Marcus Wilson

Dr Marcus Wilson is a lecturer in the Engineering Department at Waikato University and author of the Physics Stop blog. His current research involves modelling of the electrical behaviour of the human brain during natural sleep, focussing particularly on the transitions between sleep states. Previous research interests include infra-red physics and signature control (stealth) and quantum Monte Carlo methods. He graduated from Cambridge University in 1992 (BA Hons) and completed his PhD at Bristol University in 1995.

Pass the pigs – ad (almost) infinitum - Physics Stop

Apr 20, 2020

I warn you, this post will make little sense to anyone who doesn’t know the game Pass the Pigs. What do you do on a damp Easter Holiday Monday? (Not that the Holiday Monday bit makes much difference in our house…) Play Pass the Pigs of course. And what do you do when you’re a physicist who’s finished playing Pass the Pigs? You decide to work out the optimum tactics. It’s not just down to luck – the skill is to know when to ‘bank’ your points and when to keep continuing, risking a Pig Out that will lose your points for that go.  To optimise the strategy, you need to know the probabilities of getting the various combinations. Fortunately, there’s a seven-year-old in the house who is learning about percentages and plotting bar graphs and pie charts. So, … Read More

Expanding houses - Physics Stop

Apr 08, 2020

It’s  a beautiful autumn afternoon, we need to get out of the house, and so our bubble sets off on a bike ride around our local neighbourhood, Cambridge Park. The bikes come out of the garage, and, being really certain we have a front door key, close the garage door again. And off we go. A while later, having been up and down and around just about every street in Cambridge Park, having spotted a hundred teddy bears, ten chalk murals on fences, and witnessed (sadly) more than one driveway drinks party (NO!), we arrive back home, dismount our bikes and unlock the door. And try to open it. And try to open it. No… this is not a good time to be shut out of your house…And, after a bit of shoving, finally get it to shift. The … Read More

Eight new COVID-19 cases today. It’s no surprise when you look at some numbers - Physics Stop

Mar 18, 2020

So, as I sit at home with a very, very slight headache (i.e. not at work when I would otherwise be so), the now familiar figure of Ashley Bloomfield reports eight new confirmed cases of COVID-19  including two in Waikato. A surprise, given that we had just twelve yesterday? No. A worry? Maybe, but no more so than it was yesterday. Here are some numbers to make the point. All the cases today are imports – recent arrivals from overseas. Let’s try to estimate the probability of any arrival from overseas carrying the virus. Western Europe has a population of roughly 500 million (depending on which countries you count), and, according to the latest WHO bulletin, have confirmed about 60 thousand or so cases of COVID-19, around half in Italy. That’s roughly speaking about 1 person in eight … Read More

Delays in feedback: Learning to drive, brain waves and COVID-19 - Physics Stop

Mar 11, 2020

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 its borders altogether and eliminating the possibility of re-imported cases, but it will likely look to find the best balance of productivity and risk. Basically, it’s successfully pushed stage 2 of an outbreak back into stage 1,  as Siouxsie Wiles puts it, and will want to keep it that way while still being productive as a country. But changing the way that the outbreak is managed is problematic. The effect of a change in management won’t flow into the figures for several days. When … Read More

A beginning of semester corona-rant - Physics Stop

Mar 04, 2020

I’ve had enough of COVID-19 now. No, I haven’t had it (well, not that I’m aware of), what I mean is I’ve had enough of reading misleading headlines, hearing xenophobic attitudes and dealing with outright selfish behaviour. Let me elaborate: Point 1 We know that every outbreak will be accompanied by a kind of tsunami of information, but also within this information you always have misinformation, rumours, etc. We know that even in the Middle Ages there was this phenomenon. – Sylvie Briand, WHO Health Emergencies Programme. (Quotation sourced from The Lancet, here). And the New Zealand media are no exceptions here. At the weekend I saw headlines along the lines of “COVID-19 more deadly than SARS, MERS” and “I’ve had coronavirus: It’s not that bad“.  What’s wrong with the first? Well, it depends on what you mean by … Read More

Mucky rain - Physics Stop

Feb 20, 2020

While the south of New Zealand has been struggling with too much rain in recent days, here in the north we are so very short of it (though Saturday’s forecast looks promising).  Basically, we have had almost none since Christmas. As someone who relies on rain to wash the car, this means my car is now looking rather mucky. The carwash at the petrol station I use most is not in action any more – I don’t know whether that is to save water or for some other reason – so this means I might actually have to get a bucket or two of water and clean the thing myself, while trying to keep water use to a minimum. (Yes, I know that sounds like a totally selfish perspective and please be assured I don’t actually rate the state … Read More

The numbers are the numbers, except when they’re not. - Physics Stop

Feb 14, 2020

I’m not quite sure of what to make of the new figures for COVID-19 (as we must now call the novel coronavirus – though I’m not sure the capitalisation is correct) from Hubei province: Image from  The spike yesterday is a consequence of a using a different way of defining a case – one based on a clinical diagnosis (i.e. someone has the symptoms) rather than a definitive test. There’s sense in that, but it does make for a mess when one tries to interpret trends in what is going on. Moreover, with only Hubei province using this new method, data from China seems now to be reported using two different standards. This can’t make it easy for researchers into COVID-19. Maybe more worryingly though, from a science perspective, are the reports that two senior Hubei officials were sacked … Read More

The swimming pool paradox - Physics Stop

Jan 24, 2020

It’s another warm day, but the breeze isn’t helping much, so off I go to the inviting outdoor swimming pool (banner picture) at the other end of campus. It’s an unheated pool (well, there’s no artificial heat source), which means one thing: It’s going to feel cold when I get in*. I should just jump in and get on with it, but that’s easier said than done when you know what the temperature is like. Eventually, I get in (brrr!) and have a good swim, by which time I’m not feeling so cold anymore. But I can’t stay in all afternoon. Work to do. So it’s time to get out. And here’s the total injustice of it all. When I get out I feel cold as well. That’s just not fair. It’s cold when I get in, and cold when … Read More

BIG idea physics - Physics Stop

Jan 21, 2020

This morning I’ve been having a quick look through some documentation from The Ministry of Education on proposed changes to NCEA Level 1 Science. For those not familiar with the NZ secondary education system, a typical student would complete NCEA level 1 at the end of year 11.  In this regard, it’s broadly similar to the English GCSE process, though there are plenty of unique features about NCEA. Anyway, NCEA is in the midst of a big review process, and the Ministry of Education is releasing draft documentation on various aspects. One that’s up for discussion is Level 1 Science. There’s been quite some detail put into the documentation (available right here – have a look!). The proposals talk about weaving “Big ideas about Science” with “Big ideas of Science“. The Big Ideas about Science concerns how … Read More

What a difference the decimal point makes - Physics Stop

Jan 13, 2020

I’m back at work following a nearly three-week break over Christmas. We were fortunate to be offered a house to stay in for a week over Christmas, which enabled us to have a holiday in Dunedin and see the extended family reasonably cheaply. But the house came with a catch:  a small, old, cuddly, ball-of-fur that needed daily medication. Amazingly, this kitty was completely compliant when it came to taking her medicine, unlike our own cat of many years ago. We had written instructions from her owners – she was having a gel-like medicine that you rub into the inner surface of her ear. Pre-loaded syringes full of the stuff were supplied – we just needed to put the right amount onto a fingertip (wear gloves or you medicate yourself as well as the kitty-cat), rub it into her … Read More