Corona Moon

 

The full Moon was setting, viewed through high cloud, giving an optical corona like those seen through steamed-up glasses in these mask-wearing days. I could only make out the outer red and yellow bands. The water droplets are mich further from my eyes than when they are on my glasses. I don't know if that makes a difference. It is also likely to be different due to different droplet size. 

mgw in Grizedale

 

Coming up from Patterdale towards the Hole-in-the-Wall path, we found this sign. Now I know that it means that lorries heavier than 7.5 tonnes cannot cross, but I realised that I didn't know what mgw stands for. We guessed right with "maximum gross weight". Usual Physics teacher rant about tonnes measuring mass and thus the word "weight" being incorrectly used. Gross here means the total of everything - the vehicle and the load.

Neon in a sodium street lamp

 

It finally occurred to me to ask "why do sodium street lamps start out red before they warm up to orange?" Turns out that the tube is filled with a mainly neon gas mixture which lights up immediately and glows red before the sodium is fully vaporised. This article is brilliant. There's a lot more there to think about.

Big Crush not the Big Crunch at Green Side

 We visited one of the two huge craters on Green Side next to Sheffield Pike. It turns out that they are not quarries but are the result of a massive underground collapse in 1862. W T Shaw's Mining in the Lake Counties implies that it was due to miners taking lead out of two parallel vertical veins that left a plug of rock suspended. It duly collapsed one Sunday, so no one was hurt. https://en.wikipedia.org/wiki/Greenside_Mine has more details and an excellent photograph. The event was called the Big Crush. I spent the day thinking it was the Big Crunch. When I started teaching, it was expected that there was enough mass in the Universe to make slow and eventually reverse the expansion of the Big Bang, resulting in the Big Crunch . The 1999 evidence from Type 1a supernovae shows that the Universe is undergoing accelerated expansion so the Big Crunch is not going to happen.

Another 2 metres

 

This was in Ambleside a couple of months ago. If resolution = +-half scale division at each end, then total uncertainty in the social distance = +-1sheep.

Lost in Math by Sabine Hossenfelder

 

I read the book above. The central thesis is that experiments cost so much to build and take so many years to construct, that most ideas will not be able to hope for experimental verification. So what do we do then? Also, how do we choose which ideas to test when the funds are available? Sabine Hossenfelder suggests that what has happened is a retreat into mathematical aesthetics. Does the theory look simple and elegant? If so, it must be true. I think she's right to point out that the real world might not have to be simple and elegant. 

Red sky in the morning

 

I was brought up on caravanning holidays with the weather-predicting rhyme "Red sky at night; shepherd's delight. Red sky in the morning; shepherd's warning". I was amazed when I started teaching that none of my classes knew it. This morning the eastern sky was red. It is very stormy now. I understood that it works because frontal systems pass from west to east and take several hours to pass. I looked this morning and did a double take, because surely the clouds lit up red are those in the east. Recourse to this suggests it is because the air in the east is the stiller air that has more scattering dust trapped but that stormier air is coming from the west. This needs pursuing. However I was amazed to find that I had never noticed Jesus quoting the saying in Matthew Chapter 16. This means that the saying is at least 2000 years old and it still works.