Colour conundrum

Have you ever thought about how strange a concept 'shiny black' is? Read on, in a post inspired by a Twitter interchange with Steve Mould of Festival of the Spoken Nerd. (If you haven't seen their show, book now - it's great!)

What colour is the car in the picture?
It's black.
Are you sure?
Of course I'm sure. What's your point?
It's black?
YES! Okay?
Bear with me. How do you know it's black?
Because that's the colour it is.
And how do you know what colour anything is?
This is basic Newtonian stuff, isn't it? White light hits an object. White light is made up of all the colours of the visible spectrum. Some colours are absorbed, the rest re-emitted. And the colours that are re-emitted are the colours we see. Trivial.
So a postbox, for instance?...
Exactly. White light hits a postbox, which absorbs everything except the red photons, which re-emit. And amazingly we see a red postbox. I still don't get your point.
You will. What about a black object?
That's a bit of a special case. We say something is black when it absorbs the whole caboodle. It doesn't re-emit any colours of light. So arguably black isn't a colour at all, it's an absence of colour.
Spot on. So what colour is the car in the picture?
Black.
And yet it is emitting light. It's shiny. And what does shiny mean?
Unless you are a Firefly fan, it means, well, something that shines. The OED says 'Full of light or brightness; luminous...'
So how can that car be black, if it is full of (emitted) light? By your definition, the colour of something is the colour of the light it gives off. What colour light does the shiny car shine with?
Erm, white light?
Exactly. So by your definition of colour, this black car is white. Next we prove that 2+2=16 and rip off the Bank of England.

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