Proving the Earth is round again

Someone commented to me earlier this week about atmospheric scientists who had posted detection of the shockwave of the Hunga Tonga volcanic eruption in barometric pressure readings from weather stations. They suggested this would be a good opportunity to do a new article for 100 Proofs that the Earth is a Globe.

At first I thought it would take too much time, a resource I have little of these days with all my teaching commitments and trying to squeeze in making comics. But then I began to see more posts on Facebook and Twitter about the event, and they built up a compelling picture. The best thing was a video that a scientist had made showing the shockwave converging on the opposite side of the world. When I saw that I knew I had to write the article.

So yesterday I started work on it. But I really wanted to use that video, and so I wrote an email to the scientist and asked him for permission. And this morning he’d answered to say yes, so it was all systems go. So, here’s the article.

My wife and I went out for pizza tonight to our favourite pizza place. And tonight is virtual board games night with my friends.

New content today:

Parallax and gardening

The plan for today was to write a new proof for 100 Proofs that the Earth is a Globe. I managed to get one completed: 45: Parallax of the Moon. This proof includes a practical experiment that I can do, with the help of readers in different places around the world. So if you’d like to help, please give it a look!

After finishing that, I walked up to the hardware store to get some hex keys. I have a hand towel holder in the bathroom that’s been loose for ages. It’s held onto a wall bracket by a grub screw with a hex key head. In the past few days I searched for the original hex key, but couldn’t find it in the likely places, such as either the mini toolbox under the kitchen sink, or the big toolbox in the garage. So I had to go buy some hex keys. Measuring the size of the needed hex key was pretty much impossible, so I figured I’d just buy a set with various sizes.

Of course I got to the hardware stores and they have sets in both metric and imperial sizes, and of course I have no idea which one I need, so I end up having to buy both. Fortunately it was only $5 for a set of 8 keys in each type, so I paid $10 for 16 keys. I got home and picked a likely looking size – 2.5 mm from the metric set – and it fit perfectly. I tightened the grub screw… but the towel holder was still wobbly. So I unscrewed it completely and took it off the bracket, and discovered that the bracket itself was loose on the wall. So I got a screwdriver and tightened that up, then reattached the hook and tightened up the grub screw, et voilà! The hook is now firmly attached and not wobbly any more.

And I have 16 new hex keys, 15 of which I’ll probably never use. And one of which I might never use again.

This afternoon I went out to the park across the street to use my new weeding tool (bought the other day) to remove some bindii from the grass. I’ve never done weeding in a garden/lawn before, but it was pretty easy to figure it out. I used gardening gloves, but even so, the thorns from the bindii sometimes poked through the gloves and into my fingers. It was some work squatting on the grass and pulling weeds, but I collected half a bucket full in about an hour, clearing an area of a few square metres of bindii. This will make it much more comfortable for Scully to walk around, although I’ll need to clear quite a bit more space to get the little park fully clear.

Tonight is our fortnightly games night, still virtual because of COVID. I’ve managed to win a game of 7 Wonders and 6 Nimmt so far.

New content today:

Audio Proofs that the Earth is a Globe

Today I uploaded a bit of a project I’ve been working on. A week or so ago I was talking to my mother and I told her about my 100 Proofs that the Earth is a Globe project. She’s moderately interested in sciencey stuff and said it sounded fascinating. The problem is, her eyesight is deteriorating badly and she can no longer read. She used to be an avid reader, but has been forced to switch to audio books.

So I said I could record myself reading the articles, and send her audio files. I started with an introduction, and then launched into the first few proofs. She loves them! So I’m going to keep recording more. And today I uploaded what I have so far and linked the audio files from the Proofs index page. So far I have the Introduction and the first 6 proofs recorded. I’ll be adding more over time.

Today I also did the weekly grocery shopping, a day earlier than usual, because I had a plan for dinner and I needed an ingredient, so I decided not to make a separate trip to the supermarket. The plan was to cook cacio e pepe pasta, and I needed some Pecorino Romano cheese. I had a bit of trouble finding it, since there was none in the cheese cabinet where the fancy imported cheeses are. But I found some in the regular cheese section where the bog standard sliced cheddar and stuff was, so that was good.

I grated some of the Pecorino with some Parmigiano Reggiano, and then ground about a teaspoon of black pepper. I cooked the pasta, and also cut some asparagus into small lengths and microwaved it briefly to add a bit of vegetable into the dish. When the pasta was cooked, I mixed it all together, and – the unusual touch – added a splash of lemon juice. Just enough to give it a hint of lemon tang. It turned out really good! And my wife loved it too. I’ll definitely be cooking this again – especially as I have 2/3 of the Pecorino left.

New content today:

Human rights in ethics

This morning I had my second Ethics class since resuming last week. I was planning to use name tags for the kids again, since I haven’t quite learnt all their names yet, but I discovered that I didn’t have enough left for all the class. Rather than give some of them tags and some not, I decided to just not use them and see how I went. I went around the class and marked the roll, managing to name most of the kids correctly, and I paid attention to the ones I couldn’t to try and remember them for next week.

When I arrived before the class, there were a few teachers sitting in my classroom. Normally they have a staff meeting on Wednesday morning, in the staffroom. But today they were doing it in a socially distanced manner, with a few teachers spread out in some classrooms, talking via Zoom or some such conferencing system. While this is good, it meant I couldn’t get into the room to set up the chairs for my class until the bell rang and the teachers left. So it was a bit of a rush getting set up and started.

We continued talking about animal rights from last week, although today the focus was on human rights, as a comparison. We discussed whether people should have rights to food and shelter, being able to go out without fear of being attacked, education, to socialise with friends, and other things. We brought it back to animals with the question of whether people have a right to be able to swim in the ocean safely, versus whether sharks have a right to live without being killed by people. This sets up the conflict between human and animals rights that we’ll be discussing next week. The kids were better behaved today and we had a good discussion, so that was really good.

This afternoon I dedicated to writing a new Proof the Earth is a Globe. I’m almost finished, but it will take a bit more work tomorrow to polish it off and post it.

New content today:

Games and Proof

Tonight is fortnightly games night. I’ve just finished my first game of the evening, a 6-player game of 7 Wonders. Normally I don’t do very well in games against my friends, but I won this one, so that’s a good start to the evening!

Today I finished writing the new Proof that the Earth is a Globe that I started yesterday, and posted it. So that was a good job completed.

New content today:


Today I started working on a new one of my “100 Proofs that the Earth is a Globe“. It’s the first one I’ve started for some time, because I’ve been distracted at home a lot with my wife working from home and haven’t been able to sit down knowing that I could work uninterrupted for several hours at a time. But today I just knuckled down and got started despite that. Normally I’d finish an article the same day I start, but I’m only about half way through, so hopefully I’ll be able to finish and post it tomorrow.

I took a break at lunch time to go do another 5k run. My fastest time for the 5k last year was 29:06, and last week I managed 29:16, so today my goal was to break 29 minutes. Unfortunately I miscounted laps and after sprinting the last couple of hundred metres and bending over exhausted to catch my breath while I checked my time on my phone, I discovered that I’d only covered 4.6 km! I still had a lap to go! I had to put the disappointment aside immediately and get the legs working again and set off on another lap…

But I managed it! My time for the full 5k today was 28:05. While running the last few laps I felt pretty exhausted and again really had to push through it mentally to avoid stopping, but now a few hours later my legs definitely don’t feel nearly as tired as last week.

I boasted to my friends on our online chat. One asked me if I was running laps of a street route, but I said no, the streets here are much too hilly for me to run, so I do laps of the nearby sports oval. And then this conversation happened:

Friend: Actually your run is consistent with orbiting a very dense object at the centre of the oval. #100ProofsGoreHillOvalIsABlackHole

Me: hmm…. I could calculate the mass, given the radius and speed… Damn, now I have to do it.

And I did. Approximating the oval as a circle and using the equation for a circular orbit: v = √(GM/r) gives the mass M of an object needed to cause me to orbit it at speed v and radius r. My speed was 5000/(28×60+5) = 2.97 m/s. I ran 11 full laps, totalling 5.14 km, so the radius of the oval is approximately (5140 m)/(11 laps)/(2π) = 74.4 m. Plugging the numbers in gives M = 9.81×1012 kg. Which is basically 1013 kg to any sensible degree of accuracy.

According to Wikipedia, 1013 kg is almost exactly the mass of comet 67P/Churyumov–Gerasimenko. Which is a little large to fit inside the oval. But never fear, for it’s also roughly the mass of two teaspoonfuls of degenerate neutron matter, which one could easily fit into the middle of a sports oval. If that much degenerate neutron matter had been in the middle of the oval, I could have stayed in orbit about it by running in a straight line. Although I suspect my orbit would decay rapidly after 5 km of running…

Friend: I’m so happy I nerdsniped you into doing this.

And just to include a photo: for dinner tonight I made a vegetable quiche, stuffed with potato, cauliflower, pumpkin, broccolini, onion, cherry tomatoes, eggs, and cheese:

Vegetable quiche

New content today:

Lightning and vet

Today was busy and exhausting. Workwise, I found a cool new Proof that the Earth is a Globe, that I didn’t even have on my list already, thanks to a reader. It was so cool, I wrote it up today!

In other news, I was preoccupied with Scully, who hasn’t been able to keep any food down since Monday night. She’s been sleepy, and refusing almost all food, and vomiting a few times. My wife took her to the vet today, and they did a blood test and x-ray, which both turned up all clear, so they suspect probably a stomach bug of some sort, which should hopefully resolve in a day or two. She’s got some anti-nausea medication to help keep her food down, and she’s eaten dinner with some gusto, so hopefully she’s okay.

Also, I baked some scones today, since my wife expressed a desire for some, and I thought it was a good idea to spoil her today.

New content today:

Proof writing

I spent most of today writing the next entry for 100 Proofs That The Earth is a Globe. I’ve almost finished it, but I won’t be able to post it tonight, so it’ll go up tomorrow.

The other big news is that today is Scully’s second birthday!

Scully's 2nd birthday

She got a cool new toy from Luna (the poodle next door) – a combo plush/rubber duck, and she had fun all day chewing it into little pieces…

I also did a big grocery shop today. We’re converting from 3 or 4 shops a week to try and stick to just one, as part of social distancing to avoid spreading/catching coronavirus. The supermarket was not busy, but they were still out of toilet paper and flour. I would like to get some breadmaking flour, to try some bread baking at home, but oh well. Maybe next time. We have plenty of everything else we need.

New content today:

Falling bodies

After a day of science yesterday, I also spent most of today doing science – this time writing up my latest Proof that the Earth is a Globe. That took pretty much the whole working day.

After finishing that off, I starting making dinner while my wife and Scully were out at the hospital doing their Delta therapy dogs visit. I bought kipfler potatoes on the weekend, planning to make potato salad at some point, and I figured I had just about enough time to get it done in time for dinner tonight. I boiled them up, and also made a couple of hard boiled eggs while doing that. I’m glad I’ve found an effective way to make the eggs so they’re easy to peel. I used have trouble peeling eggs until I stumbled across the technique of plunging them in iced water immediately after removing them from the boiling water. It helps a lot.

I also chopped and fried some onion – I normally use raw red onion which is milder, but I only had brown onions so I cooked it a bit to soften the flavour. And chopped some gherkins. Mixed it all together with some mustard and prepared coleslaw dressing. I know they make potato salad dressing, but I find coleslaw dressing to be more to my taste, with a bit more tang and less creaminess to it.

To serve with the potato salad I cooked up some vegetarian sausages – spicy Italian flavour, which had tomatoes and herbs in them – and some asparagus. It all turned out really nice.

Tomorrow morning is my first Ethics class for the year, meeting a new group of students. To prepare I printed out the lesson plan and went over it. It’s a simple introductory lesson, mostly about meeting the students, going through the rules of the class, and giving them a taste of the sort of things we discuss during the rest of the year. My job for this lesson is mostly about learning the names of the kids as quickly as I can! It took me four weeks last year to be able to go without name tags. Let’s see if I can beat it this year.

New content today:

Late for Thursday

I was so busy working on finishing off a new article for 100 Proofs that the Earth is a Globe last night that I neglected to update here, so this is another “next morning” post. Not that there’s much to report – working on that article is basically all I did yesterday, apart from the usual daily life stuff like eating and taking Scully for a walk.

I’ve read that writing 1000 words a day is a good pace for a professional writer. I write up to 2000 words in a day for these 100 Proofs articles, plus the research and often creating diagrams as well. So that’s a pretty hectic work pace and doesn’t really leave time for much else.

New content today: