The big breaking physics news is the detection of gravitational waves. These waves are distortions in space-time, caused by a large mass doing something spectacular (two colliding black holes in this case) that propagate across the universe and create tiny changes in space when they reach us. The commentary here describes what goes on. Essentially, […]
Continue readingTag: gravity
Plants in circular motion
In our first-year physics lab we have the following horticultural experiment. Here we have some bulbs growing on a rotating turntable. The array of five pots is placed on the turntable so that the centre pot is at the centre of the turntable; the left- and right-hand pots are at the perimeter.The turntable is rotating […]
Continue readingWhen energy conservation doesn’t add up (or does it?)
In the last few weeks holes have been popping up all over Cambridge. They are being dug by 'ditch-witches' – pieces of machinery designed for making small-diameter tunnels for cabling – as part of the installation of fibre-optic cables for the much vaunted ultra-fast broadband. A ditch-witch is about the ultimate in machinery-obsessed-toddler heaven. We've […]
Continue readingHow big is an atom?
I started back at work on Monday thinking that it would be a nice, peaceful day, with no-one else around on campus. Surely, on a beautiful, sunny, 6th January, the entire of Hamilton except for myself would be on the beach at Raglan. Wow, was I mistaken. The campus was buzzing with activity and there […]
Continue readingTorsional pendulums and earthquakes
The shaking here in Hamilton is hardly on the scale of Seddon and Wellington, but it does mean my students aren’t going to get anything meaningful out of their measurement of the gravitational constant this afternoon. The Cavendish experiment uses a sensitive torsional pendulum, whose motion is currently more dominated by ground movement than by […]
Continue readingGravity goes downwards
Yesterday afternoon I was engaged in a spot of DIY – putting up some shelves. Even for me, as someone who takes to DIY like a duck to mountaineering, it’s a fairly simple task, and I’m pleased to say that I got there without the ‘do’ in DIY turning into ‘destroy’. With the help of […]
Continue readingTurning moments
The last couple of weeks has seen a few changes in the house as Benji has finally mastered crawling. Being a rather LARGE baby, he’s been the last of his coffee-group babies to become mobile, but now he’s got it worked out he’s away at high speed. No peaceful sunbathing for the chickens or the […]
Continue readingSandpile physics
Yesterday I had a look around the Tate Modern art gallery in London. As is the way with modern art, there was the expected mix of fabulous, bizarre and seriously-stretching-the-definition-of-art exhibits. One of the pieces on show at present is a pile of porcelain ‘sunflower seeds’, by the artist Ai Weiwei. This piece of artwork is […]
Continue readingPendulum mayhem
One of the main intentions of our 2nd year Experimental Physics paper at the University of Waikato is to have students learn how to put together a physics experiment that measures something, and to measure that thing in a systematic and robust manner. What that means in practice is dealing with uncertainties. Whereas the average […]
Continue readingFundamental Constants and the problem of gravity
A few years ago I wrote, along with a collaborator, a guide to uncertainty analysis (commonly and misleadingly referred to as error analysis) in university physics. Yesterday I had a quick look at this, to see if I should update anything for our new bunch of students. As part of this, I had a look […]
Continue reading