A silly answer to an interesting question

See this and weep, Mr Mayo

Last night I heard some of Simon Mayo on Radio 2. (It was an accident, okay?) They asked quite an interesting question: 'How far can you see?' - but then accepted as if it were fact a totally silly answer. Someone had rung in to say that a British Airways pilot told him you could see up to 250 miles, or words to that effect. There are two problems with this.

First, I worked at BA for 17 years and met quite a lot of pilots, and many of them were jolly nice people. But almost all were great spinners of yarns. I wouldn't believe a word they said. More to the point, though, as presented, the question bears a considerable resemblance to that hoary old favourite 'How long is a piece of string?', because the proper answer is 'It depends what you are looking at.'*

The furthest anyone can see dwarves the 250 miles answer to a ridiculous extent, but let's work up to it. The human eye is actually very good at detecting photons - it only takes a few to trigger it. This means that on a clear, dark night you can see a candle flame around 10 miles** away, which is pretty impressive in itself.

But a candle isn't exactly hard to beat. Anyone seen the Moon? Yup. So have I. That's around 230,000 miles away. Makes 250 miles seem a little weeny doesn't it? And we haven't started. The Sun is further still, and stars take us out even further. But let's push it to the limit.

The generally agreed 'furthest thing away you can see' (subject to some superbright thing flaring up in the future) is the Andromeda galaxy. Want to find it? One of the most recognizable constellations is Cassiopeia. The five main stars of the constellation form a large letter W, which is hard to miss (though you may see it looking more like an M). But it’s not Cassiopeia itself we are interested in.
If you think of Cassiopeia as a W, treat the second V in the W as an arrow and follow its pointer by a distance that is about the same as the entire span of Cassiopeia. This will have taken you into the much less obvious constellation called Andromeda. And around the point you arrived, a little fuzzy patch of light is just visible with the naked eye.

That fuzzy smear is the Andromeda galaxy, the nearest large galaxy to our own Milky Way. But ‘near’ is a relative thing in intergalactic terms. The Andromeda galaxy is 2.5 million light years away. Let's do a bit of approximate maths to turn that into more familiar units. A light year is the distance light travels in a year. It goes around 186,000 miles a second, so that makes a light year around 186,000 x 3600 x 24 x 365.25 miles. Call it 5,869,713,600,000 miles. So the Andromeda galaxy is around 14,674,284,000,000,000,000 miles away. So the figure given on Simon Mayo's show was around 58,697,136,000,000,000 times too small.

Even by broadcasting standards, that's a pretty magnificent level of inaccuracy.

* This assumes, by the way, that we are talking about seeing with the naked eye, and someone who has good eyesight.

** For easy comparison with the 250 miles, I am abandoning my usual metric units, so those who don't use miles will have to grit their teeth and mentally multiply by 1.609 to get kilometres.

Image from Wikipedia

Why I hate opera

If I'm honest, the title of this post is an exaggeration to make a point. I don't really hate opera. There are a couple of operas - notably Monteverdi's Incoranazione di Poppea and Purcell's Dido & Aeneas - that I quite like. But what I do find truly sickening is the reverence with which opera is treated, as if it were some particularly great art form. Nowhere was this more obvious than in ITV's recent gut-wrenchingly awful series Pop Star to Opera Star , where the likes of Alan Tichmarsh treated the real opera singers as if they were fragile pieces on Antiques Roadshow, and the music as if it were a gift of the gods. In my opinion - and I know not everyone agrees - opera is: Mediocre music Melodramatic plots Amateurishly hammy acting A forced and unpleasant singing style Ridiculously over-supported by public funds I won't even bother to go into any detail on the plots and the acting - this is just self-evident. But the other aspects need some ex

Is 5x3 the same as 3x5?

The Internet has gone mildly bonkers over a child in America who was marked down in a test because when asked to work out 5x3 by repeated addition he/she used 5+5+5 instead of 3+3+3+3+3. Those who support the teacher say that 5x3 means 'five lots of 3' where the complainants say that 'times' is commutative (reversible) so the distinction is meaningless as 5x3 and 3x5 are indistinguishable. It's certainly true that not all mathematical operations are commutative. I think we are all comfortable that 5-3 is not the same as 3-5. However. This not true of multiplication (of numbers). And so if there is to be any distinction, it has to be in the use of English to interpret the 'x' sign. Unfortunately, even here there is no logical way of coming up with a definitive answer. I suspect most primary school teachers would expands 'times' as 'lots of' as mentioned above. So we get 5 x 3 as '5 lots of 3'. Unfortunately that only wor

Which idiot came up with percentage-based gradient signs

Rant warning: the contents of this post could sound like something produced by UKIP. I wish to make it clear that I do not in any way support or endorse that political party. In fact it gives me the creeps. Once upon a time, the signs for a steep hill on British roads displayed the gradient in a simple, easy-to-understand form. If the hill went up, say, one yard for every three yards forward it said '1 in 3'. Then some bureaucrat came along and decided that it would be a good idea to state the slope as a percentage. So now the sign for (say) a 1 in 10 slope says 10% (I think). That 'I think' is because the percentage-based slope is so unnatural. There are two ways we conventionally measure slopes. Either on X/Y coordiates (as in 1 in 4) or using degrees - say at a 15° angle. We don't measure them in percentages. It's easy to visualize a 1 in 3 slope, or a 30 degree angle. Much less obvious what a 33.333 recurring percent slope is. And what's a 100% slope

Search This Blog