## Plus Blog

February 24, 2009
Tuesday, February 24, 2009

### Life's an algorithm

It's not often that maths makes it into the mainstream media, and when it does, it's usually a very specific bit of maths — a statistical result or a certain application — that's being examined. An article published yesterday on the Guardian website makes a nice exception. It explores how maths underlies almost every aspect of modern life, from traffic lights to iTunes. Thank you, Guardian!

You can find out more about some of the topics mentioned in the article on Plus:

posted by Plus @ 11:45 AM

February 20, 2009
Friday, February 20, 2009

### We're doomed, say scientists

Sometimes a boring story can become a lot more interesting if you do some skilled number juggling. This is what seems to have happened in an article in The Daily Telegraph, which claims that 90% of us carry a gene which increases the risk of high blood pressure by 18%. And high blood pressure is of course linked to dreaded killers like stroke and heart disease.

In his Understanding Uncertainty blog David Spiegelhalter traces the story back to a paper in Nature Genetics. The authors of the paper investigate three gene variants that can occur in the human genome. Two of them are rare, only about 10% of the population carry them, while the third is present in 90% of the population. The authors show that the gene variants are associated to proteins called natriuretic peptides, which are linked to blood pressure (this is the main point of the paper, since such a genetic connection had never before been found). The two rarer gene variants, according to the paper, reduce the risk of high blood pressure by 15%. The phrase "18% increased risk of high blood pressure" appears nowhere in the paper. Rather it's the result of some creative accounting on the part of someone operating in the media chain which links the actual paper to the final article in The Daily Telegraph. Here's how it's done:

Say that the risk of high blood pressure for someone carrying the more common gene variant is x. Now the 15% decrease associated to the two less common variants takes this down to 0.85x. To get back to x, we need to add 0.15x, and this is exactly 17.647% of 0.85x — hence the claim of an 18% increase in risk.

The calculation is undoubtedly correct, but it puts a spin on the story. Rather than taking the common case as a base line and talking about the risk reduction associated to the less common cases, it does things the other way around. This is in stark contrast to the paper's authors own turn of phrase, which links the rarer variants to risk reduction, but says that the common variant "was not significantly associated with either systolic or diastolic blood pressure." It's a bit like noting that some people live to 110 and then complaining that most of us die prematurely. "This is a masterful piece of re-framing of the evidence," says Spiegelhalter on his blog. "Not exactly wrong, but definitely changing the story. Just like a change from 98% to 96% in a survival rate seems a lot more innocuous than a doubling of the mortality rate from 2% to 4%."

If you'd like to find out more about risk and uncertainty, visit the Understanding Uncertainty website, or read Spiegelhalter's column in Plus.

To find out more about simple number smoke screens, read the Plus article The tiger that isn't.

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posted by Plus @ 1:01 PM

February 18, 2009
Wednesday, February 18, 2009

How many arms does a spiral galaxy have? Can you spot a galaxy with a "peanut" bulge? Or how about a galactic merger? You — yes, you — can answer these and other strange questions, along with other ordinary web users who, by working together, have proven to be just as good at galaxy-spotting as professional astronomers.

Find out how you can help classify the inhabitants of the Galaxy Zoo!

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posted by Plus @ 5:21 PM

February 18, 2009
Wednesday, February 18, 2009

### Finally, recognition for string theory

Image from icanhascheezburger.com

Better than a celebrity endorsement, string theory now has a feline spokeskitten! (Thanks Oli for letting us know the good news!)

Why not educate your animal friends with these Plus articles:

posted by Plus @ 12:07 PM

February 17, 2009
Tuesday, February 17, 2009

### Zero is the number of yearning... review of Strange Attractors: Poems of love and mathematics

Zero is a number
of yearning.

— from "Five Poems about Zero" by Eryk Salvaggio

It's not often I get misty-eyed reading a book about mathematics, but that was just what happened when I read this, and several other poems, in the poetry collection Strange Attractors: Poems of love and mathematics.

The idea of a love poem is not new, love has inspired poets for millennia. But the combination of maths and love poetry might seem an odd mix. Despite loving maths myself, I was a little skeptical when I picked up this book, and thought it would be a tongue-in-cheek selection of witty but humorous poems about love using mathematical language and imagery. There are some funny poems giving a mathematical take on love, (I particularly liked "Valentine" by Michael Stueben), but what pleasantly surprised me was the large number of poems that seem to be really exploring human emotions.

I had no idea there would be so many poems suitable for such a collection, or that it would span so many centuries and include so many diverse contributors. The excerpt from King Solomon's "Song of songs" (which is thought to have been written about 765 BC) and Bhaskaracharya's "Lilavati" (a twelfth century Indian mathematician), the "Square Poem in Honor of Elizabeth I" (written by Henry Lok in 1597), as well as contemporary poets from nearly every continent, give the collection significant cultural depth (helpful appendices give brief biographies of both the contributors, and the mathematicians mentioned). It's a nice thought that mathematics, as well as love, is a ubiquitous experience for all of humanity.

The book is divided into three sections: romantic love, love of family and life, and love of mathematics. In the first two sections it is surprising just how powerful mathematics can be as a metaphor for our emotions and experiences. Some poems very effectively use mathematical imagery, such as the image of tangential curves ("kissing curves") in Ann Calandro's poem "Where the Kissing Never Stops":

They strive to make each other
equal zero
to reach that point
at which they will reduce to lines
and kiss...

or in Young Smith's "She Considers the Dimensions of Her Soul":

The shape of her soul is a square.
She knows this to be the case
because she often feels its corners
pressing sharp against bone...

The collection features some of the most famous love poems, such as Elizabeth Barrett Browning's measuring of love in her sonnet: "How do I love thee, let me count the ways...". One of the most interesting poems using counting is "Who Counts, Counts" by Stephanie Strickland, where the shifting status of relationships, and the bond of motherhood, was conveyed very simply by counting and recounting the people in a relationship.

Some of the poems have a mathematical structure, one is even written in the form of a proof. In some poems mathematical concepts are used as metaphors, such as Robin Chapman's sad use of the non-associativity (f(x+y) not equally f(x) + f(y)) to describe a child's experience of divorce in "Nonlinear Function".

The final section, where poets (many mathematicians) write about their love of maths, also has many examples of strong expression, and strangely enough, many of these poems seem almost less mathematical than in the previous sections. It is nice to see the passion for the subject that so many mathematicians share expressed in this unusual and open-hearted way. I think one of the strengths of such a book is that not only can it show people who are looking for poems to express love, the beauty of the language of maths, but it also might help explain some of the deep emotions mathematicians feel for their subject. I also like the duality of combining maths and poetry: that as well as taking maths to poetry lovers, it will also expose mathematicians to poetry, and perhaps as the best artistic-scientific collaborations do, allow insight on both sides.

Book details
Strange Attractors: Poems of Love and Mathematics
Edited by Sarah Glaz and JoAnne Growney
Hardback — 250 pages
A K Peters
ISBN-10: 1568813414
ISBN-13: 978-1568813417

posted by Plus @ 11:36 AM

At 2:16 PM,  Anonymous said...

Book information:

Strange Attractors: Poems of love and mathematics

edited by Sarah Galz and JoAnne Growney

ISBN: 978-1-56881-341-7

Publisher website: http://www.akpeters.com/product.asp?ProdCode=3417

February 16, 2009
Monday, February 16, 2009

### Post-Valentine's mathematical love

We're not sure if they've got Internet access on cloud 9, but for all the loved-up Valentines out there, as well as for those who are wondering what has gone wrong, here are some mathematical musings on love...

• Is your relationship like a convergent series? Victoria Gould and Marcus du Sautoy discuss this and other mathematical metaphors for the human condition in our latest career interview (podcast) and article on the Complicite production A disappearing number (podcast).
• What's your strategy for love? Hold out for The One, or try and avoid the bad ones? How long should you wait before cutting your losses and settling down with whoever comes along next? Let statistics help you live happily ever after by reading Kissing the frog: A mathematician's guide to mating.
• We all know that love's a gamble. Delve into the application of game theory to love and find out if it's worth buying that expensive present after all.
• There are not many concepts that are fundamental to both maths and sex, but symmetry is one of them. In maths the study of symmetry forms the basis of a vast field called group theory and can be exploited to understand the patterns inherent in nature and the abstract world. Scientists have long suspected that the symmetry of a person or animal's body is an indicator of health and strength and therefore desirability as a potential mate. So does it make us more attractive?
• And finally, does the Golden Ratio really have anything to do with beauty?