Why get goosebumps at all? We get cold, or stressed, or frightened, or hear a cool guitar riff, or see some inspiring art, and bang, we get these odd bumps.

When other mammals with long hair all over their bodies get cold, frightened, angry, or sexy, then their hair stands up. If they’re cold, the fluffed hair traps air and helps with insulating their body. If they’re fighting, erect hair can make them look big and nasty.

We all have body hair, regardless of our attempts at waxing, shaving, using lasers, and other forms of depilation and epilation. A long way back on our family tree our distant ancestors had long body hair, and we have retained this (vestigial) ability to make our hair erect. Near the base of every hair on your skin there is a tiny muscle, beautifully called the arrector pili. When it contracts, the hair stands up. When it does this, the surrounding skin bulges, forming the ‘goosebump.’

And because we now have short body hair (well, most of us) we notice the bump more than we notice the erect hair.

But what sets the arrector pili off?

It’s due to the release of the most famous of our hormones: adrenaline. It’s release from the adrenal glands into the body at various times:

When we’re cold. (squirt)

When we’re stressed. (squirt)

When we’re excited. (squirt)

When our mother-in-law is coming up the driveway. (squirtsquirtsquirt!)

We have two adrenal glands, which are small blobs that sit like squishy beanies on top of our kidneys.

In fact, this is where the name adrenaline is derived: the Latin ad, meaning ‘on’, and renes, for ‘kidney.’ Adrenaline is also known as epinephrine, which is the Greek words epi, meaning ‘on,’ and nephros, for ‘kidney.’

(Incidentally, if you know someone with bad allergies, they may have a shot of adrenaline ready in an EpiPen. And, yes, that’s ‘Epi’ short for ‘epinephrine’, but Greek-word pedants may call it an ‘on top of the pen.’  You know who you are…)

We get an outside stimulus, adrenal glands squish adrenaline into our bodies, and our hairs stand up. Goosebumps!

I remember when Monkey Island 2 came out, I would start and restart the game over and over so I could listen to the opening theme music. It made me tingle. And then, about a week later, the effect disappeared. Thinking about it today, I can only imagine my body became used to the stimulus. Humming the song incessantly meant my mind was no longer ‘surprised’ by the music. No more adrenaline.

So if you want the goosebumps to last, restrict your exposure to the causing stimulus: that song, that picture, that girl. Exposed too much, and the tingles may disappear, and you might wheel about like an addict, looking for another source…


This Rough Science came from a question from @annaryanpunch: why does music/something we read/an artwork give us physical goosebumps? Her blog, four hundred years ago a baby went to sleep, features poems written from suggestions by Twitter people. Ask her nicely and she might write a poem for you!

Hero’s Engine

Picture a brass sphere, about the size of your head. Make two holes, one at the north and south poles. Insert two brass straws into these holes and weld into place. Now bend the straws at right angles, but make sure they are pointing in opposite directions. Fill the sphere with water and put it onto a rotisserie over a roaring fire.

The water boils, and turns to steam. It shoots out the brass straws, pushing the sphere around on the rotisserie. Faster and faster it goes, until it (literally) runs out of steam.

You’ve made a Hero’s Engine, named after its inventor Hero of Alexandria in the first century AD. He called it an aeolipyle, a combination of the Greek word “Aeolus”, the god of winds, and the Latin word “pyla”, meaning ball. (So aeolipyle could be translated as “Ball of the Wind God”. *ahem*)

You might see Hero’s Engine mentioned in popular science coffee table books if you look up an entry on “steam engine.” Before going onto discuss Newcomen and Watt and Carnot at the beginning of the Industrial Revolution, the article might have a small paragraph saying “Did you know the steam engine was actually invented in Greece two thousand years ago?” And you’re invited to muse of how the world would look if the Industrial Revolution happened a millennium and a half earlier.

In my opinion, the steam engines that kick-started the Industrial Revolution bear as much resemblance to Hero’s Engine as a Cadbury chocolate factory does to Willy Wonka’s. Yes, they both produce chocolate. But if you actually wanted to make chocolate, you would probably want to follow the Cadbury model rather than try and work out the cost/benefits of using a slave race of Oompa Loompas, the practicalities of using a waterfall to mix chocolate, and the sanity of a big, scary tunnel.

Hero’s Engine is nothing more than an elaborate toy. It uses jets of steam to move, and is not really capable of much else other than spinning furiously. Whereas the engines that came about through the insights of Newcomen, et al., used the expansions and contractions of steam to work pistons that provided useful mechanical work, and also lead to the establishing of the Laws of Thermodynamics, a major milestone in the history of science.


This Rough Science has come about because @pinknantucket asked about the Hero’s Engine demonstration in an show about air and weather.

The demo uses a bottle that you fill with liquid nitrogen. A lid goes on the bottle that has two tubes bent in two different directions, and the bottle goes into a cup of water. As the nitrogen changes from a liquid to a gas, it forces its way out of the tubes, spinning the bottle in the cup of water. Brilliant!

Koch’s Snowflake

One of my favourite geometric phenomena that I crowbar into an all-purpose analogy uses the idea of “bounded infinity.”

It’s a version of Zeno’s Paradox, though is more rooted in pen-and-paper geometry.

Take a circle, and drawn an equilateral triangle, with each of its three vertices touching the circle’s perimeter.

Next, split each edge of the triangle into three equal lines.  Use the middles lines as the beginning edge for three more equilateral triangles.

Do the same operation of these new triangles, drawing more triangles.

And repeat.  Repeat until the pen’s nib is too fat to accurately draw the triangles.

Now start again, this time with a bigger piece of paper.

Now write a computer program that will generate the triangles for you.  Keep the computer running until the heat-death of the universe.

In theory, you could have an infinite number of triangles, and they will never cross the boundary of the circle.

The diagram is called a Koch Snowflake, after Helge von Koch, a Swedish Mathematician who was particularly interested in number theory, but also annoyed the family by drawing triangles on everything.

I usually pull out this analogy when discussing rules or boundaries place on a project or presentation, and how there can still be an infinite amount of creativity and variety within the borders.

For instance, last year I participated in a Pecha Kucha night, where presentations were only allowed 20 slides with 20 seconds per slide.  It was interesting at first to hear trained presenters rail against the format, but the limitations still allowed for a huge amount of flexibility.  It was a brilliant night.

Alan Moore also used the snowflake in his (and Eddie Campbell’s) Jack the Ripper graphic novel “From Hell.” If you don’t want to trawl through that tome, at very least skip to the appendix where he write a very interesting comic essay about Ripperologists, and within the boundary of Whitechapel and the facts of the Ripper case, there is a huge variety in theories and stories and solutions.  And we will never know the truth.