In March I’ll be giving a physics careers talk at a Surrey school (Nonesuch School for Girls). I haven’t given a careers talk for ages, I used to do a fair few when I was admissions tutor but I stepped down from that job years ago. So I thought I would see what our graduates actually go on to do, to refresh my memory.
As a scientist I know that correlation does not imply causation. Just because two things, A and B, are correlated does not imply that A causes B or vice versa. For example, there is a correlation between the number of pirates on the world’s oceans, and global temperature, but this does not imply that pirates, or their absence, is causing global warming. But even if there is cause and effect going on, then you still have to work out if A causes B, or if B causes A.
In the biological physics course I am teaching, I talked a lot about the fact that on lengths greater than around a tenth of millimetre, diffusion of molecules is too slow to supply the needs of living organisms. To get round this they had to evolve pumps, propellers and cargo transport infrastructures. The time to diffuse a distances increases as the square of the distance travelled and so diffusion is slow on all lengths large enough to be visible to the human eye.
One of the nice things about WordPress is that it shows the countries people are in when they read this blog. The result for about 7 months of this blog is below. Somewhat to my surprise, Brazil is in 4th place. Hello nice people from Brazil! At the other end of the spectrum, in 7 months only a single post has been viewed from Tunisia. Hope I haven’t offended my one Tunisian reader.
On Sunday I went to the National Gallery‘s Making Colour exhibition. It was fascinating. One of the first paintings you see is Sassoferrato‘s Virgin Mary – shown to the left. It was painted over 350 years ago, but the blue cloak is still stunning. The exhibition was basically on how artists achieved beautiful colours like that of the cloak.
I have just got back from co-organising a science workshop in Lausanne, Switzerland. It was great fun, I thoroughly enjoyed many of the talks. And as an organiser it made me happy to see the scientists enjoying the talks then realising that they can use these ideas in their own work. Some of the attendees who met at the meeting for the first time were even talking of teaming up and working together. If they do, it’ll put a smile on my face that I have helped that.
I study nucleation, but mainly via modelling on a computer. The guy below, Harley Morenstein, took a more personal approach. Incidentally, if you are bored of the Vine looping just click on it.
Drinks like Diet Coke, lemonade etc, are carbonated, i.e., have carbon dioxide pumped into them under pressure to make them fizzy. If you carefully take the top off and are gentle with then (as opposed to giving them a shake) most of the carbon dioxide remains in the drink. This means that the amount of carbon dioxide dissolved in the water is actually above the solubility of carbon dioxide in water (at atmospheric pressure), and so this carbon dioxide wants out (technically speaking it is thermodynamically ‘downhill’ for the carbon dioxide to leave the water and go into the atmosphere).
The carbon dioxide comes out as bubbles and if the drink is not shaken these bubbles can find it hard to start to form. This initial step when a tiny bubble starts to form is called nucleation. If nucleation is not possible then this traps the carbon dioxide in the Diet Coke or whatever the drink is.
Until something comes along to make nucleation easier, like Mentos. Mentos are an American sweet, and for reasons nobody really understands, carbon dioxide bubbles nucleate like crazy on the surface of Mentos. So when the guy in the Mentos suit drops into the Diet Coke tub, bubbles of carbon dioxide nucleate like crazy, and you saw the result above.
Naively, you might think then when presented with a statement that is new to us, we start out not believing it, and then decide if we believe it or not. But apparently, it is the other way around. We have an inbuilt tendency to believe everything we are told, and only then afterwards do we check to see if it is true.
Three hundred years ago, an act of parliament created a prize for the solving a then highly pressing technological problem: How a ship at see could work out where on Earth it actually was, in particular what its longitude was. If you are like me and always get longitude and latitude mixed up, longitude is position east-west, while latitude is north-south. As I learnt last week in a IoP South Central general talk by Dr Rebekah Higgitt, the biggest (of several) contributions to solving this was by John Harrison, who made the first clocks that were very accurate at sea.