Where Grey Matter meets Dark Matter

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Episode 16 - 28 July 2009

Chris and his wacky dinosaur burrow story is at the start of the show.


  • The news story.
  • And the real stuff: MARTIN A. J. 2009. Dinosaur burrows in the Otway Group (Albian) of Victoria, Australia, and their relation to Cretaceous polar environments. Cretaceous Research 30, 1-15.


"That's one small step for man, one giant leap for mankind."*

Neil Armstrong saying the words. A nice staticy version - the way it should be.

We've all heard the words and we recognise them as awesome. Of course, Neil Armstrong didn't just wake up one morning and decide to ride a moonbeam to work - he only got there using the combined efforts of stacks and heaps of people. The Chinese are generally credited with developing the first rockets, but it wasn't until Robert Goddard filled his rocket with dangerous liquids and set them on fire, that rocketry really took off (who can get tired of these puns?). Liquid fuels gassify much more readily than solids and so they are much more explosive, which is exactly what you want in a rocket. But they also blow up more easily.

The Russian Konstantin Tsiolkovsky contributed an equation to the mixing chamber, which tells you the most important when building a rocket - how much fuel you need. Hermann Oberth possibly had an even greater effect on the space race - he was the teacher of Werner von Braun, the man responsible for the Saturn V rocket that launched the Apollo missions (and also for Hitler's V2 rocket). The Americans picked him up right at the end of the war, before the Russians did.

Of course, the Soviets had their own cluster of rocket scientists, however, like much of the Soviet brass, they concentrated more on internal politics than astronomical trips. But that didn't stop them taking the early lead in the Space Race. With Sputnik and then Yuri Gagarin being the first person in space, the Americans needed to pull their finger out. And with the help of JFK, that's just what they did.

US president John F. Kennedy's speech about going to the moon. Rice University, September 12, 1962.

It wasn't long before the solar winds of change started to blow westwards, and it became apparent that the Americans were making giant leaps towards the moon. In fact, it was right at the end of JFK's 8 (+/- epsilon) year deadline that Armstrong, Aldrin, and Collins got there.

The Russians had a covert moon program, but with more pressing needs like a starving population and over-populated gulags, money was tight. But worse, the in-fighting between the designers of the various components ICBM'd the whole thing. Their rocket was the N1. They launched four of them, and four of them blew up.

A short vid about the Soviet N1 rocket, the launch on the 3rd of July, 1969.

And (according to Babelfish) if Neil Armstrong had to okay his phrase with a Portuguese man, who tells a Frenchman, who tells an Englishman (after he puts his beer down) then he would have said "That is a small stage for the man, a giant traction for the humanity." Stirring.

*To those people who complain about the lack of an 'a', we pity you. It sounds better this way. To those of you who don't know what the hell we're talking about: you're alright by us.


We've talked about the Fallout games before: essentially it's what would have happened if massive nuclear war had occurred in the future with a 1950's mentality (think of the Cadillac Cyclone with a nuclear fusion - hmmm, cool and environmentally responsible).

The Cadillac Cyclone. If cars could fly, they would all look like this.
And wouldn't that be a better world? Source: Serious wheels

Real nuclear fallout (yes, the game was named after something in the real world) is the rubbish that is thrown into the air when a nuclear bomb goes off. It contains leftover nuclear fuel, nuclear fission products and innocent bystanding particles made radioactive by the enormous levels of radiation.

Fallout after a bomb blast. Source: KI4U

This stuff then 'falls out' of the sky over the next few hours, days, weeks and even years.

So how exactly does this stuff get made? Well I'm glad you asked. There are two types of nuclear reaction: fusion and fission.

  • Fission is where you split an atom. This is where you bombard the nucleus of an atom with neutrons that break it apart. You really want to use atoms with a morbidly obese nucleus, since they only need a little push to fall apart. When it happens, the remaining chunks fly away from each other really fast. This makes a big explosion, but the real problem is that these left over chunks are unstable and highly radioactive. That means they give off dangerous radiation for a long time after the reaction.

    Here a neutron has landed on Uranium-235 nucleus. For a short time it becomes
    an unstable uranium-236 nucleus before exploding into barium, krypton and 3 neutrons.
    These neutrons can go off and find new uranium to blow up. Source: Wikipedia

  • Fusion is the opposite of fission - you take some atoms and stick them together. You would use hydrogen for this (in one of its isotopic forms) just like the sun does, and the output is a helium nucleus. That and incredible amounts of energy, and nasty neutrons - these are the things that do all the damage. The neutrons are particularly worrying, because they can irradiate other elements and make them radioactive. But the fallout risk is not so bad - except that on earth, fusion gets going at REALLY high temperatures (a million degrees or so), so a fission reaction is used to get it going.

Deuterium and tritium (both isotopes of hydrogen) fuse to create
helium, a neutron, and a hell of a lot of energy. Source: Wikipedia.

It's the left over fission particles and the irradiated bits of dirt that are flung up high into the atmosphere, before falling back down that makes fallout.

The fallout is dangerous stuff because it's radioactive, meaning that it gives off invisible radiation: gamma rays, neutrons, electrons and alpha particles. And because it is so small (down to a few nanometres) it gets into everything: houses, clothes, hair, food, water... It is especially bad if eaten or breathed in, since then the radiation gets right into your body.

The reason for this is that the most damaging radiation (alpha particles, which are the same as a helium nucleus), is also the weakest. A piece of paper can be an effective shield against them, but if they are in your blood, or your thyroid gland or your brain, then there's no pieces of paper in there to prevent DNA damage and cancer. Not good.

But as time goes on, the problem starts to go away. Each of these radioactive things has a half-life, after which half of it has disappeared. It does this all by itself. So the longer the stuff is up in the atmosphere before it comes down, the less fallout there will be. This is why some people say it is better to use bigger bombs than smaller ones, since the bigger ones might leave the stuff up there for longer.

Here's a graph showing estimates of how high the top and bottom
of the nuclear cloud goes depending on the size of the bomb. Source: Wikipedia.

So after the bombs have dropped: stay inside, and keep the windows closed. If you do have to go outside, then keep it short, and don't bring those clothes back inside. Wash thoroughly. And you should probably get a crew cut.


  • The New Scientist article that simulates a nuclear detonation in the US capital.
  • The Star (1950), The facts about the atom bomb: From Hiroshima to Hydrogen, London.
  • Office of Civil Defense (1961), Fallout protection: What to know and do about nuclear attack
  • Here's some people doing research on radiation exposure in Japan, the only country to have suffered a nuclear attack
  • New Scientist talks about some treatments for radiation exposure. It must be a brand of RadAway.
  • A paper on the issue with an uplifting title: Robock A., Oman L. & Stenchikov G. L. 2007. Nuclear winter revisited with a modern climate model and current nuclear arsenals: Still catastrophic consequences. Journal of Geophysical Research-Atmospheres 112.
  • Sue Rabbitt Roff, Project Sunshine and the Slippery Slope
  • Some more information about Project Sunshine was found on page 29 of The Nuclear Borderlands by Joseph Masco. Preview here.

Mistakes we shouldn't have made but did anyway:

  • Anthony said that JFK's speech about going to the moon was in 1961. Actually, it was September 12, 1962.
  • The atomic number of uranium is 92. It is the 3rd heaviest naturally occurring element. The heavier ones are neptunium (93) and plutonium (94).


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