Hiding in plain sight

The Easter holiday rush is receding into distant memory. The only thing airport security personnel have to worry about is what happens when everyone starts arriving for the Olympics. That, and the helpful physicists who have worked out how to smuggle a gun through a metal detector.

It all started as a bit of harmless blue-sky thinking. In the late 1960s, a Russian physicist pointed out the fun you could have if you invented a material that bends light in the opposite direction to normal. You could use it as an invisibility cloak, he said: just as water diverts round a rock in a stream by going first to one side, then back to the other, light bent in two different directions as it passed an object would give a viewer the impression that the light had travelled in a straight line and that the object simply wasn’t there.

Oh, how everybody laughed. Then, in 2000, someone turned this ridiculous fantasy into reality. John Pendry of Imperial College London showed how to create “left-handed materials” that would bend microwave radiation the wrong way. The practicalities were a little cumbersome and it didn’t work with visible light. But still, it was surprising, impressive and fun, in a nerdy kind of way.

Over the past decade, the technology has matured. At first, left-handed materials were constructed from intricate arrays of copper rings and could only hide tiny objects from a microwave detector. Now, we have invisibility “carpets” made from cheap and widely available crystals of the mineral calcite. They are able to hide objects the size of your thumb – and they work in visible light.

That technology is not yet going to smuggle a gun through airport security, though. Even if the X-ray machine doesn’t make the outline obvious, the magnetic field from the steel triggers an alarm. But a paper recently published in the journal Science can get you round that obstacle.

As it turns out, you can cloak a metal’s magnetic field for less than £1,000. First, wrap your gun in a layer of superconducting tape. Magnetic fields cannot pass through a layer of superconductor, so the scanner wouldn’t see the gun’s field. The scanner would see the superconductor’s field, though. However, this can be countered by adding a layer of flexible magnetic strip, rather like that found on the back of a fridge magnet. The researchers showed that this combination of readily available materials does a reasonable job of cloaking a magnetic field.

Touching the void

OK, it’s still not quite a credible threat. The superconductor has to be kept at liquid-nitrogen temperatures and a cloud of nitrogen vapour coming out of your hand luggage might raise a few eyebrows. A simple thermal detector would certainly put paid to any gun-smuggling plans.

But the physicists aren’t beaten yet. While some have been content to bend light as it travels through space, Martin McCall of Imperial College London has played around with bending light as it travels though time.

The technique involves slowing down and speeding up light inside an optical fibre – something that physicists have learned to do with astonishing skill in the past few years. McCall now has a blueprint for a device that doesn’t just make things invisible; it makes it look like they never even happened. It only works on technologies with an optical fibre feed, such as a CCTV camera. Nevertheless, in principle, we now know how to create the illusion of a void in both space and time – a void that could plausibly be exploited to evade surveillance technologies. Of course, it’s ridiculous. But where these troublesome physicists are involved, nothing remains ridiculous for long.

Michael Brooks’s “Free Radicals: the Secret Anarchy of Science” is published by Profile Books (£12.99)

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 30 April 2012 issue of the New Statesman, The puppet master

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The moonwalkers: what it's like to belong to the world's most exclusive club

"The blue and the white and the brown just hung in the blackness of space."

It’s been almost 50 years since man first walked on the moon – and there were only a grand total of six missions.

From 1969 until 1972, as humanity reached out into space, these men – and they were all men – were at the forefront of scientific research and discovery.

But in 2017, the six survivors – now with a combined age of 505 – are the rare members of an exclusive club. The other six moonwalkers have already passed away.

Astronaut Buzz Aldrin was on Apollo 11, Charlie Duke was on Apollo 16 and Harrison "Jack" Schmitt was an Apollo 17 moonwalker. For the first time, at the Starmus festival in Trondheim, Norway, the three have come together to discuss their experience.

The three share “a special relationship, no question about it”, according to Duke. He tells me: “Our experiences are different but they’re the same in so many respects.”

Aldrin – unable to appear in person due to doctor’s orders – quips on camera from his home in Florida that President Dwight Eisenhower was advised that they should send a philosopher or maybe a poet up. His response, possibly apocryphal, came: “No, no - I want success."

As a result, it is up to these scientists to find the words to describe the off-Earth adventure which is the defining event of a moonwalker's life. 

A poetic description comes from Texan resident Duke. First and foremost a test pilot, his interest in space was piqued by the launch of Sputnik, the first artificial satellite, in 1957. He joined Nasa in 1966.

Now 81, Duke served as mission control support throughout many Apollo missions, most notably as the voice of Capsule Communicator when Neil Armstrong and Aldrin landed on the Moon in 1969.

He tells me: “Once we left Earth’s orbit, we turned our spaceship around and there was the whole Earth 40,000km away.

“The blue and the white and the brown just hung in the blackness of space. That contrast between the vivid blackness and the bright Earth – this jewel of Earth I like to call it - was right there.”

Aldrin started his career as a mechanical engineer, before joining up as a jet fighter in the US Air Force during the Korean War.

His gung-ho spirit and enthusiasm for space have not deserted him even at the age of 87 – he appears onscreen at the festival wearing a "Get your ass to Mars" T-shirt.

The most memorable experience for him came when he congratulated Neil Armstrong, the first of the team to walk on the moon (he died in 2012). But in the lunarscape, memories get confused – the men remember the moment differently.

“After the landing, I looked over at Neil, and we smiled. I remember patting him on the back and he remembers shaking hands. So here were two first-hand witnesses and we couldn’t agree on what actually happened when we got there.”

For Aldrin, the significance of the moonwalk was looking at the moon’s surface from close-up – the lunar soil, or regolith – and what happened when an astronaut's boot stepped onto it. 

“It was so remarkable, the way that it retained its exact form,” he marvels, 48 years on.

Aldrin's fascination with the moon's surface was shared by Schmitt, the 12th, and so far, last, man to walk on the Moon. A trained geologist, he was also the first scientist to do so.

In Schmitt's case, the rocky surface of the moon was enough to draw him into lunar research, which he still conducts at the age of 81.

“The commander told me as soon as I got out I had to look up and see the Earth," he recalls. "I said ‘Well, chief, you’ve seen one Earth, you’ve seen them all’."

In truth, having spent three days looking at the Earth from his craft, Schmitt’s priority was in looking down at the new surface under his feet.

After landing in a valley deeper than the Grand Canyon, his chief concern was just getting to work collecting samples in a lifesize laboratory.

While the moment on the moon may be the initiation into an elevated celebrity, it is followed quite literally a fall back to earth. 

In his post-Moon life, Duke found God.

“A lot of us have a letdown [afterwards]," he admits. Duke was 36 when he landed on the moon in April 1972. By December, the Apollo programme was over. "In January ’73, the thought occurred to me, ‘what am I going to do now?’"

Achieving his life's ambition before hitting middle age turned out not to be as satisfying as he expected. "Because you’d climbed the top, you got to the ultimate high when you were still a young man - and the drive that took you to the ultimate high was still there," he says. "That was a struggle."

In the years since, Duke has looked at his experience as a religious one. Yet he insists God wasn’t present for him when he touched down on the lunar body.

“The Moon flight was not a spiritual experience," he says. "I didn’t understand the wonder of God’s universe. I was enjoying the beauty and the excitement of this mission.”

The three men agree that Mars is the next step for the future of humanity, but there are safety and speed concerns.

“There is potential important work to be done in better physiological understanding of human exposure to long duration space flight which is going to happen whenever we go to Mars,” says Schmitt.

“Anything we do as human beings that’s productive and worthwhile carries risk, either physical of psychological. Radiation, physiological exposure to weightlessness for long durations, and the danger of landing on a distant planet where the atmosphere is not going to be much help - but you do accept the risk that it might end up as a one-way trip.”

But after all of that - the life, the death, the heartache - Duke says he would go back up there if he could.

“At my age now I wouldn’t volunteer to go to Mars - but I would volunteer for a round-trip to the Moon again.”

Starmus Festival runs in Trondheim until Friday June 23. For more information, visit Starmus.

Kirstie McCrum is a freelance journalist. Follow her @kirstiemccrum.

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