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The definitive host: March 2013

The definitive host

de·fin·i·tive host (duh-fin'eh-tiv) n. 1) An organism where a parasite undergoes the adult and sexual stages of its reproductive cycle 2) Someone you go to for interesting stories and/or facts, and puts on one hell of a dinner party 3) This blog, devoted to science and other geeky subjects

Saturday, March 30, 2013

Here be dragons!

On Sunday March 31, 2013, the epic series Game of Thrones returns to HBO, with a rabid fan base already behind it. Full disclosure – I am a huge fan of the show and books in which they are based, and the show is probably one of the best on television, in my opinion.

The show takes place in Westeros, an Earth-like analogue with a wide array of people living, loving, fighting and killing to achieve what everyone wants – power. Some want it, while others are afraid to lose it and others are content just to stir the pot and see what happens. The show is equal parts political drama, medieval period piece and fantasy. In fact, the fantasy part is fairly muted at the beginning, but only increases in occurrence after one notable event at the end of the first season/book.

**Beware, very mild spoilers ahead for season and book one of Game of Thrones**

The event in question involves one of the most prevalent fantasy creatures – dragons.

In Westeros, dragons have been dead for hundreds of years, along with the magic that accompanied them. However, once the dragons come back, magic awakens as well.

But, that is in a fantasy world – what about on Earth (or an Earth-like planet)? Could dragons exist?

According to Professor John R. Hutchinson of The Royal Veterinary College in London, UK, the discussion all comes down to size and gravity. When a land animal increases in mass, gravity quickly dominates all its activities because of the various pressures it exerts on the animal’s body (but an animal in water is a very different story, just compare an elephant - the largest animal on land - with a blue whale, the largest animal in the ocean).

Now imagine an animal the size of a dragon – one long-dead in Game of Thrones was described as possessing jaws so big that it could swallow a mammoth whole and eclipse whole towns with its shadow. For much an animal to exist, it would need large bones to support its weight and muscles to move it, not to mention huge stores of energy to move and support such a large creature.

“Inevitably, the range of extreme activities that animals can do decreases as they get larger,” says Hutchinson. “So elephants don’t jump or gallop, whereas mice do; and large flying birds don’t whiz around like hummingbirds.”

One of the most identifying characteristics of a dragon is its ability to fly, but the problem of size rears its ugly head once again. As flying animals get bigger, their wing size needs to increase just as much, if not more.

“[A dragon] would need immense wings to support its weight,” said Hutchinson. “A lot of weight is wasted in that heavy tail and hind legs as well as the bulky head, too — those don’t help the dragon fly well at all. So at best such a smallish dragon would be a clumsy flier, and would have a hard time taking off.”

“If we move to a 500, let alone a 5,000 kilogram dragon, flight basically becomes out of the question in Earth’s gravity. So, one needs to invoke magic to explain a flying dragon.”

Therefore, in a world without magic, it looks like a dragon of any size would not be able to grow to such mythic proportions as described in various fantasy stories. But, what about if dragons were built like birds?

The largest bird found today is the California condor, with an average weight of 10 kilograms, a length of just over 4 feet and a wingspan of over 10 feet having been recorded (which is two and a half times its length!).

Conservatively, let us say that a dragon weighs 50 kg, and if it follows the same construction and weight distribution as a condor, than it would clock in at just over 20 feet in length and a wingspan over 50 feet.

Large? Sure. But theoretically possible.

But bigger dragons, like those described in Game of Thrones would be more like 500 kg, which would make their length 200 feet (or about two-thirds of a football field) with a wingspan of 500 feet (or the height of a 50-storey building!)

Suffice to say, even if it could exist, the physics alone would not allow such an animal to move, much less have enough energy to fly.

While dragons would not be able to fly or reach such massive size described across the globe, what about the other impressive characteristic of a dragon – its ability to spew fire?

According to Hutchinson, dragon fans will be disappointed once again.

While some animals, such as bombardier beetles, can excrete a hazardous and incendiary-type of fluid from their bodies on rare occasions for defense, fire-breathing it is not.

“Intensely hot flame takes massive amounts of energy to produce and to be hot enough to damage flesh, it would thus cook the dragon from the inside out anyway,” he adds. “I don’t see a realistic way that a very large animal could breathe some sort of fire-like substance. Tiny animals might get away with something like that on a small scale with chemical cocktails, but a huge animal would neither be able to fuel the energy needed to breathe fire nor avoid scorching itself. Again, magic (or a good imagination) is the only option to allow for such a creature.”

With fire-breathing going up in a puff of smoke along with monstrous size and ability to fly, what are we left with to satiate our need for dragons?

Komodo dragons and Pterosaurs.

Komodo dragons are the largest living reptile on the planet, growing up to 10 feet and 150 kilograms, able to run up to 20 kilometres per hour and dive up to 15 feet. While not able to breathe fire, Komodo dragons do have a bad bite, filled with dangerous bacteria and venom – which they use to incapacitate and even kill prey with a single bite.

Pterosaurs, on the other hand, were flying dinosaurs existing millions of years ago. Hutchinson says that they could weigh 50 to 250 kilograms, have wingspans up to 36 feet and when standing, could be up to 18 feet (thanks to Brian Switek, paleontological guru for help with those numbers). Sadly, as with all dinosaurs, they have long since gone from this world.

“We have had large sort-of-dragon-like animals in the past in the form of pterosaurs or even sort-of-giant eagles and vultures, but a real dragon in the sense of classic or modern fantasy just ain’t going to ever happen.”

Sadly, science tells us that dragons are merely a fantasy, but it doesn’t stop millions of people loving them. Just because dragons are an impossible flight of fancy on Earth, in the land of Westeros, anything is possible.

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Saturday, March 9, 2013

Short and sweet

Every since Science Online 2013 ended, I have been very busy with a variety of things including work, developing some super-secret side-projects and more. But being busy is often a double-edged sword.

While these projects are developing and turning into some fantastic stuff that I am sure you all will enjoy - it has left me with little time to read the ever-increasing amount of books I endlessly accumulate and post on this blog.

But, take heed loyal reader, as I have not forsaken you.

Over the past week and a half, I've been communicating with experts in various fields, and asking them questions that can come up in normal conversation - for example: How can black holes exist if we cannot see them? Or, how hot is magma locked in the Earth's core?

The process is simple - I ask an expert in a field four questions. They pick two and answer each in four sentences of less so that anyone can understand.

I hope to continue this series going, so if you have any ideas for experts or questions to ask, please do so in the comments!

Man, that's heavy
The first expert is David Shiffman, a shark conservationist and ecologist graduate student in Florida. He blogs regularly at Southern Fried Science and tweets at @WhySharksMatter.

Question 1: Since it is right there in your Twitter handle, I must ask - Why do shark matter?

Answer: Many species of sharks are top predators in their food chains. Top predators can influence their ecosystem both by regulating populations of prey, and by influencing the behavior of prey. In short, they help keep ocean ecosystems healthy.

Question 2: How can whales grow so big in the water, but the biggest animal on land (the elephant) is only a fraction of that?

Answer: The answer to this is simple- gravity. There's a limit to how big things can get on land because after a certain point they get too heavy. Water provides increased buoyancy. Blue whales are bigger than the biggest land dinosaurs ever were.

Short, stocky and strong

This leads perfectly into our next expert, Brian Switek, a freelance science writer who spends his life getting to know anything and everything he can about dinosaurs. He blogs at National Geographic and is on Twitter as @Laelaps.

Question 1: Who would win in an arm wrestle, an average man or a T. rex?

Answer: There would be no question. Tyrannosaurus rex would win. Estimates based on bio-mechanics indicate that the arm of T. rex was about three and a half times more powerful than that of the average person. The arms of T. rex were short and stocky, but very powerful.

Question 2: How did mammals survive the extinction event 65 million years ago and the dinosaurs didn't?

Answer: Actually, dinosaurs did survive. Avian dinosaurs - birds - escaped extinction and carry on the dinosaur legacy today. And even though mammals also survived, many mammal lineages died out in the catastrophe. Exactly why birds, mammals, and other creatures persisted while the non-avian dinosaurs died out, however, is a mystery that hinges on how climate change, volcanic activity, and asteroid impact translated into pressures that changed the world.

Invisible doesn't mean it's not there

The final expert is Matthew R. Francis, a physicist and science writer who writes at Bowler Hat Science and tweets at @DrMRFrancis.

Question 1: How do we know black holes exist if we cannot see them?

Answer: We can't see black holes directly, but many of them are surrounded by matter - mostly gas stripped off stars or from other sources. When that gas falls toward the black hole, it forms a fast-rotating disk, that heats up and emits a lot of light in the form of X-rays and radio waves. So, even though black holes don't emit any light of their own, they can be some of the brightest objects in the Universe.

Question 2: What does E=mc^2 actually mean in terms of everyday life?

Answer: "E= mc^2" literally tells us that mass is a form of energy, and anything with mass will have that energy even if it's not moving. Most of the mass of your body is in the protons and neutrons in its atoms, but those are made up of the smaller particles known as quarks. The mass of a proton is a lot greater than the mass of the quarks that make it up; the rest of the mass comes from the energy that binds the quarks together. In other words, "E=mc^2" is responsible for most of the mass of your body!

Thank you very much to Brian, Matthew and David for all their help, time and effort - and remember, if you have any ideas for experts or questions to ask, please let me know in the comments.

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