May the force not be with you: Sandra Bullock goes for a spacewalk in Gravity. Photo: Warner Bros
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In search of the notorious Big G: why we still know so little about gravity

Gravity is pathetic and so is our understanding of it.

Gravity is pathetic. The Oscar statuette, for instance, has a mass of 3.85 kilograms but it is pulled down to earth by a force so weak that you can buy a £2.99 fridge magnet that can beat it. It’s shameful that the gravitational pull of the entire earth can be overcome by a cheap piece of magnetised steel.

Gravity is by far the weakest of the fundamental forces of nature (the fridge magnet puts the far stronger electromagnetic force to work). It is so weak that its strength is proving difficult to measure accurately. In late February, while Alfonso Cuarón, the director of the sci-fi film Gravity, was on tenterhooks waiting for the Oscars result, the world’s experts on gravity assembled just outside Milton Keynes in an attempt to sort out this most embarrassing problem.

Numbers such as the strength of gravity, the speed of light and the charge on an electron are known to physicists as the “fundamental constants”. They are in some ways the sticking plaster of physics. We can explain the origin of most things but we know the values of the fundamental constants only by measuring them – there is no way to work them out from a theory.

These days, most are very well defined – but not gravity. It is the only fundamental constant for which our uncertainty over its value has got worse over the years.

The gravitational constant is sometimes known as “Big G”. This differentiates it from “little g”, which describes how fast things accelerate towards Planet Earth when free to fall. The first accurate measurement of Big G was made in 1798. Henry Cavendish used a torsion balance, a device in which two lead weights are attached to the ends of a metal bar. The bar hangs horizontally by a metal wire attached to its midpoint. Cavendish then brought other weights close to one of the lead weights and measured how much the gravitational attraction between the weights twisted the wire. From that measurement, he calculated the strength of gravity.

Cavendish’s accuracy was five parts in 1,000. Over 200 years later, our accuracy stands at roughly one part in 10,000. Given that modern measurements use lasers and electronic devices and Cavendish used a mirror and a candle, it hardly counts as a great improvement.

What’s worse is that our measurements of Big G are getting less accurate. The latest measurement, reported at the end of last year, reduced the overall value by 66 parts per million but the uncertainty
of the value increased from 100 parts per million to 120 parts per million.

The measurement was taken by Terry Quinn, emeritus director of the International Bureau of Weights and Measures in Paris. At its meeting in February, he argued that it was time researchers admitted that everyone must be making some basic errors in their method and that they should give up on making any more unilateral measurements.

The experts now agree that future experiments seeking the value of Big G will be done in big collaborations, with the proposals for equipment and methodology being scrutinised by everyone in advance to minimise the chance of further embarrassment.

It will, they say, mimic the way that researchers worked together to find the Higgs boson. That gave us the secret of mass: the hope is that if the physicists all pull together, they can finally work out exactly what size of force brings that mass down to earth.

Michael Brooks holds a PhD in quantum physics. He writes a weekly science column for the New Statesman, and his most recent book is At the Edge of Uncertainty: 11 Discoveries Taking Science by Surprise.

This article first appeared in the 05 March 2014 issue of the New Statesman, Putin's power game

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Forget fake news on Facebook – the real filter bubble is you

If people want to receive all their news from a single feed that reinforces their beliefs, there is little that can be done.

It’s Google that vaunts the absurdly optimistic motto “Don’t be evil”, but there are others of Silicon Valley’s techno-nabobs who have equally high-flown moral agendas. Step forward, Mark Zuckerberg of Facebook, who responded this week to the brouhaha surrounding his social media platform’s influence on the US presidential election thus: “We are all blessed to have the ability to make the world better, and we have the responsibility to do it. Let’s go work even harder.”

To which the only possible response – if you’re me – is: “No we aren’t, no we don’t, and I’m going back to my flowery bed to cultivate my garden of inanition.” I mean, where does this guy get off? It’s estimated that a single message from Facebook caused about 340,000 extra voters to pitch up at the polls for the 2010 US congressional elections – while the tech giant actually performed an “experiment”: showing either positive or negative news stories to hundreds of thousands of their members, and so rendering them happier or sadder.

In the past, Facebook employees curating the site’s “trending news” section were apparently told to squash stories that right-wingers might “like”, but in the run-up to the US election the brakes came off and all sorts of fraudulent clickbait was fed to the denizens of the virtual underworld, much – but not all of it – generated by spurious alt-right “news sites”.

Why? Because Facebook doesn’t view itself as a conventional news provider and has no rubric for fact-checking its news content: it can take up to 13 hours for stories about Hillary Clinton eating babies barbecued for her by Barack Obama to be taken down – and in that time Christ knows how many people will have not only given them credence, but also liked or shared them, so passing on the contagion. The result has been something digital analysts describe as a “filter bubble”, a sort of virtual helmet that drops down over your head and ensures that you receive only the sort of news you’re already fit to be imprinted with. Back in the days when everyone read the print edition of the New York Times this sort of manipulation was, it is argued, quite impossible; after all, the US media historically made a fetish of fact-checking, an editorial process that is pretty much unknown in our own press. Why, I’ve published short stories in American magazines and newspapers and had fact-checkers call me up to confirm the veracity of my flights of fancy. No, really.

In psychology, the process by which any given individual colludes in the creation of a personalised “filter bubble” is known as confirmation bias: we’re more inclined to believe the sort of things that validate what we want to believe – and by extension, surely, these are likely to be the sorts of beliefs we want to share with others. It seems to me that the big social media sites, while perhaps blowing up more and bigger filter bubbles, can scarcely be blamed for the confirmation bias. Nor – as yet – have they wreaked the sort of destruction on the world that has burst from the filter bubble known as “Western civilisation” – one that was blown into being by the New York Times, the BBC and all sorts of highly respected media outlets over many decades.

Societies that are both dominant and in the ascendant always imagine their belief systems and the values they enshrine are the best ones. You have only to switch on the radio and hear our politicians blithering on about how they’re going to get both bloodthirsty sides in the Syrian Civil War to behave like pacifist vegetarians in order to see the confirmation bias hard at work.

The Western belief – which has its roots in imperialism, but has bodied forth in the form of liberal humanism – that all is for the best in the world best described by the New York Times’s fact-checkers, is also a sort of filter bubble, haloing almost all of us in its shiny and translucent truth.

Religion? Obviously a good-news feed that many billions of the credulous rely on entirely. Science? Possibly the biggest filter bubble there is in the universe, and one that – if you believe Stephen Hawking – has been inflating since shortly before the Big Bang. After all, any scientific theory is just that: a series of observable (and potentially repeatable) regularities, a bubble of consistency we wander around in, perfectly at ease despite its obvious vulnerability to those little pricks, the unforeseen and the contingent. Let’s face it, what lies behind most people’s beliefs is not facts, but prejudices, and all this carping about algorithms is really the howling of a liberal elite whose own filter bubble has indeed been popped.

A television producer I know once joked that she was considering pitching a reality show to the networks to be called Daily Mail Hate Island. The conceit was that a group of ordinary Britons would be marooned on a desert island where the only news they’d have of the outside world would come in the form of the Daily Mail; viewers would find themselves riveted by watching these benighted folk descend into the barbarism of bigotry as they absorbed ever more factitious twaddle. But as I pointed out to this media innovator, we’re already marooned on Daily Mail Hate Island: it’s called Britain.

If people want to receive all their news from a single feed that constantly and consistently reinforces their beliefs, what are you going to do about it? The current argument is that Facebook’s algorithms reinforce political polarisation, but does anyone really believe better editing on the site will return our troubled present to some prelap­sarian past, let alone carry us forward into a brave new factual future? No, we’re all condemned to collude in the inflation of our own filter bubbles unless we actively seek to challenge every piece of received information, theory, or opinion. And what an exhausting business that would be . . . without the internet.

Will Self is an author and journalist. His books include Umbrella, Shark, The Book of Dave and The Butt. He writes the Madness of Crowds and Real Meals columns for the New Statesman.

This article first appeared in the 24 November 2016 issue of the New Statesman, Blair: out of exile