Notes and queries

All the colours of the rainbow, plus a few extra; What personalised car number plates say about their owners; The X Factor from outer space
rainbow inventing colours notes and queries
Into the blue ... or is it cyan? Photograph: Lewis Whyld/PA

Would it be possible to invent or discover a new colour?

Philosophers invent colours all the time. How about "eulb"? AJ Ayer defined this as the colour that something is if it is not blue. Or "grue", which is used (after the American philosopher Nelson Goodman) to apply to all things examined before a certain time, t, just in case they are green, but to other things just in case they are blue.

Bill Johnston, Arnside, Cumbria

It is usually said that there are seven colours in a rainbow. I have seen an eighth colour, but it's hard to describe.

Paul Geach, Launceston

This is a quandary that fascinated the five-year-old me at playgroup. Having learned that yellow plus blue made green and blue plus red made purple, I logically determined that if I mixed enough different colours I would discover a new colour. Sadly, my experiments always resulted in a sheet of craft paper covered in a muddy brown mess.

Nicola Tanner, Bristol

It's possible, and it has been done: cyan, a shade of blue, is a theoretical colour. It can be assigned a wavelength in the visible spectrum, but it never occurs in nature. It is, however, essential for modern colour printing. Because there is no cyan pigment, inks of an approximate colour are used and the deficiencies made up for by adjusting the other two colour inks.

William Saunders, London N19

What do personalised car number plates tell us about their owners?


David Scott, Newcastle upon Tyne

In the US, personalised number plates are cheaper and more common than in the UK, and are often jocular (eg TOM8TO). However, there is a social divide. Some years back a New Yorker cartoon depicted a conventionally dressed father telling a small, disappointed-looking boy: "I'm sorry, son, we're just not the kind of people who have amusing license plates."

Alison Finch, Cambridge

Their names, mostly, or their initials.

Chris Parkins, Stanmore, Middx

A colleague used to refer to "pratalised" numberplates.

Janet Atkinson, Stockton-on-Tees

P111 OCK

Alan Payling, Babbacombe, Devon


Robert Walker, Kinross


Georges Pauli, Witham, Essex


Milan Pathak, Baden, Switzerland

We are told that all life on Earth originates from a single microbe event, proven by DNA. So what are the odds on life existing elsewhere?

The astronomers Fred Hoyle and Chandra Wickramasinghe put forward the idea of Panspermia – that microbes from other planets could be deposited on Earth by space debris. It has been shown that rocks from the moon and elsewhere in the solar system can find their way to Earth. That this might be the origin of life on Earth is unproven, but it still wouldn't explain where this alien life originated.

But if such life could exist elsewhere, there is no reason to suppose that life could not originate also on Earth. It is now estimated that there are at least 2bn Earth-like planets in our galaxy, and no doubt the same number in Andromeda and in all the other billions of galaxies in the universe. It is almost inconceivable, then, that life has not begun many times over on some of these other planets. 

That we have not yet detected their TV transmissions of The X Factor and Strictly Come Dancing probably means that they are just too far away for the signals to have reached us. Our galaxy alone is 100,000 light years across.

Terence Hollingworth, Blagnac, France

Are there any houses with more than one blue plaque?

It's not a house, but the old physics laboratory in the University of Manchester has two, one on each side of the main entrance. The first commemorates Professor (later Lord) Ernest Rutherford, famous for discovering that the atom has a tiny dense nucleus with orbiting electrons (rather than being like a plum pudding with the electrons embedded in a positively charged dough) – the "nuclear" atom. The second commemorates Alison Uttley whose books, particularly those featuring my hero Sam Pig, I devoured when a small child. She was a physics undergraduate there – for me, a very happy juxtaposition.

John Galloway, London WC1

Any answers?

Is there any use for old VHS cassettes? My pal has 14,000 of them.

Andrew Cooke, Marton, Warks

Why, when I put cut tulips in water, do they continue to grow taller?

Judith Kent, Barnet

The world, of course, is going to hell. But why in a handcart?

Patrick Green, Edinburgh


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