NanoSapiens » Mathematics

Comedians regale skeptics with tales of cats in space and aliens in Ancient Britain

Science news, comment and analysis | guardian.co.uk — Fri, 21 Jan 2011 14:27:45 +0000

Stand-up comedians Helen Keen and Matt Parker perform for Skeptics in the Pub at the Monarch in Camden on 23 December

Learn to love uncertainty and failure, say leading thinkers | Edge question

Alok Jha — Sat, 15 Jan 2011 05:00:00 +0000

Earth’s biggest beans defense this year’s Whet cross-examine: ‘What scientific thought would ameliorate everybody’s cognitive toolkit?’

Entity cheerful accompanying suspicion, wise the contracts of what education can instruct us, furthermore knowledge the value of washout are total important files that would correct community’s exists, according to several of the macrocosm’s first minds.

The concepts were submitted as role of an flower ply by the fabric journal Margin, which bids scientists, thinkers plus sculptors to deem on a big debate of the importance. This year it was, “What scientific opinion would ameliorate everybody’s cognitive toolkit?”

The journal called for “shorthand abstractions” – a path of encapsulating an supposition or scientific notion toward a crisp definition that could be secondhand as a part of bigger demurs. The retorts were published online today.

Innumerable retorts sharp absent that the society frequent misconstrues the scientific writ also the constitution of scientific mistrust. This can combustible popular quarrels finished the value of controversys among scientists about questionable emanates such as temper permutation further vaccine shelter.

Carlo Rovelli, a physicist at the School of Aix-Marseille, emphasised the uselessness of confidence. He said that the idea of something person “scientifically proven” was almost an oxymoron furthermore that the quite pedestal of skill is to guard the entrance start to doubt.

“A propitious scientist is never ‘incontrovertible’. Shortage of sureness is precisely what assembles inferences further stable than the periods of those who are unerring: since the benevolent scientist determination be available to vacillate to a another significance of regard if promote ingredients of testify, or original discourses dawn. Wherefore assurance is nay solely something of no duty, b

The US embassy cables enigma | Jonathan Farley

Jonathan Farley — Thu, 23 Dec 2010 13:09:57 +0000

Don’t want people to read your stuff? Easy – send it in code. So why didn’t the state department make itself WikiLeaks-proof?

When I was an undergraduate at Harvard, an astronomer from Berkeley came over to the physics building to give a talk. His name was Cliff Stoll, and he didn’t give a talk about astronomy. He gave a talk about accounting.

I remember the details less than Stoll’s frizzy Eurofro and his jumping around the front of the lecture hall as if he were on something Miley Cyrus might like to try. For some reason, this astronomer worked on computers, and one day, he noticed a 75-cent accounting error, a phone bill discrepancy or something like that. Normally, someone who is only interested in estimating the age of the universe up to a few billion years ought not to be so concerned with a 75-cent error, but Stoll did care.

It led him to a German KGB spy ring paid in cocaine. But that’s his saga. My point is that once Stoll figured out that spies were slipping into his computer system, he laid a trap: a file called “Star Wars”, referring to the Strategic Defence Initiative.

The “Star Wars” file was big but it was fake. It contained nothing valuable. Maybe a recipe for really excellent-tasting cherry bakewells or something like that, but that’s all. It was sweet enough to entice the spies, and large enough to keep them on the system long enough for Stoll to trace them. Gotcha.

A propos, what’s surprising about the US state department/WikiLeaks scandal is that there is a scandal. As a friend reminded me, these days, it’s really quite easy to make sure no one can read your messages, unless you want them to.

The science of cryptography has been around for ages. One of the simplest codes was used by Caesar. He would send secrets simply by shifting the letters of the message a few notches down the alphabet: “Mw xlex e hekkiv sv evi csy nywx lettc xs wii qi?” (Ouch!) I should point out that this kind of code is easy to break, since an interceptor can do some statistical analysis and figure out how many letters you have shifted down the alphabet by comparing the most common letter in your message with the letters that appear most frequently in your language. (I should perhaps further point out that this code is only easy to break if you’re not a barbarian Gaul. They did not have good schools.)

In the second world war, the Germans developed a device that, they believed, produced an unbreakable code: the Enigma machine. It resembled a typewriter, with a series of gears and wheels that produced a different letter each time you typed the same key.

And if, by chance, the Allies figured out this more complicated version of the Caesar shift, the next day the Germans could reset the keys and the Allies would have to figure the code out again, starting from scratch.

The problem was that Germans may be efficient when it comes to tram schedules, but not so much when it comes to resetting Enigma machines. The Allies, led by the likes of Cambridge mathematician Alan Turing, and with the help of Polish codebreakers, used high-speed, electronic computers that could work just fast enough to figure out Enigma’s “unbreakable” code.

It would seem there is no unbreakable code. For every scheme, you just build a faster computer to crack it, right?

Not necessarily. It’s possible that there may be a theoretical limit to how quickly you can perform certain tasks called “NP-complete problems” – the “N” standing for “non-deterministic Turing machine” – that you would need to be able to perform quickly if you wanted to break codes in less time than it would take monkeys to type Hamlet. If so, and we think it is so, all you’d need to do to keep third parties from reading your messages is to take two really, really big prime numbers – say, with 200 digits each – and multiply them together. (It’s OK to use calculators.)

The method is called “public key cryptography”. It’s really all the rage, and I’d be a bit surprised if US Secretary of State Hillary Clinton, whose cables have been leaking out, didn’t know about it. The people up the road at the NSA certainly do.

The National Security Agency is a riddle wrapped in a mystery inside a code. It dwarfs the CIA. And, most disturbing of all, it is the world’s largest employer of mathematicians. And they’re really, really good at multiplying.

Roughly, the idea behind public key cryptography is that you have one prime; the intended recipient has the other; and the message is transmitted openly using the product of the numbers (or perhaps using an exponential version of the Caesar shift). Anyone can pluck the message out of the air, but factoring a giant number may be like one of those NP-complete problems. Even Turing machines can’t do it quickly, we think.

So, when it comes to WikiLeaks obtaining US diplomatic cables, either no one at the US state department had ever heard of cryptography, or they were too lazy to care, or –

Gotcha.

Jonathan Farley

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Mobile phone radiation linked to people jumping to conclusions | Matt Parker

Science news, comment and analysis | guardian.co.uk — Mon, 20 Dec 2010 12:33:55 +0000

Mathematician Matt Parker explains why he issued a hoax press release linking the number of mobile phone masts to births

There has never been clear evidence that mobile phone radiation can cause any form of biological effect. In fact there are no known processes whereby mobile phone radiation could impact anyone’s health.

This does not mean there are no correlations that link mobile phone radiation with biological processes. Last Friday I appeared on the BBC Radio 4 maths show More or Less and wrote in the Guardian about the strong correlation between the number of mobile phone masts and the number of births in the same area. I immediately explained that this was only a correlation based on the fact that both transmitter tower numbers and births are dependent on population size, and so the figures change in unison as a population changes.

My article was actually explaining how I was using this as an example of correlation where there is no causality, and I had put it out as a press release to see whether media outlets would jump to the incorrect conclusion that mobile phone radiation causes pregnancies.

As it turned out, I did not need to look to other media outlets for evidence that people are willing to jump to a specious correlation-based conclusion; I merely needed to scroll down to the comments beneath my article. There are the expected people who clearly did not actually read what I wrote before seeing the headline and getting excited about this apparent scare story, but there are also seemingly endless comments from people who understood my correlation-causality project but could not help putting forward a possible causal link anyway. It is such a hard-wired instinct to assume there must be causality at play.

It is reassuring but unentertaining that no mainstream media outlets took the bait without fact-checking the press release, which does gives me some hope. We did, however, give them every chance: the press release did not have a university affiliation, it was only sent to generic news desks instead of specific journalists and we let our correlation ploy out of the bag as soon as anyone phoned to check the story.

What concerns me is that more insidious cases of correlation results do still get widely picked up and reported as causal. In early December 2010 there was a story about mobile phone use during pregnancy being linked to later misbehaviour in the child. With all the possible confounding factors across schooling, parenting, environment and genes there is a quagmire of correlation from which it is almost impossible to extract a thread of causality. This slight correlation was reported widely with headlines such as: “Warning for mums-to-be: Using phone while pregnant can lead to behavioural problems in children”. This causal link should be at the very end of a long list of possible explanations for the correlation.

Places like the Science Media Centre work with the countless journalists who try hard to ensure health reporting is accurate, but these scare stories still consistently crop up. The good news is that the more information about correlation and statistics people have, the better equipped they will be to overcome the natural desire to leap to causality conclusions. Or maybe that’s just a coincidence.

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Mobile phone masts linked to sharp rise in birth rate | Matt Parker

Matt Parker — Fri, 17 Dec 2010 12:32:34 +0000

Mathematician finds a strong correlation between the presence of mobile phone masts and the number of children born

Do mobile phone towers make people more likely to procreate? Could it be possible that mobile phone radiation somehow aids fertilisation, or maybe there’s just something romantic about a mobile phone transmitter mast protruding from the landscape?

These questions are our natural response to learning that variation in the number of mobile phone masts across the country exactly matches variation in the number of live births. For every extra mobile phone mast in an area, there are 17.6 more babies born above the national average.

This was discovered by taking the publicly available data on the number of mobile phone masts in each county across the United Kingdom and then matching it against the live birth data for the same counties. When a regression line is calculated it has a “correlation coefficient” (a measure of how good the match is) of 98.1 out of 100. To be “statistically significant” a pattern in a dataset needs to be less than 5% likely to be found in random data (known as a “p-value”), and the masts-births correlation only has a 0.00003% probability of occurring by chance.

The match between mobile phone towers and birth rates is an extremely strong correlation and it is highly statistically significant. There is no doubting the mathematical finding that more mobile phone masts mean that there will also be more births. This is about as rigorous as statistics can get.

Mobile phone masts, however, have absolutely no bearing on the number of births. There is no causal link between the masts and the births despite the strong correlation. Both the number of mobile phone transmitters and the number of live births are linked to a third, independent factor: the local population size. As the population of an area goes up, so do both the number of mobile phone users and the number people giving birth.

The problem is that our first instinct is to assume that a correlation means that one factor is causing the other. While this does not cause a problem when using pattern-spotting as an evolved survival tool, it does cause severe problems when assessing possible health scares based on a recently uncovered correlation. For the majority of cases, correlation does not indicate the presence of causality.

To investigate a possible causal link requires careful mathematical untangling of false-positive correlations. This is what a team of researchers did at Imperial College London when they were looking for a link between childhood cancer and exposure to radiation from mobile phone transmitters. They obtained location data for 1,397 children who had experienced some form of childhood cancer. For each of these children, they then found four random children who had been born at the same time but had never had cancer. These two case groups were then compared in terms of the number and strength of mobile transmitters where their mothers lived during pregnancy and their early childhood.

This particular study into childhood cancers – along with every other robust study investigating possible links between mobile phones and health – found no causal link.

But would the media turn a correlation-only finding into a causation-based health scare? To find out, I have released my mobile masts and births results as a press release. We’ll see if anyone jumps to the conclusion that mobile phone radiation really can give conception a helping hand.

Listen to Matt discuss his finding on More or Less, BBC Radio4 at 13:30 today, Friday 17 December. Or check the Guardian website on Monday 20 December to see what Matt reports back.

Data sources

Ofcom “Sitefinder” data

England and Wales Live Birth data

Scotland Live Birth data

Northern Ireland Live Birth data

Matt Parker

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