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Why can't elephants dance?


It may not be a question you've ever asked yourself before, but the Royal Institution of Great Britain has the answer.

Ever wonder why you've never seen an elephant quickstep across African plains or do the tango in Thailand? Well, it's just one subject addressed in this year's Royal Institution Christmas Lectures.

A fixture at the venerable research institute since 1825, this year's lectures investigate, among other things, why size matters in animal behaviour.

Especially for the Magazine, this year's lecturer Dr Mark Miodownik, a physicist at King's College London, answers some questions you may never have thought of asking - but will want to know the answers once you do.

Why can't elephants dance?

Although they are one of the biggest and most charismatic animals on Earth, elephants would not last long on Strictly Come Dancing.

While the African elephant - the largest living land animal - defies its size by running at speeds of up to 25mph, its legs are so heavy they cannot change direction fast, which means the animal is not so good at more graceful or intricate moves.

It also means they cannot jump, which rules out the pirouette.

image captionNo parachute needed

The size of an animal determines its chances of surviving a fall from an aeroplane or a tall building.

Smaller animals hit the ground with a force proportionally lower than their weight.

That is why falling out of an aeroplane is fatal for humans, but hamsters live and spiders don't even feel the impact.

An ant is yet to win an Olympic medal, but they are an incredibly strong animal compared to their size.

The strongest ant can lift up to 100 times its own body weight. That would be the equivalent of a human lifting around the weight of an African elephant. An Olympic weightlifter can just about lift double his or her own weight.

This is because ants are so light they only use a small amount of their muscles to hold themselves up, leaving the rest of their strength for lifting. So, as things get bigger they get proportionally weaker.

Based on the properties of gecko hands, which contain tiny hairs that enable the animal to walk up walls, scientists have created an artificial tape called gecko tape. This tape mimics the millions and millions of hairs on a gecko's hands.

These hairs enable its hands to have a huge effective area in contact with the wall and create tiny van der Waals forces which attract the surfaces together. These forces are enough to make it stick.

It leaves no residue and can be turned on or off by the gecko. Gloves that stick to glass are already in development. In theory, this could allow humans to walk up walls, but also could allow astronauts to cling on to things efficiently in space.

Imagine electronics that could fix themselves - no more calls out to electricians or taking in your prized gadgets back to the shop.

Building a self-fixing television sounds like the stuff of science fiction, but materials that have the ability to self-assemble - or self-heal - have already been found.

For example, epoxy compounds can heal surfaces if they get cut - in just the same way that a scab forms if skin gets cut. So, in years to come, it is not so preposterous that your TV could fix itself after breaking down.

Roald Dahl has already sent an elevator to space in his story Charlie and The Great Glass Elevator, but to make this a reality a tower of 36,000km high would have to be built.

image captionThe moon please

To do that you would need a material that is strong but really light. At the moment, materials like concrete, steel and aluminium wouldn't even get close because they are too heavy and the force of gravity pressing on them would eventually make them collapse. Even with carbon fibre - the strongest and lightest material used at the moment - a tower only about 9km high could be built.

But a new kind of carbon has recently been discovered that is extremely strong and light and is made from carbon-nanotubes, which are tubes of carbon just one atom thick. Scientist have now started to join together these nanotubes which could make a super strong cable that is able to transport an elevator to 36,000km and then off to space.