On Christmas Eve, child number 1 spotted a crack in a window. It’s a double-glazed window, and inspection showed that the small, horizontal crack was in the outermost pane. It was perpendicular to the frame, about three-quarters of the way up one side. The origins are a mystery. It MIGHT have something to do with […]
Continue readingTag: waves
Delays in feedback: Learning to drive, brain waves and COVID-19
With the numbers of new COVID-19 cases in China diminishing by the day, China now faces a problem. How to get the country back to work, or partly back to work, or more back to work, without taking too many risks with the virus taking off again. The risk can’t be eliminated, except by shutting […]
Continue readingPhysicsstop back in business
I have been rather conscious of my looonnnnggggg absence from the blogosphere. That really is down to other commitments getting in the way, and then falling out of the habit of blogging. Hopefully this will be a restart. I have a good opportunity here – I have just started a period of study leave (what […]
Continue readingA blatant plug for the NZIP2015 conference
There's no hiding my conflicts of interest here. I'm on the New Zealand Institute of Physics 2015 conference organizing committee. I'm also the NZIP treasurer. And I'm a staff member at the host organization. So, to contribute to the New Zealand physics community's biennial event in Hamilton on 6 – 8 July, click on this […]
Continue readingThe advantage of a transponder
So, as I said, it appears that it's awfully hard to hide a commercial airliner from military radar. But let's backtrack a bit. Why do aircraft carry transponders? (What is a transponder?) There are a couple of reasons here. First, we need to look at a big problem with radar. It has limited range. We […]
Continue readingWhat makes something show on radar?
One of the questions on everyone's lips at the moment is "How does a large passenger jet simply disappear from radar without trace?" It is clearly very distressing for anyone with friends or relatives on board – not knowing what has happened. As I write this, there still seems to be a complete lack of […]
Continue readingHawking radiation in the lab
A highlight of the recent NZ Institute of Physics conference was the Dan Walls medal talk given by Matt Visser. Matt has been working on general relativity. That's not desparately unusual for a physicist, but Matt has been successful in working on some of the crazier aspects of relativity and getting it published – wormholes, […]
Continue readingDispersion in water waves
I’ve been perusing YouTube looking for good videos illustrating wave packets – which are bunches of waves containing different wavelengths. I want to come up with a good illustration for a second year physics paper on introductory quantum theory. This contains a lot of ‘wave’ things. Here’s a nice one I’ve stumbled on. It shows […]
Continue readingMega- and nano-everything
While generally speaking I’m very pleased to hear physics words appear in everyday conversation, I would prefer for them to be used approximately correctly. ‘Exponentially‘ is a case in point – it gets used for something that keeps getting bigger, regardless of how exponential it really is. So, while ‘nanotechnology’ is a good word to […]
Continue readingSeeing circular polarization
Physicsworld magazine is doing a ‘special feature’ this month on animal superheroes – those with rather unusual physical abilities. The best of the lot (in my subjective opinion) is the featured-on-the-cover mantis shrimp. Not because of its ‘dactyl clubs’ that can produce a force of 700 N, but because of its eyesight. The mantis shrimp […]
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