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Ten things 'Invisible Worlds' has taught me
1. The human eye is not all it’s cracked up to be.
Human vision is pretty miraculous, but our eyes aren’t quite as powerful as you might imagine. What we can see is stuff that reflects or emits light with wavelengths in a very narrow band (since you ask, from about 750 to 400 nanometres). What we can’t see is the rest. That’s all matter that reflects or emits light over the other 99.99999999999% percent of the spectrum. In fact, we’re almost blind.
2. If I was a honeybee, my garden would look like a psychedelic acid flashback…
Honeybees are one of a few rare beasts who can see in ultra-violet. This was news to me, but not to the flowers in my back garden who exploit this fact ruthlessly by advertising their presence to the bees with all sorts of inventive patterns in order to lure them in for pollination. Completely invisible to us but not I’ve now learnt, to the bees…
3. When something’s on fire, it isn’t. Well, not exactly.
Watching something burn, it’s easy to think the flames are actually on the thing that’s burning, eating away at it. That’s what it looks like. But it’s not that simple. In the invisible infra-red spectrum we can see that what’s actually happening is the heat is causing the object to give off combustible gases, and as they escape it’s those combustible gases in contact with the oxygen in the air that cause the fire. So the flames are not on the thing that’s burning, they’re in the air around it.
4. Continued incontinence can be very dangerous to your health… if you’re a field vole.
Voles piddle continuously as they go about their business. Not a very nice notion but apparently rather useful, as it tells them relevant ‘vole’ things like who’s been on their patch of grass, what sex they were and what direction they went off in (though sadly not how cute they were). But, those handy pee trails also reflect ultraviolet light and one of our vole’s main enemies is the kestrel, which – sadly for Mr Vole - can see in ultraviolet. So all it has to do is follow the pee trail all the way to the dinner table.
5. The humble common cold is actually the source of a masterful feat of engineering… the sneeze.
You know how we all cringe when someone sneezes anywhere near us? ‘Stay at home!’ we think, ‘don’t come near me with your nasty infectious nose…’ Well – I’m afraid it’s even worse than you might have realised. That sneeze shoots out of that nose at up to 100 miles an hour, contains around 40,000 separate droplets of horridness and can travel vast distances through the air. And the worst bit is – the drops you can see (and so avoid) make up just 4% of the total volume. So that leaves… well quite a lot of invisible snot…
6. Geckos have the worst case of split ends in nature, but it’s the secret of their success.
On ‘Invisible Worlds’ it took a small stunt team and half a day’s rigging to get me to walk up a vertical wall. But geckos can scamper up them without a second thought, and then cling from the ceiling with a single toe. The secret of their superhero powers lies in the invisible hairs that cover each toe. Each of these is ten times thinner than a human hair and there are millions on each toe. But look a bit closer, around 40,000 times magnification, and you can begin to make out the split ends on those hairs. It turns out that at the nanoscale each of them branches off into hundreds of further tiny hairs of their own. It’s these split ends that hold the key to gecko’s amazing grip.
7. You can find the fastest thing on earth……living in a cow pat.
The fastest thing on earth isn’t Ussain Bolt, it isn’t a cheetah, it isn’t even a Ferrari. It’s a fungal spore. Cow pats are home to hundreds of them, and courtesy of a new generation of ultra high speed cameras, capable of taking over 250,000 images per second, we can now actually see those spores in action. One moment they’re stationary, and then one millionth of a second later they’re travelling at 25metres a second, sustaining a force equivalent to 180,000g. Astronauts on the space shuttle have to cope with just 4g. Anything past 5g and we start blacking out. So why do they go to such trouble? Well, it’s all about survival. In order to reproduce, they need to get themselves as far away from the dung as possible – so they can get eaten again.
8. I mustn’t put my finger in a tank containing a pistol shrimp
Pistol shrimps are less than an inch long, but with an oversized claw, shaped like a boxing glove, they’re not to be messed with. In real time it looks like they see off opponents such as crabs by simply jabbing at them. But use high-speed cameras and you can tell something far stranger is going on. They win their fights without ever landing a punch. All their damage is done at a distance, as their closing claws force a jet of water to spurt out at close to 70 miles per hour, creating a low pressure ‘bubble’ in its wake. When this collapses, massive light, heat and energy are briefly created. Inside the bubble it momentarily reaches temperatures as hot as the surface of the sun, soaring to more than 4,000C. It’s this invisible force that causes much of the damage.
So the knockout punch comes from the bubble, not the claw.
9. If you’re worried about cellulite, don’t swim in the presence of a high speed camera.
Dolphins are the perfect shape for swimming. Slowed down 40 times their torpedo-shaped smooth bodies just scythe through it. There’s little drag, the water is simply displaced and the dolphins appears to be gliding, cruising along at 20mph. In contrast, in water it’s not just our shape that limits our speed, it’s also our skin itself. If you can face seeing the full effect drag has on the human body, you need to film a swimmer with a state of the art high speed camera that can offer thousands of images a second at HD resolution. Then you begin to see the way water actually buffets the skin and distorts its surface. Even the fittest swimmer is transformed. And it really puts orange peel thighs into perspective.
10. My phobia of spiders is serious.
In 20 years I’ve done some frightening things for tv. I’ve stood on the summit of the world’s tallest road bridge, I’ve climbed to the top of the Sydney Opera House, I’ve abseiled off a bunch of buildings, I’ve driven at 300mph (you might remember that) …Top Gear even kindly arranged for me to be in a car that then got struck by 800,000 volts…and I’ve gone along with everything…absolutely everything, without fuss, without hesitation. But when Invisible Worlds asked me to milk a spider I totally bottled it.
World of Wonder
This series is part of World of Wonder - a year of Science across the BBC in 2010. From popular science to Chaos Theory, there's a little something for everyone.Find out more about World of Wonder on BBC Science
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