image provider

Radioactivity Simulator


This essay does not describe an existing computer program, just one that should exist. This essay is about a suggested student project in Java programming. This essay gives a rough overview of how it might work. I have no source, object, specifications, file layouts or anything else useful to implementing this project. Everything I have prepared to help you is right here.

This project outline is not like the artificial, tidy little problems you are spoon-fed in school, when all the facts you need are included, nothing extraneous is mentioned, the answer is fully specified, along with hints to nudge you toward a single expected canonical solution. This project is much more like the real world of messy problems where it is up to you to fully the define the end point, or a series of ever more difficult versions of this project and research the information yourself to solve them.

Everything I have to say to help you with this project is written below. I am not prepared to help you implement it; or give you any additional materials. I have too many other projects of my own.

Though I am a programmer by profession, I don’t do people’s homework for them. That just robs them of an education.

You have my full permission to implement this project in any way you please and to keep all the profits from your endeavour.

Please do not email me about this project without reading the disclaimer above.

The goal of this program is to be able to predict what the radiation at any place was at any point in time in the past or in the future. To solve this, you need to bone up on radioactive isotope chemistry. Various radioactive atom isotopes break down at a known rate, irrespective of the molecular chemistry they are involved in. The breakdown products, then often further breakdown, at different rates. You have heard of half-lives and carbon-14 dating. This is the same principle, more broadly applied.

Imagine doing a chemical analysis of a soil sample and finding out the relative concentrations of all known radioactive isotopes. Knowing their half lives you could predict how they will decay and how those decay products will decay. You can then predict the concentrations for any point in the future. You can then calculate the combined rates of the various types of radiation that would be given off per second.

So far, the only real difficulty is collecting the giant list of isotopes and their half lives.

You can add a little complexity, by allowing the introduction of new batches of isotopes from the outside at various points in future, e.g. to simulate the effects of a nuclear war on the other side of the globe, or a serious reactor breach is a nuclear sub in port. You could also simulate the way plants accumulate certain isotopes.

Now the problem gets mathematically more interesting. Can you go back in time and predict what the various isotope concentrations must have been and what the radiation must have been? If you can do this, you might have a way of proving, for example, that there were nuclear explosions in our deep past, indicating either than they can occur naturally, or that perhaps we are not the first civilisation to develop nuclear devices. You could show, perhaps, that mankind or our earlier ancestors must have evolved under much higher (or lower radiation) than now, which would influence the mutation rate and rate of evolution.

It may be that various different pasts could generate the same present. That is for you to discover.

You could tackle this analytically with equations, or with Monte Carlo simulations.

Gurkha, flying a swift and powerful vimana
hurled a single projectile
Charged with all the power of the Universe.
An incandescent column of smoke and flame
As bright as the thousand suns Rose in all its splendour,
a perpendicular explosion with its billowing smoke clouds,
the cloud of smoke rising after its first explosion
formed into expanding round circles like the opening of giant parasols.
It was an unknown weapon, An iron thunderbolt,
A gigantic messenger of death, Which reduced to ashes
The entire race of the Vrishnis and the Andhakas.
The corpses were so burned As to be unrecognizable.
The hair and nails fell out;
Pottery broke without apparent cause,
And the birds turned white.
After a few hours All foodstuffs were infected.
To escape from this fire
The soldiers threw themselves in streams
To wash themselves and their equipment.
~ Ancient verses from the Hindu Mahabharata 6500 BC

This page is posted
on the web at:

Optional Replicator mirror
on local hard disk J:

Please the feedback from other visitors, or your own feedback about the site.
Contact Roedy. Please feel free to link to this page without explicit permission.

Your face IP:[]
You are visitor number