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Friday, February 5, 2010

Can lightning re-start your heart?


Can lightning re-start your heart?

Firstly the short answer is yes, it is possible that being struck twice by lightning would firstly stop your heart and then restart your heart. The answer is a bit more complicated than that though. The heart cells maintain a voltage drop across them which controls the inflow and outflow of ions. These ions allow the heart to beat. If the heart’s struck by lightning that voltage drop is immediate and the heart will contract. Unfortunately if the lightning strikes the heart at the wrong part of its relaxation the cells will not contract together, rather chaotically. The heart will enter a rhythm called fibrillation. This doesn’t allow it to pump. For that reason the pulse would stop and the heart would be said to be arrested.

If a second strike of lightning or an electric shock occurred at the same point when a heart was fibrillating it would be possible that the heart cells would all contract together in a more ordered fashion. However, there is a problem. The heart could also be struck by lightning and instead of going into this fibrillating chaotic rhythm it could go into no rhythm at all. It could quite simply not beat again. That’s called asystole. It doesn’t end there unfortunately, our poor unfortunate victim also suffers elsewhere. It’s likely that the chest would become relatively stiff and the chest muscles would go into spasm. These muscles take a lot longer to recover than heart muscles so it would be very unlikely that your victim would be able to breathe again. For that reason, although the heart may well restart the victim may well die.

How long would it take to wipe all trace of man from Earth?


How long would it take to wipe all trace of man from Earth?

Thinking first in terms of archaeological timescale if the human race were to become extinct tomorrow then our buildings and roads would gradually decay and possibly within a hundred or hundreds of years many buildings would start to collapse. The sturdier stone built buildings would stand a lot longer than this as we know because we still have Greek Temples and Egyptian pyramids with us today. If we think in terms of those ancient civilisation sit will only be a few millennia before our city would firstly be overcome by vegetation and then would be buried by silt and sediment. If you consider the fabrics used in modern day construction: reinforced concrete, plastics etcetera these would certainly survive the burial for at least as long as the two million year-old stone tools dating from the early humans from Africa, for example. If we think in terms of a geological timescale – this country and indeed most of Europe has been under the sea for a much greater period of geological history than it has been land. The one thing we can be certain of is that sea levels will rise again and this country will be flooded once more by shallow sea and then all of our cities will become deeply buried by marine sediments. Over geological time, over millions of years they’ll be preserved in a rock stratum in just the same way that dinosaurs are preserved in rock strata from 65 million years ago.

When we consider that the oldest fossils we have on Earth are 3 and a half billion year-old single-celled microscopic, soft-bodied bacteria. If such tiny and delicate organisms can survive for that long then certainly the robust skeletons of Homo sapiens can survive for similar timescales. In actual fact organisms that live in the sea are much more likely to be fossilised than organisms like ourselves that live on land. So human fossils will always be rather scarce. We know this already because although hominids have been around for say five million years the actual numbers of fossil human skeletons is very low. Certainly some of us will be fossilised and we will survive buried in rock strata. To answer the question, when the human race does eventually become extinct, as it certainly will, although evidence of our existence will disappear from the Earth’s surface relatively quickly – say within a few millennia – evidence of our existence will survive buried at depth probably for as long as the planet survives.

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.

Would a helium balloon float on the moon?


Would a helium balloon float on the moon?

As far as the balloon’s concerned you need two things to make a balloon float. First you need an atmosphere for it to float in. The second thing you need is gravity. That’s because the reason why a balloon floats is that the balloon itself is less dense than the air around it so gravity pulls on the air around it more than the balloon. The air around it actually tries to push underneath the balloon. That forces the balloon up and makes it float. Unfortunately the moon hasn’t got an atmosphere at all. Therefore you’re missing one of the two things that you need to make a balloon float. In that case a balloon on the moon wouldn’t float at all. It would just land on the floor. However, that doesn’t mean you can’t have balloons or other bodies in space at all. Actually the Russians launched a space mission in the 80s called Vega. That involves putting a balloon in the atmosphere of Venus which is the second-closest planet to the sun. Balloons in space are possible and have been done in the past. Looking to the future there’s a possibility we might be looking at putting balloons on titan which is one of Saturn’s moons. Titan has got an atmosphere and it’s really cold there. There’s obviously gravity there. Therefore you’ve got all the things you might need to have a balloon on Titan. The reason to do that would be to have atmospheric instruments that you would hang from the bottom of the balloon and they would measure Titan’s atmosphere. That’s exactly what we’ve done on Venus with the Vega mission. So unfortunately no balloons on the moon but they do have uses elsewhere in the solar system. Not just on the Earth.

Wednesday, February 3, 2010

Why should we sit far from the TV?


Why should we sit far from the TV?

Televisions really do give off radiation. But having said that, it’s only a little bit of radiation and it’s not that dangerous. What happens is that anything with a cathode ray tube, a tube where you shoot high-energy electrons at some sort of screen, when those electrons hit the screen, they give off very low energy x-ray radiation. This is the same way that x-rays are produced in regular x-ray tubes. So, if you're sitting close to a cathode ray tube, whether a computer monitor, a television screen, a radar set or anything else with that type of technology, you're going to be getting low doses of x-ray radiation.

Now having said that, I’ve got to emphasize, they're low doses of radiation. It’s not enough to be dangerous and in fact, if you watch your television for several hours a day all year, you're getting less radiation than you would from a single medical x-ray and less radiation than you get from the radioactivity that’s just naturally within your body. So, it’s something that we can measure, but it’s not something that’s harmful.

LCD and plasma screens don't give off any radiation at all. They don't use high-energy electrons. It’s a different type of technology. I could not say that they're safer because I don't consider the radiation from cathode ray tubes to be a risk, but I can say that they give off less radiation. As far as sitting too close to the television goes, the further back you are, the lower the radiation dose will be. But having said that, I don't consider the radiation dose even at a distance of just one metre to be dangerous.


Can tress or plants feel? What happens when you chop a branch off?


Can tress or plants feel? What happens when you chop a branch off?

Plants can detect it when you damage them in some way. They are usually more sensitive to things like caterpillars eating them, which will happen in their natural life. For example, an oak tree which is being attacked by caterpillars will respond by producing tannins in its leaves, which makes its leaves bitter. What’s even more interesting is that trees adjacent to the one that’s being attacked can somehow detect some signal and will also start to produce tannins in their leaves, even before caterpillars have been eating. So given that, I think they can almost certainly detect if a branch has been cut off. The problem is that they don’t really have any response to that except to grow another branch.


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.