Thursday 9th December 10

A milder day weather-wise, so it was cold but not bitter.  This meant that I was able to go and do some work in the garden, loading sacks of compostables onto two heaps, and building two logpiles.... a dry one outside the front door and on each return trip, freshly chopped 'green' logs, heavy with sap, to be taken down the garden to sit quietly for a year or two in a tidy pile.

The space between our house and the semi next door, our shared driveway, had become extremely icy and slippy, so I spent a bit of time with the spade, breaking chunks of compressed snow off the concrete and making a less slippery path to walk along.  I worry about Gill falling and injuring herself; she doesn't need snow and ice to do that, so the slippery conditions make it a lot more likely.

I also did a bit of work inside, washing up and hoovering, and keeping the stove going (just the one today), and soon after 6pm, Melody came round to deliver her 12 year old genius of a son to me, and I took my own genius son plus Melody's on the bus down to Cafe Scientifique at City Screen to go to a talk about Dark Matter.

This talk was extremely difficult for me to understand.  The presenter was Tom Whytnie, a PhD student at Imperial College, London, and part of the High Energy Physics Group.  He explained that scientists think that the visible and measurable matter and energy in the Universe is about 4% of the total, and the remaining is 70% Dark Energy, and 26% Dark Matter.  This has been hypothesized by looking at how disc galaxies revolve, and our understanding of gravity.

Tom works at the Compact Muon Solenoid at CERN, the Large Hadron Collider, which smashes protons together at almost the speed of light.  The debris from these collisions might give hints as to what Dark Matter is... but it is unlikely that it will ever be seen, as it is 'dark' and invisible.  Whether it exists has to be inferred from what goes into the collision and what comes out.... and if there is stuff missing, that might be Dark Matter.

However, if these experiments don't come up with some results, it might be that our understanding of gravity is incorrect, and a lot of science will have to be rewritten.  I now understand quite a bit more about this subject area than I did, but my son got his head around it far more easily than me, and at the end of the talk, he asked the first question, which was a really good one, and showed he'd taken in a lot of the ideas.  I felt very proud of him.

The talk overran a bit, and finished at 9.30, the time Gill was expecting us home.   On the way out I spotted the tethered balloons floating above the Mansion House.... nice one James Alexander, not a litterbug!   We went to get the number 6 bus and didn't have to wait that long.  We got back home just after 10pm, and Melody soon set off home with her lad, and we got ours up to bed pretty quickly.