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.

Colour blindness and Bayes’ theorem - Physics Stop

Dec 13, 2018

Following from my last post, there’s more to say about colour blindness in my family. This time we’ll look at my side of the family.  My maternal grandfather was red-green colour blind. That means my mother is a carrier of red-green colour blindness, with a “faulty” (well, “alternative” would be better) X-chromosome.  And as a male, it meant I had a 50:50 chance of being red-green colour blind, as I have only one ‘X’, inherited from Mum. As it turns out, I got the non-alternative version, and so see colours “normally”. But what about my two sisters? They both have one ‘X’ inherited from Mum, and one from Dad. But which of Mum’s X-chromosomes did they get? Since Dad wasn’t red-green colour blind, we know they would have got a normal version from him, and so, if one or … Read More

Colour vision - Physics Stop

Dec 10, 2018

We’ve known for a while that child number 1 (male) is red-green colour blind. This comes as no surprise – with his maternal grandfather being the same. The genes responsible lurk on the X-chromosome. That means his mother is a carrier of red-green colour blindness, and child number 1 had a 50:50 chance of picking up her faulty X-chromosome.  It also means that child number 2 (also male) has a 50:50 chance too, though it’s too early to tell whether he is the same. For the most part, the colour blindness is of negligible consequence. Sometimes it creates some amusement and puzzlement – such as when he asks for the “green one” when there simply isn’t a green one there.  Sometimes it’s intriguing, though.  He clearly sees colours in a different way to me and appears to be able to distinguish … Read More

Hydrophobic cabbage - Physics Stop

Nov 26, 2018

Saturday afternoon saw a break in the rain, and I was able to get out into the garden. The first thing I did was to harvest a red cabbage for dinner. The nice bit of the cabbage is the tightly rolled leaves in the middle, but surrounding that are a whole lot of larger leaves, which I removed and left for the chickens. After another long period of rain, I returned and found the leaves on the lawn filled with water. That wasn’t surprising. However, the water ‘sat’ in the leaves in a rather unusual way. The leaves are very hydrophobic – meaning water doesn’t stick to them. There were no droplets of water on the leaf – they had all run down into a ‘pond’ at the leaf bottom, leaving the edge of the leaf completely dry. The water … Read More

Biological variability and Pakistani batting collapses - Physics Stop

Nov 21, 2018

So, yesterday we had our Science Communication students looking at social media and blogging in particular. Alison Campbell and I talked through what makes a good science blog, and the students got to explore and look for themselves*.  In the coming week, the students need to put up a blog entry themselves. (I’m afraid these will be private to the paper, though we might persuade the authors to release the best of them more widely.) As we talked with the students about blogging, a repeated question was “how do I choose a topic?”  I think the same advice applies to blogging as it does to writing in general: “Write about what you know.”  So, I ask the students what they are majoring in. What topics in their studies have really got them saying “Ooo, that’s interesting”? What do … Read More

Cell phones give you cancer. Yeah, right. - Physics Stop

Nov 15, 2018

It’s been a couple of weeks since the NIH studies on mice, rats and cellphones hit the headlines.  The studies were released with perfect timing to be used in our Science Communication paper – a third-year level paper for science undergraduates on communicating science ideas well. In short, we had half the class look at what mainstream media said about the study (notably this NZ Herald article),  half the class look at what the Science Media Centre released on it, and then, finally, what the original sources for the mouse studies and the rat studies said. I asked the class in small groups to pull out the key messages from the commentary that they were looking at. What we got was: Mainstream media (NZ): Cell phones give you cancer; if you are male then don’t keep a … Read More

The difference between an engineer and a physicist - Physics Stop

Oct 20, 2018

As a researcher who has recently published an article in the elegantly-named journal ‘Biomedical Physics and Engineering Express’ (in other words, biology, medicine, physics, engineering all in one) it’s clear to me that the boundaries that we often like to use to define ourselves are rather blurry. I am a physicist (yes!) but also, at times, I have to drift into being an engineer, biologist, mathematician, computer scientist and so forth. Indeed, many of humanity’s best scientific advances have been made at the fringes of disciplines, where different scientists have come together with different perspectives on the same problem and come up with something wonderful as a consequence. That said, I shall now have a moan about a piece of software (no names mentioned) that has clearly been written by engineers not physicists. You don’t need to understand what my … Read More

Static hair - Physics Stop

Oct 15, 2018

It’s one of those annoying laws of nature that the times you want to do a demonstration of static electricity with a Van der Graaf generator are the times when the atmosphere is least suited to it. Damp conditions equal a damp demonstration. But yesterday was really good. No Van der Graaf generator needed – just a ten-month-old on a trampoline. A bit of crawling around and it really was a bad hair day for the bubba. Apologies for the cropped, slightly out-of-focus cellphone photo. Keeping the subject still was a bit problematic.  The very fine hair will be playing a part in this photo – not much charge is needed to separate out those strands. Needless to say, we both were ‘shocked’ when I lifted him off the trampoline. The post Static hair appeared first on … Read More

Fuel consumption: fewer vehicles means less than fewer emissions - Physics Stop

Oct 11, 2018

So, school holidays are coming to an end.  My son is breathing a big sigh of dismay. And, like so many other commuters, so am I. I’ve enjoyed two weeks of being able to get to and from work (especially the ‘to’) without traffic hold ups and ‘having to go the long way around’.  My 23 km commute from Cambridge to Hamilton goes from about 32 minutes average to about 23. (I hear many of you Aucklanders or Wellingtonians saying …”32 minutes: is that all?…”) The point I want to make is about fuel consumption. My Toyata Yaris is pretty economical as petrol cars go. It’s got a fuel consumption gauge on it – I reset it everytime I fill up and it tells me the average litres per 100 km I’ve done since I last reset it. During school … Read More

New Zealand: It’s time to up our game on disability - Physics Stop

Sep 28, 2018

I read with delight the announcement that the NZ government will now relook at how it funds those who care for family members with disability, and repeal section 4A of the NZ Public Health and Disability Act. That is a big step in the right direction. But it does need to be put into a broader context: when it comes to disability issues, New Zealand is waaaayyyyyyy behind the game. In the last few years I have learned from a disabled friend that NZ legislation on disability is patchy and (like section 4A) discriminatory, not fit for purpose, and, to a great extent, ignored. Individuals, organizations, and even the government alike routinely flout what positive legislation does exist with few sanctions or prosecutions. Societal attitude in New Zealand is that disability is “someone-else’s problem.”  It is not. I will … Read More

Sucking up Spaghetti - Physics Stop

Sep 26, 2018

No. I’m not talking about 6-year-old boys sticking one end in their mouth and sucking.  I’m talking about vacuuming-up old bits of uncooked spaghetti on the kitchen floor. So, on taking the vacuum cleaner over the kitchen floor at the weekend, I could see that there were a few broken strands of uncooked spaghetti to clean up, along with the usual dust and bits of cereal and apple pips and who-knows-what-else? But this is what was puzzling. While the vacuum cleaner had no problem with the dust and bits of cereal and apple pips and who-knows-what-else, it struggled with the spaghetti. It just wouldn’t suck them up, even if I carefully placed the nozzle over the spaghetti. I thought to start with that this was just because the pieces were too long and not getting through the opening of the … Read More