Radiation Part 2: The Radiation Spotter’s Guide

Radiation comes in a variety of flavours.

For the sake of simplicity, let’s focus on three that come from radioactive decay: alpha particles, beta particles, and gamma rays.

Imagine our pellet of radioactive material. As we looked at in Part 1, the atoms making up this material will lose a small amount of their mass as a bullet of radiation that shoots into the wide world . The type of radiation the pellet emits depends on the unstable material making up the pellet.

If our pellet of material is undergoing alpha decay, then its atoms will be losing its mass in the form of alpha particles. These are the underachievers of the radiation family (though have an insidious dark side that we’ll see later; a bit like Scar from the Lion King.) You are easily shielded from them by a sheet of paper. Actually, even thick air or ever your skin is enough to stop these particle pushovers.

Beta decay creates beta particles, which have a higher energy and higher speed, and can happily pass through you like fermented prunes. That said, beta particles will be stopped by a material with a sufficiently high density, such are a sheet of aluminium.

A material undergoing gamma decay is really nasty. Its mass decays into gamma rays that easily penetrates skin, aluminium sheeting, concrete, One Nation supporters, and will only be stopped by a material that is sufficiently dense; say, a chunk of lead.

As the observers of this pellet of radioactive material, we are concerned about which type of radiation is being emitted. All three have the potential of doing damage to the cells in our body, but if it is weak like alpha particles, then the chances of it travelling the distance to us let alone penetrating our body’s cells is small. Beta particles have a higher risk, but the radiation to beware of is gamma rays, smashing through your body like a very small but high-speed bullet.


Carrying on with our accident at our hypothetical nuclear powerplant, the next questions we and any Walkley-winning journalist should ask:

o If the plant is leaking radioactive material, what sort of radiation is it emitting?

Knowing what sort of radiation is being emitted, then we can make an estimate of how dangerous it is to be exposed to it. And this is the subject of Part 3.

Radiation Part 1: What is Radiation?

When the media pronounces the word “radiation,” it is spoken in a terrifying font, conjuring images of poisonous muck oozing out from a powerstation, a monsterous tenticular nightmare sprouting from polypous perversions that will crawl about the countryside, reaching deep into your living cells to do something really naughty.

But what is radiation?

To understand radiation, we need to make a distinction between two terms: “radiation” and “radioactive material”.

Radioactive material emits radiation; the radiation zooms away from it in (more or less) a straight line in all directions until it encounters something it can’t penetrate. Imagine the material being a lightbulb, and the radiation is the light it emits.

Radiation can be a highly energetic particle, and it can be a wave. Radiowaves are a form of radiation. So is light. Some radiation is harmless to us. Others can alter us and our environment.

Imagine a pellet of radioactive material is sitting on the ground in front of you. It might be glowing because it is emitting radiation (not necessarily green like it does in the movies).

Now zoom down to the atoms of the material. Choose any atom and watch it. At some point that atom will shoot off some of its mass as a unit of radiation. We can’t predict when this happens. (The fact that you’re looking at the atom waiting for it to happen makes the process even trickier, which is a story in itself, and involves cats in boxes.) Nevertheless, when it does happen, the atom that is left has less mass, and will have different properties: ergo, it is now a different material.

What happens to the mass the atom loses? It become a unit of radiation, and takes off into the world like a students on a gap-year until it bumps into something or eats something it regrets in Kuala Lumpur.

Zoom back out and look at the pellet on the ground. Over time, the pellet of radioactive material changes as its atoms lose mass. The pellet will eventually change (perhaps through a range of materials) into something that is stable and no longer emitting radiation. Remember, it is impossible to predict when an atom will change, so you can’t predict when the entire pellet is completely stable. It is much easier to accurately predict when a fraction of the pellet has changed, so the life of radioactive materials are measure in the time it take for half of the material to change. Hence, “half-life.”

Depending on the material, its half-life be a few seconds, or it could as much as millions of years, or anywhere in between.

Whether the radiation is dangerous or harmless to us depends on the unstable material. Types of radiation and its effect on humans is the subject of Part 2.


There are two questions that should arise in your head, and the heads of any journalists, when an accident happens at a nuclear facility:

o Is the facility emitting radiation?

o Is the facility leaking radioactive material?

Two important and different questions. If the answer to the first one is ‘yes’, then it is an issue if you are standing in the facility, but not if you are sitting in a city several hundred kilometres away, even if the prevailing winds are in your direction. Imagine the radiation like light coming from a lightbulb: is it going to be brightest up close or several hundred kilometres away?

If the answer to the second question is ‘yes’, then there is a different set of concerns and more questions to ask. Why type of radioactive material has leaked? What is the size of the material? If we stretch the light bulb analogy, imagine clouds of light bulbs, different sizes, drifting on the wind, settling over the countryside. All of these lightbulbs could be emitting light…

For now, if you are journalist about to start an article on Fukushima, ask yourself if the term you are looking is “radiation” or “radioactive material.” The distinction is important.

We don’t use the Richter Scale

Well, kind of, sort of, no.

It’s some common parlance to talk about earthquakes being “something point sometime on the Richter scale.”  But these days that is likely to be wrong.

The Richter Scale was invented by Charles Richter with the help of Beno Gutenberg in 1935.  Richter was looking for a way to quantify earthquakes; attributing a number to an earthquake which could tell you about the amount of seismic energy released by an earthquake.

Before an earthquake goes off, huge amounts of potential energy is built up in the earth’s crust: for instance, as two tectonic plates move against each other.  There comes a point when the crust can no longer hold the stress it is undergoing, and rocks crack and deform as the two plates give way.  This seismic energy radiates outwards as waves through the surrounding land, moving the ground beneath our feet.

(Experiment: Get two chocolate chip biscuits.  Pretend they are tectonic plates and push them against each other until explode in your hands.  Biscuit quake!  Don’t worry about the mess: if you sing like Carole King at the same time, people will forgive you.)

Richter’s scale was intended to measure this energy and report it as a single number, much the same way the “apparent magnitude” scale used in astronomy to measure the brightness of stars and other objects in the night sky.

However, the scale was developed using a particular instrument for measuring quakes:  the “Wood-Anderson torsion seismometer”, (future Rough Science article.)  The way the scale is calculated means that it is dependant on the instrument it was recorded on.  The value also become unreliable for earthquakes larger than 7.

These days the Richter Scale is only used for small, local earthquakes.  For earthquakes such as the recent Sendai earthquake, or the earthquake that triggered the 2004 Boxing Day tsunami, they are measure in the “Moment Magnitude” scale (MMS).  This scale also measures the size of earthquakes in terms of energy released, but is not dependant on the instrument it is measured on.

When you hear about earthquakes in the media, it is more likely they are measured on the MMS: for instance the Sendai earthquake was a magnitude 8.9 quake.  If someone tells you it was 8.9 “on the Richter scale”, tactfully correct them.

On the other hand, the MMS breaks down for small local quake, where the Richter Scale is still used.


I first started untangling the MMS from the Richter Scale when the 2004 Boxing Day tsunami happened.

There were some news articles saying it was 9.1 on the Richter Scale.  But then other articles mentioned this “Magnitude Moment Scale” thingy.

I was writing an information sheet about the earthquake and tsunami for the venue I was working at, and decided to investigate these two scales.  Wikipedia was still in its infancy, and the page on MMS was next the useless, having just a handful of equations.

So I called the geology department at a major university.  I ended up speaking to a lecturer, who kindly told me he was a bit under the pump at the moment, and that if I leave an email he’ll put me in touch with one of his postgraduate students.

The postgraduate student was prompt in replying.  That afternoon I got an email from him, which contained a single link to the Wikipedia page on MMS.

This Rough Science article is dedicated to that postgrad student, where ever he may be.

(Guest art by Gabriel Elliott, a drawing of a boat in a tsunami after watching a video of a Japanese town being destroyed in less than six minutes.)

Saturn’s Ears

A little over four hundred years ago, in the Grand Duchy of Tuscany in Italy, a man named Galileo Galilei was given a new toy that had become popular in the Netherlands. It was a wooden tube with some ground-glass lenses at either end, and had the cool property of seeing things far away as if they were nearby.

Galileo started pointing it at all sorts of things. What made him different from the casual observer was that he meticulously documented and repeated his observations, then published his results for anyone else to read and make their own observations.

(At the time you would have called him a “Natural Philosopher” as the word “Scientist” wasn’t coined until the nineteenth century.)

You have to remember that the generally accepted view of the cosmos for people living around him was that the Sun and all the planets went around the Earth. Not only was this common sense, but it was also what Aristotle (who lived two thousand years before) had said. And Aristotle was, you know, a genius.

The observations made by Galileo were new. The planets and the Moon appeared to be spheres.  Venus went through phases much like the Moon.  Jupiter appeared to have smaller planets going around it. And then Saturn…

Saturn was just weird.

Imagine you are looking through Galileo’s wooden tube with glass accessories pointed at Saturn. The hand ground-lenses magnify the image, but they’re not perfect. You’re looking through Earth’s atmosphere, distorting the light from Saturn through layers of air expanding and contracting as it heats and cools. Every servant footfall nearby rattles the image, until Galileo tells them to leave the wine jug and bugger off.

And what do you see?

It appears to be a shimmering circle. Out of either side are…what?

Seeing objects around Jupiter was big surprise. But what to make of these projections from Saturn. Mountains? Small planets very close to Saturn’s surface?

These handle-like projections had Galileo stumped. In a letter to his favourite pupil, Benedetto Castelli, he wrote “…the ball in the middle was seen quite distinctly and was surrounded by two dark spots positioned in the middle of the junctions of the mitres, or, that is to say, ears.”

Forty-five years after Galileo’s initial observations, another Natural Philosopher living in the Netherlands, Christiaan Huygens, using larger telescopes with more accurately ground lenses, identified the objects as rings around Saturn.


I first came across “Saturn’s Ears” many years ago in a funky show about the solar system. It was only a handful of lines, and went something like: “Galileo thought Saturn’s rings were ears! He should get his eyes checked!”

The line felt like a cheap shot. It invited the audience to think how smart they were to silly old Galileo. I suppose I was feeling the same feelings as Douglas Adams when he heard someone making a joke about indestructible black boxes, and how they should actually make planes out of the same stuff. A joke from ignorance.

It was a throw-away line, and jeered at Galileo’s work that, despite everything working against him, was still able change our view of the universe.

(Thanks to @annaryanpunch who found the Galileo quote, from http://tinyurl.com/4f6lhyk)

Why does the wind blow?

Pucker your lips and blow. That is air moving on a very small scale. Outside, wind is air moving on a very large scale. Great volumes of air!

How do you get a great volume of air to move?

Air makes up the atmosphere; the sphere that remains when you removed the Earth. It’s a thick shell of gas that goes right around the Earth, and extends from the ground up to the edge of space.

Because it’s made of air, it expands when it gets hot, contracts when it cools down. If a large volume of atmosphere is heated by the sun, it will swell. If air over the sea cools down, as it contracts there will be room for air nearby to move in. All of this air movement we feel as wind.


That’s a rough explanation. Atmosphere and weather is a very complex system. I haven’t mentioned the different layers of the atmosphere, and how the Earth’s rotation also effects air movements. But hopefully that’s enough for @sorrell_smith, who asked the question on behalf of her daughter.

One of the coolest experiments to see air expanding and contracting uses boiling water, cool water, a bottle and a balloon. (Usually at this point people say they’ve seen this one before, but I would wager your haven’t seen this version before.)

Fill the bottle to the rim with boiling water. Wait half a minute, and tip the boiling water out. Trap the now hot air inside the bottle by putting a balloon over the bottle’s neck. Now drop the balloon in the cool water.

As the air inside the bottle gets cold, it contracts. There’s now room inside the bottle for outside air to move in. But there’s a balloon in the way. The balloon, THUNK, gets pushed inside the bottle.

My question to you is: how do you get the balloon back out of the bottle?


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.