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.

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.

Why isn’t beetroot dye broken down by digestion?

Why isn’t beetroot dye broken down by digestion?

Well, in some people it is, but in some people it isn’t. The chemical that’s in beetroot that makes them red and makes some people wee red and also pass red faeces, which is what can happen if you eat a lot of beetroot, is a chemical called betacyanin. It’s actually an anti-oxidant that the beetroot makes and it can be used a colour change indicator too, but it doesn’t necessarily breakdown in the intestines of all people.

The things that seem to make it breakdown more are acidity, so if you have very strong stomach acid then it breaks down more. If you have weaker stomach acid, then more can get through into the small intestine, and there, pancreatic juice is alkaline. So that can encourage it to pass through into the colon which is actually where it’s absorbed.

People have done experiments on patients who have had things called ileostomies, which is where you take the ileum, the terminal bowel, and you bring it to the surface of the skin. And you take the contents away into a bag, for example. If you feed these patients with the betacyanins in beetroot they don’t ever get beeturia, in other words, the red dye getting into their urine. That shows that the absorption must take place in the large intestine.

The other things that seem to affect the absorption is a chemical called oxalate, oxalic acid, which you get from rhubarb and rhubarb leaves. That actually gets broken down by bacteria in the small intestine and in the large bowel. So it’s possible that there’s a combined effect whereby some people have a certain genetic makeup that makes them break this stuff down more than others because they have more acidity. It’s also possible that they have certain bacteria living in the intestine that breaks this stuff down more than others, and so that affects whether or not you see it appearing in the bloodstream.

But in people who do get beeturia, what seems to happen is that the pigment comes through the wall of the bowel, doesn’t get broken down, goes around in the bloodstream, and then it gets filtered out by the kidneys and goes into urine, and makes urine go red. But what’s really interesting is that on its way to the kidneys, of course, it has to go through the blood. And I was rooting around on the Internet, and I found this wonderful paper. It was published in the Christmas BMJ 2005 by two doctors, Julia Handysides and Stuart Handysides, who work in Essex... What they did was to - well, they’ve written this paper. I’ll read you this because it’s hilarious.

“One Sunday evening in 2004, our 11-year old son went to bed after various delaying tactics, arguments about friends staying up later, forgetting to brush his teeth, forgetting to come down for a drink of water, and so on. But shortly afterwards, the dining door room opens, and in he comes, cupping a bleeding nose in one hand and gripping the bridge of his nose with the other. We led him to the kitchen sink and helped him to clean up and stem the bleeding, but oddly, the blood on his hands would not wash off. And it also looked brighter than usual. The poor child was interrogated. Is this some kind of ruse or lark to stay up later?

The bleeding stopped, his hands, although stained pink, were now clean and dry. Upstairs, we found crimson stains on the bathroom carpet which proved impossible to shift and remain there over one year later. Our garden’s harvest of beetroot was very good in 2004, and we had eaten some the day before the nosebleed. It dawned on us that on its way to staining urine, the pigment in beetroot might also stain blood as well.”

So that means potentially, all of your internal organs are getting stained bright red by beetroot, and if you bleed, the stuff can come out and stain your skin

Does too much calcium make your bones brittle?

Does too much calcium make your bones brittle?

The answer is, yes it does, surprisingly. Calcium links up with phosphates to make the chemical "apatite" (calcium phosphate), one of the hardest chemicals we know, which is what makes bones hard and stony, and tough.

But if you have too much calcium, that can be as bad as having too little, as in condition osteoporosis where the bones actually begin to lose their calcification and the matrix of the bone, which makes them weak and more likely to break. There’s also another disease called "osteomalacia" where you have too little just of the calcium and that also makes bones weak.

But some people actually lay down too much calcium in bone, a condition called "osteopetrosis" from "petros" as in stony. This is where people can have say, five times the amount of calcium in their bones that they should have. It’s a genetic condition. It’s very rare and I think it also goes by the name "Albers-Schonberg disease" or something like that, but it’s very rare.

In these individuals, the cells that break down bone, called "osteoclasts", don't work properly. This is because the way bone is normally formed involves an equilibrium between laying down new bone and breaking down old bone, and that’s how bones are continuously remodelled.

So if you shift that equilibrium on one direction or the other, you either lose or gain bone. And what scientists have found is that in people who have osteopetrosis, the osteoclasts that normally breakdown bone cannot work properly. They have a deficiency of an enzyme called "carbonic anhydrase" and you need that to break down the calcium phosphate, the apatite, in order to remodel the bone.

As a result, they just keep on making their bones get harder and harder, and harder. Eventually they go beyond the point of this being beneficial and the bones become less flexible and more likely to break, so they get very brittle.

How do mosquitoes lay their eggs? We never see them doing so...

How do mosquitoes lay their eggs? We never see them doing so...

Mosquitoes depend on water for their life cycle. Different mosquitoes live in different environments and as a result they depend on different types of water - stagnant water, big ponds of water, dumped car tyres with a bit of water and so on. You can actually tell which species of mosquito you're dealing with depending upon where they're laying eggs.

The bottom line is the mosquito goes down to the water once it’s mated and different species of mosquito lay eggs in different ways. But they all lay their eggs into water.

Certain species lay them as individual eggs which drift off; others lay big rafts of eggs. The eggs mature and hatch into little larvae, which then have an aquatic phase; they grow in the water and eat algae and things, growing into large mosquito larvae. These then mature into full blown mosquito flies that then take off and come and bite you.

You just have to keep an eye on a patch of water and you’ll see the mosquitoes coming down to lay their eggs!

How are seedless grapes grown?

How are seedless grapes grown?

The correct answer is that the plants that grow them are actually clones. So instead of growing them from seeds, they're grown from cuttings, so from existing plants. So obviously the first seedless grapes were a plant that arose through mutation, that means that they don't have seeds. And some growers must have noticed this. And you can basically take a little shoot or a stem off the plant, dip it in rooting powder, put it in the ground, and a new tree will grow. This is how a lot of plants are cultivated now, and also a lot of seedless varieties. It's causing problems now with bananas though. Because they're all clones, they're getting struck down by funguses and things. If a population is genetically identical, it can very easily be wiped out because it has the same resistance to different pathogens.

Why can you see the moon during the day?

Why can you see the moon during the day?

Why shouldn’t you be able to see the moon during the day? The moon is orbiting around the Earth. It takes the moon about 28 days to go right away around the Earth, come back to where it started. The Earth turns. Obviously, it does a complete evolution in one day, 24 hours, since so you would expect to see the moon go across the sky every day, pretty much. At some point so it might not be visible on some occasions so much but it should be there. So that’s not so unusual

Why does cutting hair make it stronger?

Why does cutting hair make it stronger?

Actually, this is a myth. There is no evidence that cutting hair, shaving, doing anything like that actually makes hair grow more or adjust its strength or its length. Hair goes through three phases and its lifetime. The hair follicle has an anagen phase, when actually grows and makes hair and depending upon what sort of hair, where on the body surface you’re looking, that phase last different lengths of time.

On the head, for example, it lasts for several years, whereas on the face, it might last for weeks and an eyelash, for example, only grows for about three weeks before it goes into the next phase which is called the catagen phase when the hair falls out. And that’s when the hair follicle stops for a while. Obviously, you can imagine if your eyelashes grew for three years that would be a bit disadvantageous because you’ll be looking out through under these curtains, won’t you? So, it’s good that doesn’t happen. Then the third phase is something called the telogen phase, when the follicle rests before it re-starts itself again.

People often say when a person dies, their hair carries on growing after they die. Or, when you cut the hair it comes back far bushier. Both of those things are down to, in the case of someone dying, the skin dries and shrinks a bit around the hair coming out through the skin surface and this makes the hair look artificially a lot longer; and, when you cut hair, instead of having this tapered thin end, it’s got a very abrupt, cut off, sharp end, so the hair looks thicker when it comes back.

So, it’s just sort of illusion; it’s not really any fatter.