Ada Lovelace and the Konigsberg Bridge problem

The Weston Library had a display about Ada Lovelace. She is regarded as the first computer programmer. She was a friend of Charles Babbage who designer the first calculating machine and she is credited with writing the first algorithm for a machine like that.

I was interested to see the Konigsberg Bridge problem mentioned. I remember hearing about it when I was at school. Essentially it is a question of whether you can cross seven bridges once in a single journey as they were laid out in the town of Konigsberg. https://en.wikipedia.org/wiki/Seven_Bridges_of_K%C3%B6nigsberg You can read about how Leonard Euler proved it was impossible. It brings up the mathematical concept of "graphing" -  ie drawing networks. I have posted about this before when dealing with knots.

Embroidered referencing in the New Bodleian

What was the New Bodleian has been turned into the Weston Library with exhibition space and a cafe.To mark the 800th anniversary of the Magna Carta, someone decided to embroider the whole Wikipedia page on the subject. It's huge. What I love about Wikipedia is the way that it is well-referenced. I have been trying to teach my classes to include (date accessed) when referencing web pages. This is important because unlike printed material, they can change.

Is the reflected light still quantised?

I was going to post about low energy bulbs giving out quantised light rather than a full black body spectrum like a filament bulb. The reason is because high energy electrons are fired through a gas in the bulb. The electrons hit the gas atoms. This provides energy to knock different electrons that are bound within the atoms. The bound electrons jump up energy levels and then de-excite, emitting photons of light but only at the frequencies permitted by the electron level jumps. So you get a spectrum with discrete frequencies. I took this photograph with a diffraction grating to illustrate this point. But looking at it, the coloured part is the light from the lampshade - reflected light. It is from a white surface so it is likely to be the same as the bulb, but might it not tend back towards a full spectrum? Need to think about this.

Stripy clouds over Wigton

 I spotted this stripy sky over Wigton this morning - the sort of cloud formation that made me do a lot thinking in the summer. Then I remembered an experiment from the old Nuffield Physics A Level course. Stick a knife blade high up under the narrow flow from a tap and you get a stripy pattern too.

For the tap, it is a stationary wave. At least that's what the book says. For a stationary wave, an incident wave hits an obstacle and bounces back. The incident and reflected waves interfere. Not quite sure where the wave is originally because it's just a column of water. Anyway, it occurred to me that with the clouds, one moving air mass could be hitting another more stationary air mass to replicate the knife scenario...?

"Bad Greenhouse"

A colleague pointed out this website to me: http://www.ems.psu.edu/~fraser/Bad/BadGreenhouse.html I'm interested in getting to the bottom of this. I was taught (back in the days when the next Ice Age was being predicted so before any idea of a runaway Greenhouse Effect) that a greenhouse works because light from the Sun at short wavelengths can get through the glass. These are absorbed and heat the contents. The contents are now warm but not as warm as the Sun, so they now emit at longer infra-red wavelengths which can't get through the glass. I had heard rumours that there might be problems with this. The linked webpage talks about the glass stopping convection. That's undeniably true. I'm really interested in the idea that the atmosphere radiates electromagnetic waves like a star. I've never heard that said before but it's utterly logical. For any black body (the name given in Physics to a perfect emitter of electromagnetic waves (remember that matt black painted objects cool faster..) Wien's Law applies: wavelength of peak emission intensity x absolute Temperature = a constant. So the colder the object is, the longer the wavelength, from my original teaching. But the idea that this could heat the Earth's surface more than the Sun is new to me and may be worthy of some calculations... Hopefully more to follow.

Looking back in Wigton car park

The inside rear view mirror is a plane mirror. It shouldn't distort the object. Theory says that the virtual image (the picture in the mirror) should be the same distance behind the mirror as the object is in front. In other words, it should show true distances. The driver's door mirror is convex. This gives a wider field of view but the image appears further away.

Starlings in ultra-violet

Here's a Starling on Mrs B's garden feeders. Male and female Starlings look identical to me. So how do they decide who is a girl and who is a boy? It turns out that the female Starlings have patches of ultra-violet on their heads. You need to think of ultra-violet as a different - just one that we can't see. It's counter-intuitive - a colour that you can't even imagine. But Starling eyes can see those frequencies. I wonder what it looks like? When we "see" ultraviolet or infrared, they are done as FALSE COLOUR images. Get it explained properly by watching this awesome programme soon whilst it is still on the iplayer http://www.bbc.co.uk/iplayer/episode/b06pm7t8/colour-the-spectrum-of-science-3-beyond-the-rainbow