Two or More Main Ideas

Why the Rails Are That Far Apart

Standard gauge is 4 feet 8½ inches. It is a strange number, and the reason is historical rather than engineering. Early railways were built by people who had built tramways for collieries, and those had used the wheel spacing of the carts already in use. Nobody chose it; it was inherited. Isambard Kingdom Brunel did choose. He built the Great Western at 7 feet ¼ inch, and by most measures it was better: faster, steadier, and able to carry more. He lost anyway. By the 1840s, more of the network was already standard gauge, and a train cannot run on a track it does not fit. Parliament settled it in 1846. Between 1846 and 1892 the Great Western converted its entire route. The final conversion took a single weekend and about four thousand men. The best design does not always win. The one that connects to everything else does.

Can You Do Two Things at Once?

People say they multitask. Mostly they do not. The brain can run two tasks together only if at least one is automatic. Walking and talking works because walking is automatic for an adult. Reading and listening to speech does not, because both need the same language system. What feels like multitasking is usually rapid switching. Each switch costs time — a fraction of a second to disengage and re-engage — and the costs add up. In experiments, people doing two tasks alternately take substantially longer in total than doing them one after the other, and make more errors. They also do not notice. Switching feels efficient because you are busy the whole time. The practical conclusion is unpopular but consistent: for anything demanding, doing one thing at a time is faster.