Things I apparently need to bear in mind before reading Man who was Thursday

* It's apparently more like a parody of pointlessness, not an endorsement thereof
* For "anarchist" read more like "terrorist", regardless of the truth, a type of people who the public are genuinely scared are going to be blowing stuff up
* Nefarious plans by subversive groups being run primarily by uncover policemen is ridiculous, not the norm.

This is more of a life lesson, but:

* If you're recruited as a police officer or agent, and there's a bunch of justification but not a giant pile of bureaucracy, it's probably some sort of scam.

Preventing traffic jams by driving at constant speed

Every so often I hear someone talking about modelling traffic jams as waves travelling in a queue of cars. After some thought, I came to some tentative conclusions, without having actually tried any modelling or anything.

Imagine a long long stream of cars along a somewhat congested motorway without much overtaking.

The first observation is, whatever you do, you can't really affect the car in front as long as you're driving legally/safely. And whatever you do, you don't end up significantly behind them: if there's any sort of traffic, the average speed is much under the fastest speed you could drive in an empty road, so you can always catch up with them. So whatever you do, *you* will reach your final turnoff shortly after the car in front.

However, over a long run of cars, it seems plausible (I haven't double-checked the maths) that cars driving at 30mph have a greater throughput than ones alternating 60mph and 0mph, mostly due to needing more than twice the distance between at 60 than at 30. That means that if traffic is dense, there's a natural tendency for small disruptions to sometimes get magnified, when each car reacts a little slowly to the car in front, and hence makes a slightly larger correction. Whereas if you go a bit slower and give yourself a bit of extra space when the traffic in front of you starts of but you suspect it's more stop-start, hopefully the traffic behind you will experience *less* disruption.

I'm not sure, does that sound right?

Aunt Vera Explains Relativity

As I passed Aunt Vera's, I wandered up to the open garage to see how she was doing. A week ago, she had borrowed mum's bar billiard's table. Mum had said it would be good for her to give the mad science a rest occasionally and try a different hobby. I was excited to see what she'd turned it into.

As I peered into the garage, she was indeed tinkering madly with the billiard table. Four steam funnels rose from the corners, and a dense web of different wires wended between them almost creating a wall round the table a meter above it. At the head of the table, dozens of different dials had been wedged onto a narrow wooden board, several resting at awkward angles suspended by the wires and pipes plugged into them.

I must have made a noise, as she suddenly spun around, labcoat and goggles swirling about her. "Ah, Sarah! What perfect timing. I have a lot to show you."

"Uh. My parents are going to be cross if I'm late for dinner agian. And I was going to call Carol later."

"Pish!" she exclaimed. "Pish-tosh! "This is Educational, and they will appreciated you being educated,"

"But I am being educated," I protested. "I have homework and everything. Homework I need to get done, if I'm going to call Carol before 10."

"Pish!" she said again. "Is Carol going to show you how quantum mechanics works?"

"Well, I don't expect so-" I began.

"Well then!" she announced with finality. "You need me to do it. No niece of mine is going to go to university with a piddling A-level knowledge of quantum mechanics."

"But, Aunt Vera, they don't teach quantum mechanics at A-Level. Not even in physics. And I'm studying Biology, and Economics and Japanese, and..."

"PRECISELY MY POINT", she yelled, a foot from my ear. "You would swan off to university with no knowledge of physics, the very forces which stop you falling through the ground. Did I tell you about my adventure of the intangibility harness and the Earth's crust?"

"Aunt Vera", I shouted, and winced as I realised how loud I was screaming. But she stopped, a bit put out, and I continued. "I'm not a physicist." She looked heartbroken, and I tried to school myself not to fall for it. "But I'd love to see what you've--"

"Excellent," she crowed, and dragged me up to the table. Wires festooned the edges, and at the top where the score used to be, a bank of complicated dials and levels waited.

I toyed with the idea of a comic fantasy style explanation of what I'd learned about relativity. Unfortunately, I really loved how the byplay turned out, but the actual explanation didn't work well. There's a lot more, but it's mixed "fun arguing" and "didactic bad explanations".