually this may lead to people stopping people smoking because it does nothing to help the cravings.

Which bacteria or viruses cause ear infections ?

Which bacteria or viruses cause ear infections?

The ears have the same linings and are connected to the nose and throat through the eustacian tube. This means that any of the viruses that cause colds and sore throats can get through into your ears. Viruses are the main invaders, but bacteria can cause secondary infection. They seize the opportunity to invade after a virus has caused the initial problem - such as damaging the protective lining of the airway, or blocking up the eustacian tubes in your ears with mucus.

What causes narcolepsy?

What causes narcolepsy?

Narcolepsy is the disorder where people fall asleep repeatedly during the day and there seems to be genetic component to this. Luckily there are drugs which can be used to treat it. There can be frightening aspects to narcolepsy, for instance people have been known to suddenly fall down as they fall asleep, or have nasty hallucinations as they fall asleep. The brain chemistry behind it is better understood now, and we do know about the genes that are linked to this. One particular chemical is a substance called hypocretin, and people with narcolepsy tend to have problems with the receptors for this brain chemical, or an abnormal form of this chemical. There are also people with 'clock' genes that give them a faster or slower body clock, but this shouldn't be mistaken for narcolepsy.

Would someone with a psychiatric disorder be better able to pass a lie detector test as they may not feel remorse?

Would someone with a psychiatric disorder be better able to pass a lie detector test as they may not feel remorse?

Old-fashioned lie detectors like the polygraph only detect stress. If the lack of remorse meant that the interviewees had reduced stress levels that would help them pass. Our lie detector, Silent Talker, makes its judgement on non-verbal behaviour: crudely what people call body language. Silent Talker can detect stress but lying involves other factors. We can only juggle a certain number of mental variables at once while we’re thinking. If we’ve got to try and maintain a whole load of different factors about an imaginary story it’s very difficult to do all the mental processing to keep that consistent. That’s what’s known as having a high cognitive load which affects non-verbal behaviour. Also duping delight occurs when liars get a kick out of getting a lie across successfully and again this affects non-verbal behaviour. In one of our own experiments on the general population we taught silent talk to recognise guilty feelings the participants felt while they were lying. When we added this information to the general lie detection we got more accurate classifications. In another independent study conducted by a different university using Silent Talker it was found that Silent Talker was effective at detecting lies told by psychopaths in interviews. So there we have it: evidence that remorse is a factor in the general population but also evidence that in the case of one disorder it’s not the only factor.

Why do we laugh when we find something funny?

Why do we laugh when we find something funny?

Something that’s funny is by definition something that makes us laugh. I’ll talk about why we laugh. Laughter is really a social phenomenon. If we look back to its origins, laughter, the ‘ha ha’ originated in the ‘pant pant’ of rough and tumble play such as you would find in tickle or the rough and tumble play of children. ‘Pant pant’ became the human ‘ha ha.’ With adults, however the arena of laughter has shifted from tickle and rough and tumble to a more linguistic and cognitive arena whereby, for example, the play of adults has to do with wordplay during conversations. You don’t have to tickle one of your colleagues to get them to laugh. You can tell them the joke. Even within conversation the key to laughter is the presence of another person. Laughter almost totally disappears when we’re alone. The key element for producing laughter is another person and not a joke. In fact we have followed people around and recorded what was said before people laugh. In only 10 or 15% is it anything remotely joke-like. Most laughter follows comments like ‘hey, where have you been? Ha ha!’ or ‘I’ve gotta go now, haha!’ These aren’t jokes so it basically is about developing bonds and relationships with other people.

Why does one get cramp?

Why does one get cramp?

Cramp is a muscle spasm and we don’t actually know what cramp is. We just know that if people have regular cramps – and it tends to happen quite often at night and it tends to happen in younger people more often than older people and it tends to be relieved with quinine, the same stuff that makes tonic water taste nice. A muscle spasm is when some of the muscle fibres – because a muscle isn’t just one homogeneous giant thing. It’s actually made up of lots of individual little muscle fibres. Some of those muscle fibres go into a spasm. In other words, the contract more than they should and they lock in a contracted state. Surprisingly, muscle actually takes energy to relax, not to contract. When a body of a person dies, they go into rigor mortis because the cells in their muscles run out of energy and their muscles can’t relax and they stay rigid. That’s why a person gets rigor mortis. If you leave them a bit longer then the rigor mortis goes away again when the muscle breaks down and starts to relax. What cramp could be is for some reason that clutch of muscle fibres don’t have enough energy in them, perhaps because there’s been a reduction in blood flow that’s insufficient for the muscles needs. Therefore the muscle runs a little bit short of energy and this trips its inability to relax properly and you get a cramp. Rubbing a muscle and massaging it to get the blood through it can make it better.

Why do we wake up when we need to urinate?

Why do we wake up when we need to urinate?

It’s the same reflex if you need to roll over in bed when you’re uncomfortable. If you stayed in one position in bed all the time all night you would get a pressure sore because the pressure of tissue against the bed would stop blood flow through that area. As a result you would end up with a de-vascularised bit of skin and it would necrose. Patients who are left in one position in hospital for too long get exactly the same problem. The body has a series of reflexes programmed into it even when you are asleep. You can react and respond to various stimuli with an appropriate thing. If you’re getting uncomfortable in bed you can roll over. If, on the other hand, your bladder’s getting full then your brain says wake up, you need to go to the loo. It’s an automatic reflex. Some people lose that reflex as they get older. Some people when they’re very little actually wet the bed because it hasn’t developed yet. That’s why little kiddies have to respond to those signals the right way. That’s all about potty training and bladder training.

Why are Australian snakes so much more toxic in general than other snakes in other parts of the world?

Why are Australian snakes so much more toxic in general than other snakes in other parts of the world?

The idea that Australian venomous snakes are more toxic than those anywhere else is, to a large extent, a myth which started out with a study that was published approximately thirty years ago. They took 25 different snake venoms and showed that the top ten of those were Australian. It only included five non-Australian snakes so it’s rather like the American baseball World Series: you can’t lose if you don’t include the competition. In reality the two snakes in the world with the most toxic venoms drop for drop are in fact Australian. Immediately after that when you look at the table of most toxic venom's you start having a large number of other snakes coming in. A large number of Australian venomous snakes are actually not spectacular at all in their potency of their venom. There’s nothing intrinsic about Australian snakes being particularly toxic. The amazing thing is that the snake with the most toxic venom in the world – the inland Taipan has never actually killed anyone. Some snakes live in remote areas and in places where there is no medical treatment and other snakes live in areas which either are very remote and people don’t go to so they don’t bite anyone or there is good anti-venom and good treatment available. If you’re bitten in Australia a flying doctor comes and picks you up and you go to a hospital and 99.5% of cases everything’s going to be just fine. If you get bitten in West Africa then there is no anti-venom, there is no hospital that can treat you and you slowly bleed to death from a snake that has a fraction of the killing power.

Could the retina be repaired using stem cell research?

Could the retina be repaired using stem cell research?

In the last twelve months we’ve seen evidence that perhaps it can. The stumbling block at the moment is that perhaps we don’t have the stem cells necessarily, ethically, to do it. Scientists in University College London published a paper in the journal Nature about this time last year. They took mice which had been genetically programmed develop a disease like the human disease, macular degeneration, and they took stem cells from the retina of newborn mice. They implanted these stem cells into the eyes of the mice that had macular degeneration. They were able to show that the mice got back their ability to see. By following where the stem cells went in the eyes they found that they migrated to the right part of the retina and turned back into photo-receptors. These cells take the light and turn it into information that the brain can understand.

Sharp Sounds Damage Hearing?

Which is worse for your hearing - the short sharp sound of a hammer, or the constant drone of a chainsaw?


Whenever you listen to sound, the sound actually hits the eardrum. That sound is actually amplified by a series of tiny little bones in the ear called ossicles. These ossicles vibrate and stimulate the float within the cochlear which, in turn converts the sound energy into electrical energy which is perceived
as noise by the brain.

There are two different types of noise induced hearing loss. You have acute stage hearing loss, for example due to a large explosion or you may have something more gradual. This is more common in most people. This gradual increase in hearing loss is a combination of both the intensity of the sound as well as the duration of the sound. So for example, someone who shoots guns for a hobby may be exposed to very short bursts of noise but very high intensity and they may experience a similar degree of hearing loss compared to someone who's in a slightly different environment where the sound intensity's actually much lower but much more constant (e.g. the mining industry). There are also additional factors that can influence noise induced hearing loss. It's not just the combination of noise because people's tolerance to noise varies. Therefore there's some genetic influences in this as well. Noise induced hearing loss is not just the simple of noise experienced but also the genes that influence your hearing.

If you get cold sores and give blood, can the virus be passed on?

If you get cold sores and give blood, can the virus be passed on?

There’s probably almost zero chance of that. The virus that causes cold sores, the Herpes Simplex Virus (HSV), most of us acquire this when we’re very young because of our parents kissing us and children dribbling over each other in nurseries – it spreads in saliva. When you first get it, it produces a sore throat, ulcers in the mouth, swollen glands in the neck and a high temperature. It then invades the sensory nerves that supply your mouth and tongue, as well as other parts of the body it can infect. It goes inside these nerve cells and switches off. It exists there as a piece of DNA, loitering alongside the cell’s own DNA, and periodically comes back to life. We don’t know exactly what triggers it to come back to life, but we know that things like damage to the skin, for example sunburn, menstruation, depression and immune depression, can bring it out again. The virus turns back on its DNA, makes new virus particles which come down the nerve and pop out of the skin, causing the infectious lesion, the cold sore. When you kiss someone who’s got one, that’s how you pick it up.

Thankfully, it doesn’t really get into the blood stream, so you should be safe from HSV from blood products. Other members of the herpes family do spread through blood, but not HSV.

What causes sleep apnoea?

What causes sleep apnoea?

You are lucky to have had it diagnosed because lots of people with it and are undiagnosed. People who have apnoea stop breathing, maybe hundreds of times a night, which means that your brain is regularly starved of oxygen producing symptoms of tiredness, poor concetration and irritability the next day. There is a way of treating this and that is to wear a mask which pushes air down into the lungs under pressure - maybe your doctors have told you about this - but you'd need to use this every night for life. There are two possibilities for what causes sleep apnoea: central apnoea is where the bit of the brain which tells you to breathe whilst you're asleep switches off - but this is rare. More common are problems in the throat so when you fall asleep your muscle tone goes away and your throat collapses, obstructing the airway. This is why pushing air down with a mask can help. People who have this can have surgery to correct it, but the surgery is fairly major.

What are the risks associated with tubal ligation and vasectomy?

What are the risks associated with tubal ligation and vasectomy?

Tubal ligation means that you go inside the peritoneal cavity in the woman, in the pelvis. You identify the fallopian tube on each side. You can see that quite easily because they’re about 5 mm across, and you clamp them. You put a very large paper clip which is squashed onto the tube, and it crunches the tube closed. And the idea of that is that then what it does is basically squashes the tubes so that the egg released by the ovary cannot make its way down the tube to get into the uterus. And at the same time, a sperm cannot get along the tube to meet the egg and fertilize it. Otherwise, you might get the risk of what’s called an ectopic pregnancy, the actual egg starting to be fertilized and grow outside the uterus.

The risks of tubal ligation are that it doesn’t work. It’s a small risk but there’s nonetheless a risk that you could fail to completely close off the pathway. Another possibility with any invasive procedure is, of course, that you can cause pain. You could cause bleeding. You could get a localized infection.

With vasectomy, it's a very safe procedure, pretty similar though. You basically are cutting, folding back on themselves and tying off the vas deferens, which are the tubes that carry sperm from the testicle up inside the body. The idea being that then you interrupt the route that the sperm will follow after the testes. The risks are pretty similar to having tubal ligation and the fact is that occasionally there is incomplete severance. There may be a route by which sperm can still make it through. Also, you don’t stop being fertile. The minute you have it done there’s a flush out or a washout period afterwards.

And so if someone just has a vasectomy and then assumes they’re now no longer capable of fathering children, they could be in for a shock.

Why is it that stars appear spiky and not spherical? And why do they twinkle?

Why is it that stars appear spiky and not spherical? And why do they twinkle?

The main reason that stars look spiky is that the optical instrument you are looking at them with is not perfect. Because light is a wave, if you shine it through a small hole you get a pattern known as an interference pattern, this is because different light waves interfere with each other, making patterns of light and dark.

If the hole was circular you would get a relatively clean picture, but if it isn't then you will get various visual artifacts. These are much dimmer than the object itself so during the day you can't see them, but if a bright object is surrounded by darkness they are very obvious.

So if you look at a streetlight you often see streaks coming off it. If you squint, you make your pupil even less circular so the streaks get much stronger. The interference pattern will have a similar symmetry to the hole, so if you squint your eyes into a slit you get 2 strong streaks. Your camera doesn't have a perfectly circular aperture so you get streaks, the number will depend on the shape of the aperture.

Large telescopes need structures to hold their secondary mirrors, and it is the diffraction from these that you see in pictures from the Hubble Space Telescope etc.

But the reason they’re actually twinkly when we look at them is nothing to do with that. They’re twinkly when we see them through the Earth’s atmosphere because the Earth’s atmosphere is not uniform. There’s air which is at hotter temperatures, and therefore, less dense, and there’s air which is at colder temperatures, and therefore, more dense. And when light goes from a medium, which is more dense, into a medium which is less dense, it changes speed. In fact, it speeds up a bit. And it’s that change in speed that causes the light to bend a little bit. And that means that when you see rays of light coming from a long way away, they appear to be coming from one place, and then another place, and another place, and then another because the light rays are being bent alternately as it goes in and out of warm and cold patches of the Earth’s atmosphere. And that’s what makes the star twinkle. And you see the same thing happening if you look at the lights from a harbour across a sea harbour or a port, for example.

What is it that keeps planets spinning, as well as keeping them moving in their orbits?

What is it that keeps planets spinning, as well as keeping them moving in their orbits?

Well, it’s a fairly simple piece of physics. One of the things that keep on moving their orbit, there’s nothing to stop them. They’re not hitting anything, so to speak. So they’re not losing any energy, and they’re not losing, more importantly, angular momentum. So angular momentum is a conserved thing. It can’t just be taken away by, just by wishing it away. It has to be taken away by things, and the Earth is just sitting there, rotating. Nothing’s taking its angular momentum away except the Moon. The Moon is actually going to steal some of the Earth’s angular momentum, slow it down, and at some point in the future, the Earth and the Moon will be locked together they would both have lost angular momentum. At the moment, we only see one face of the Moon. In the future, only one face of the Earth will be facing the Moon. So we’ll only be able to see the Moon from one side of the Earth, and vice versa.

Do bacteria have intelligence? How do they find their food?

Do bacteria have intelligence? How do they find their food?

Bacteria have no brain, but on the surface of a bacterial cell there are receptors for different chemicals. This means that they can tell which way to travel by comparing, chemically, how many of those receptors have things that they like attached. They assume that the side with the most ‘good’ receptors filled is closest to their food. They use this concentration as a guidance mechanism to control where they go.

Bacteria travel towards desirable chemicals, or away from toxic ones, using a flagellum. This is like a propeller, powered by a protein ‘motor’. When the ‘motor’ burns energy it causes the protein to change shape, quickly spinning the long ‘tail’ part. This lets bacteria move so quickly that they are officially the worlds fastest swimmers, and can travel 60x their body length in each second.

Why do different types of meat get different colours when they’re cooked?

Why do different types of meat get different colours when they’re cooked?Beef turns dark brown, pork light brown and chicken turns white. Most fish are also white, except for Salmon and some other red fish. What makes the difference in the colour?

Its down to a chemical called myoglobin. Myoglobin is a bit like haemoglobin, the red coloured stuff that ferries iron around in the bloodstream, except myoglobin is locked up in muscle (and meat is muscle). Red meat contains a lot more myoglobin than white meat, as the muscles that tend to be red are the ones most active in an animal. The legs of a standing animal will be redder, and have more myoglobin, as the muscle has been tuned up for long term activity.

Muscles that aren’t used as often, fast-twitch muscles, tend to have low blood supply, little myoglobin, and therefore little colour (white meat). Chicken breast and wings don’t get a huge amount of use (as chickens don’t fly), and so they are white muscle.

With fish, most of our salmon has a red colour because we tend to buy farmed salmon, and to keep the meat looking a healthy colour the fish are fed astaxanthin. They would get this in the wild environment from yeast and from algae, it’s an antioxidant similar to the chemical which makes carrots orange. Shrimps eat the algae, salmon eat the shrimps and the colour passes through the food chain.

Everybody knows that salt melts ice. Why are there such big icebergs in the sea?

Everybody knows that salt melts ice. Why are there such big icebergs in the sea?

Salt makes ice melt at a lower temperature. So in sea water ice will melt at maybe -5 or -6 degrees centigrade. But if you get cold enough, the water will still freeze. And so you can still get icebergs. It's just got to be a bit colder than if it was in a lake. When there's salt in water, the water can get a bit lost in the salt. It gets in the way of the water forming a crystal. It's more difficult for the water to form the crystal, so it has to be a bit colder for it to actually freeze.

Should coffee be stored in the freezer?

Should coffee be stored in the freezer?

The main reason you want to freeze it is to keep in all the volatile chemicals and aromas. If you keep it in a warm place then the volatile chemicals come out of the coffee and it won’t taste as good.

What's actually happening when you fry food?

What's actually happening when you fry food?

Its called the Maillard reaction after a French chemist Louis Camille Maillard. This is a chemical reaction between carbohydrate groups (that's sugars largely) and protein or amino-acids (those are the building blocks of proteins). It takes place at around 148 degrees and when these sugar groups lock on to the amino-acid groups they form these nice, brown caramelised substances which taste great – that's the nice aroma you get from cooking. As it happens at 148 degrees – that's 48 degrees hotter than water boils at – that's why you get a very different consistency and taste and texture to fried food compared to boiled.

How do cats purr?

How do cats purr?

Now, there isn’t really a special purring organ in a cat. It’s simply a very fast movement of their voice box. So it’s fast twitching of the muscles in their larynx which rapidly kind of flap up and down something called the glottis. That’s some little flaps inside your throat, and it causes air vibrations when you inhale and exhale. And interestingly, a fact for you is that tigers, lions, jaguars, and leopards can only purr when they’re breathing out!