Thinking about absorbed dose

 

I found a great website explaining radiation dose here. It explains radiation dose in terms of sunburn. So the longer the time, the bigger the dose and the more intense the sunlight, the bigger the dose. I think exposure time is stochastic, certainly for low doses and that in medical terms, you can say that limiting exposure time limits stochastic effects. In the picture above, I am investigating aluminium shielding with a beta source and a Geiger counter. In medical terms, barriers or distance in air reduce the intensity and thus reduce non-stochastic damage.

Another way of thinking about stochastic processes

 

Imagine a dice game where you win a chocolate if you throw a double six. There is a fixed chance of throwing the double six but the more times you throw the dice, the more likely you are to win. However, the prize is the same no matter how many times you have to throw the dice. So the longer the time, the more likely the effect, but the effect is the same regardless of how long it takes.

Thinking about stochastic and non-stochastic

I've been thinking about stochastic and non-stochastic processes in radiation health issues. Stochastic basically means down to chance. In stochastic processes, the effect is independent of the dose received but the bigger the dose, the higher the probability of receiving that effect. I started thinking about driving. Careful drivers are unlikely to have an accident - there is a low probability. But obviously, the more hours you drive, the more likely to have an accident. The insurance companies know this - that's why the higher the mileage, the higher the premium. But driving a higher mileage doesn't make the damage worse in any given crash. That's why I think it is a stochastic process. Now think about reckless driving. If you deliberately drive at higher and higher speeds, then there will be a direct link between the speed and the severity of the accident. This is a non-stochastic effect.
 

Cod liver oil tablet is like the lens in your eye

 I noticed that a cod liver oil tablet was magnifying the weave in the tablecloth. Also notice how it focuses the light behind it.

Mrs B pointed out that you can change the focusing properties by squeezing the tablet so that it acts like the lens in an eye being stretched and squashed by the ciliary muscles.

Pitch drop experiment

 

This tanker reminded me to look up what is said to be the world's longest running continuous experiment. And I was pleased to find that I could watch live! I did think that the liquid diffusion experiment that Lord Kelvin set up Glasgow had been going for longer. I'm sure I saw it on Adam Hart-Davies' Local Heroes.

How far is infinity?

 

The size of infinity is a vexed topic. "An infinite distance" is an important concept in gravitational fields because it is the point of zero gravitational potential. This is because Newton's Law of Gravitation, which is an inverse square law, shows that the force of gravitational attraction is zero at an infinite distance from the Earth. It is then impossible to store gravitational potential energy by doing work against gravitational attraction. So to find the distance to infinity, one way is to hang a mass on a spring balance and travel outwards until the reading says zero. The distance will be finite and will actually be based on the resolution of the spring balance. Hence different spring balances would give different infinities!

Refracting not reflecting on the war in Ukraine

 

We bought The Guardian on Saturday and it came with a poem by Simon Armitage about the war in Ukraine. You can read the article on this link. He talks about a "refracted version of the obscene images". That interested me because people usefully talk about reflecting on events. Both are good physics words. Simon Armitage is one of the best users of the English language. So what could he mean by "refracted"? I guess in the sense that refraction bends light, sometimes leaving images distorted - but then twisted mirrors produce strange reflections. Refraction makes things appear at the wrong depth. Also it helps to focus. The news images have been horrifying and disturbing. It was good to note that so many Physics Nobel Laureates had signed a protest letter in the same newspaper. Read the poem here.