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

Chicago Daily News
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7 adorably wrong retro visions of the future

With the future looking gloomier than ever, let's take a look at what could have been.

Ah, the future. The golden, glorious future. A time when food will be replaced by pills, walking will be replaced by hovering, and someone will have finally invented a printer that will print your black and white theatre ticket even though (even though!) you have an empty magenta ink cartridge. Who can wait? 

Unfortunately, what with the end-of-the-world-as-we-know-it (see: Trump, Donald J) the future seems less and less spectacular everyday. Is it time to build an underground bunker? Who can say? I can. The answer is yes.

But while you're waiting for your Spaghetti Hoops to heat up in your concrete hidey-hole, you'll need something to read. Here are seven futures that we could have had, if it wasn't for fascism (and also, I guess, the fact that some of these are really dumb).

1. Commuter helicopters

Popular Mechanics (1951) via Flyingcarsandfoodpills.com

What they predicted: Personal helicopters which would transform commuting forever. 

Why it didn't happen: Because apparently Future Us are sufficiently advanced enough to create mini, personal helicopters, but not smart enough to have grasped the concept of a helipad. 

2. Instantly-cookable food

Via Reddit u/Jaykirsch

What they predicted: Food that can be heated or chilled instantly within its packet, by the turn of a knob.

Why it didn't happen: Remember in 2005 when Walkers Worcester Sauce crisps were recalled because it was thought they'd give you cancer? Yeah, that. 

3. Space puppies

Amazing Science Fiction (1958) via Pulparchive.com 

What they predicted: Space puppies. Puppies in space.

Why it didn't happen: Because God enjoys our pain.

4. The "Dinosaur Truck" elevated bus

The Practical Science For Boys And Girls (1949) via Darkroastedblend.com

What they predicted: Buses that could seamlessly glide over cars, carrying us onwards to a new and better future.

Why it didn't happen: It did! China have it. Well done China.

5.  A radio that prints newspapers

Radio Craft (1934) via Tarzan.org

What they predicted: A radio that could print out your morning newspaper, with some kind of nice little red thing on top.

Why it didn't happen: All media is obsolete. You are not even reading these words. Unless you're my mum. Hi mum. 

6. A robot that hits children on the head if they don't listen in class

Computopia (1969) via Pinktentacle.com

What they predicted: A robot that hits children on the head if they don't listen in class.

Why it didn't happen: Whilst our robotics are advanced enough, it turns out so too are our morals. Bummer.

7. Wrist computers

Byte (1981) via archive.org

What they predicted: Little computers that will sit on your wrist, like a watch.

Why it didn't happen: You might be gaping and gawping that someone in 1981 successfully managed to predict the Apple Watch, but you'd be wrong. Take another look - see that tiny keyboard? No one could use that tiny keyboard. What were our ancestors thinking? Idiots. 

Amelia Tait is a technology and digital culture writer at the New Statesman.