News from the UK today that new tokamak ST-40 has been turned on, so I thought I’d post a little explainer about how fusion works.
The editor thought Harry Potter was so last decade, so this Cosmos article got majorly changed. Thought the original wasn’t bad though…
Harry Potter’ invisibility cloak might just have been trumped by a French team, who aim to make entire buildings invisible. Scientists from the Institut Fresnel in Marseilles are teaming up with geo-engineering company Ménard for an experiment in the shape of a circle, two hundred metres across – enough to protect the whole of Hogwarts School (or more realistically a sensitive site such as a nuclear plant).
The team are not striving for invisibility to human eyes: instead of light waves they will divert the waves that travel through the surface of the earth during earthquakes and other seismic disturbances. As they reported in last month’s Physics Review Letters they have already succeeded with an area the size of Harry Potter’s Gryffindor common room.
“We managed to stop the propagation of the waves,” says the leader of the team, physicist Sebastien Guenneau. “This is the first proof of concept of a seismic metamaterial, a structure which can scatter and deflect wave trajectories. You can build on this knowledge to create an invisibility cloak which will actually protect a specific site from seismic waves.”
Metamaterials were first developed in the optics domain. They are substances comprised of an array of small elements, whose regular pattern leads to unusual behaviour on a large scale. Guenneau studied at Imperial College London with the pioneer of metamaterials, Sir John Pendry; Pendry shook the optics world in the early 2000s when he proposed an invisibility cloak based on metamaterials, and then, in collaboration with David Smith from Duke University, built such a device that operated at microwave wavelengths.
The strange effects that metamaterials have on waves rely on geometric structures that are smaller than the waves they are influencing. For Pendry’s centimeter-scale microwaves the patterns were millimetres in size, but for Guenneau’s team, dealing with earthquake wavelengths of around a metre and a half, the structures were 30cm wide boreholes, spaced roughly a metre apart.
However, unlike metamaterials based on pure, man-made substances, the earth is much less homogeneous.
“Soil is a different story,” says Guenneau. “Its properties are difficult to characterise, and depend on different things, such as the weather! It makes the mathematical models much more difficult.”
Overcoming more than just mathematical hurdles – other scientists initially ridiculed the theory – Guenneau fortuitously met geo-engineer at Ménard, Stephane Brûlé, who was open minded and influential enough to persuade his company to collaborate on the idea – albeit during the summer holiday period.
So it was that the team of twenty people studied the weather forecasts carefully and chose three sunny days in August 2012, to take the measurements at a site near Grenoble.
Using a seismic source vibrating the ground at 50 times a second they first measured the propagation of the waves in the undisturbed soil. Then after carefully drilling three rows of five metre deep holes, they repeated the experiment. Sure enough, as the model predicted, most of the energy was reflected by the hole pattern; behind the array the detectors only measured one fifth of the energy that had reached the detector before the holes were drilled.
“It’s interesting because these are the first experimental results on this topic,” says University of Sydney physicist, Professor Boris Kuhlmey, who studies electromagnetic metamaterials that function at the nanometer wavelengths of light. “It’s the very beginning of the field: the modelling is quite extensive, but the experiment is quite limited in scope. The structure they have explored will only work over a narrow band of frequencies, but if your aim is to stop an earthquake you don’t get to choose the frequency.”
However Kuhlmey says Guenneau’s mathematical models offer the possibility of a phenomenon known as a zero stop band, which can cut out a wide range of earthquake waves. “These exist in electromagnetic metamaterials – the paper suggests that for seismic waves they are possible too. That would be really key to get it to work well. Maybe it’s possible, on the scale of a city, to diminish the impact of an earthquake considerably.”
Guenneau’s next experiment will certainly push back the boundaries. The team will inflict earthquakes measuring six on the Richter scale, with frequencies of between 2 and 12 vibrations per second on their test site, protected by a ring of boreholes 200 metres in diameter.
“It would be a dream for me to see this done for real one day, not just tests,” muses Guenneau. But he is not precious about his idea. “I am sure that the civil engineers will come up with better ways to make it work, I don’t have the expertise,” he says.
In the meantime he is already turning his considerable skills to other problems, such as tsunami control. “Imagine some columns of wood, 200 m from the sea shore, arranged in a similar fashion to the bore holes in the seismic experiments. The effect will be that you deflect or guide the tsunami to a nonsensitive coastal area.”
“Also, I’d like to do some work in biology…” he throws in.
Originally published in Cosmos Magazine 28/4/14
The best part of my job as a science writer is when scientists explain their work to me. I like it when they go into far too much detail, (which I then have to leave out of the story).
But I don’t think I am normal.
Throughout my physics studies, I loved to tutor students, take tours though the lab, which led me into a career in Science Communication. My first real job in Sci Comm was at University of Sydney, working with a lot of teenagers.
But I found not all the teenagers were as interested in physics as I was. (Who would have thought?) So I started explaining harder, with more creative analogies and more engaging presentations.
Which helped a little.
But I still remember a presentation at a school on the semi-rural outskirts of Sydney, when there were a posse of kids at the front lapping up my superconductivity and projectile motion demos. But three-quarters of the year eights were bored out of their brains. The back row were running in and out of the theatre playing chasies, despite their teacher’s best efforts. How could they not care about a levitating magnet at -196 degrees?
Around the same time I’d been reading Bill Bryson’s Short History of Nearly Everything. I actually usually prefer novels to non-fiction, but Bryson’s non-fiction completely sucked me in with its stories of how we learned about the world around us. Surprisingly it was his descriptions of the humans who made the discoveries that captivated me. No lecturer had ever told me Newton was mad (possibly mercury poisoning). No exam had ever asked whether Hubble was a compulsive liar.
Yet these characters were making this book such a page turner, even though I knew a fair percentage of the science facts he was relating.
The pieces started to fall into place when I went to my first ever non-physics conference – the Australian Science Communicators Conference. Here were people studying the very issues that were troubling me.
It was a lecture from a biophysicist turned social scientist that really rocked the boat. In a 15 minute talk Professor Joan Leach, then at University of Queensland, suggested there were other ways of presenting science to audiences, than just a series of facts in a logical order. Exploratory learning. Historical re-enactments. Human stories.
I couldn’t wait to get back to work and try these ideas out. Soon I was trying out things like a high school workshop in which the clues to a code were embedded in 15 experiments in the lab – inspired by the da Vinci code. My student feedback started climbing.
(Not all my experiments were successful – my tip, don’t ask shy, geeky teenagers to do dramatic re-enactments of famous experiments in front of their peers. Far too scary!)
There was one thing I still couldn’t come at. I had the good fortune to visit Princeton’s Institute for Materials, where they had an exhibition of science art. And I also saw Quark Park, a science sculpture garden. I’ll admit, some of it looked quite nice. Some of the sculptures were kinda cute, but what was I supposed to learn from it? It didn’t demonstrate deep scientific principles nearly as well as a graph or an equation did.
While I muttered about uselessness on the train home, worlds were clashing at a much grander scale.
The world’s climate was changing. Proving that it was actually possible to herd cats, researchers from all kinds of disciplines and countries came together to form the Intergovernmental Panel on Climate Change, and presented a united and terrifying view of the effect humans were having on the whole planet.
People began to listen. Al Gore took the bull by the horns and people began to think about how to change. But then it all went wrong.
People started popping up and disagreeing with the research. The scientists were gobsmacked. They’d managed to come to a consensus, surely no one would believe people with no scientific credentials, sponsored by the fossil fuel industry?
But sure enough, public opinion turned around. Seeds of distrust were sown, the truth became inconvenient, and no matter how hard scientists explained their research, the number of climate change deniers grew and grew.
The arc continues today, with the election of Donald Trump. It’s now a post-fact world. It’s so clear that the adversarial approach of presenting facts to back up your argument doesn’t convert your opposition. In fact, it entrenches their views (after all, who likes to be proven wrong?)
Again, a social scientist, engineer-turned-science communication researcher, Professor Will Rivkin, then at UNSW, rattled my cage, with a 5 minute talk about trust. About how people need to know not only that someone is competent, but also has their best interests at heart before they trust them.
A wonderful blog post in Scientific American by Bora Zivkovic went into it more deeply. In short, the things that we humans have traditionally used to judge people, to form our first impressions, are very subjective. We decide whether someone is a danger to us from cultural clues: whether they look, speak and behave like us. Do they share our emotions, our vulnerabilities, our humanity?
But of course good science goes out of its way to remove all those cultural influences. As objective as possible.
And when science is presented in that way, people don’t naturally trust it. It seems robotic. Who’s saying this? Do they have my best interests at heart? I don’t know because it’s all written in the passive voice!
So when scientists ask me how to communicate I tell them to use their emotions. Sure, facts are facts, but your reaction to them is your own. I say, “the evidence shows a clear rise in global temperatures, and that terrifies me!”
People without a scientific background will connect with that emotion, it tells a much more compelling story for them than the hockey stick graph that terrifies me.
But still people will turn away if they don’t want to hear. They didn’t come here to learn something, especially not something uncomfortable, threatening, and with no easy answer.
It clicked for me as I listened to a marketing pitch from the editor of the Australian science magazine Cosmos, trying to persuade my University to buy advertising. He talked about the space his readers were in – not a busy newsy space like New Scientist readers, but a broader, slower more absorbed space.
That weekend, as I sat listening to my economist father-in-law explaining the intricacies of the free market’s spread into former eastern bloc countries, I thought, I’m not in this space. This is a BBQ; for once I didn’t come here to learn anything.
Suddenly I got the art park. It was hard for me to swallow, but maybe people didn’t always want science explained to them. They just wanted to look at something nice. Engage with something on an aesthetic level, without battling challenging concepts or non-intuitive quantum contradictions.
My journalism teacher had told me, entertain first, then inform. Because if you don’t entertain, no one will read it and so there’ll be no informing at all.
So it was in the art park. People would walk away with a good feeling about science. An emotional connection that helped them to not feel alienated. To trust science, even.
It didn’t actually matter whether they could now pass a test about Schrodinger’s equation, and the shapes of S, P and D orbitals. If they decided to find out more, Professor Google would help them, when they were in a learning mood.
So I started incorporating songs into my science presentations. I can’t help myself but explain stuff first – but then I take a song everyone knows, change the words to be about the science I’ve been discussing and get the audience to sing along. The Beatles’ Hey Jude becomes Hey Plute.
Australian audiences are a little unsure about this, but after a beer or two they usually get into it, and end up loving it. There’s something magical about singing together (plus it breaks up the quietly-listening audience paradigm, but that’s a whole other discussion.)
It feels almost underhand, like Hitler manipulating crowds with stirring marches. But that’s what science is up against. Well-orchestrated marketing campaigns use all the arts and social sciences to woo their audience at an emotional level, and that will trump facts every time (pun intended).
I came across a little story from my Anglican childhood recently, about a man at the pearly gates, looking back at his life as a walk along a beach. Noticing a second pair of footsteps, the man asks Jesus whose they are. Jesus says they are his, he walked beside him his whole life. But the man sees the dark parts of his life, and only one set of footsteps – why did you abandon me? No, I didn’t Jesus says; I carried you.
Now, that didn’t happen. Someone made it up. It’s a lovely story, and it made a big impact on me as an eight-year old, but it’s just not real.
Can science ever prevail when made up stories are so powerful? Time will tell. But in the meantime I decided to make some stuff up too. I wrote a science fairytale, about a prince searching for love, who is courted by scientist would-be princesses. There’s blackbody radiation, mars exploration, genetic modification, solar spectra, Rayleigh scattering, love and a happy ever after.
It doesn’t matter that it never happened – human brains are hard-wired to remember stories. And if people want to find out more about why photosynthesis is so terribly inefficient that there is no way an intelligent designer would have made it that way, the internet is there.
This is my challenge to the scientific community. Don’t be afraid to be a human, a scientist with emotions. Of course, keep your research as objective as possible, but when you’re out of the ivory tower, embrace the arts. Give them a science flavour, tell your own story as a human.
Just don’t explain it.
The author would like to acknowledge Rebecca Blackburn and David Harris.
Dr Ayana Arce is part of a team that does experiments at the Large Hadron Collider, looking for evidence for the fifth dimension.
Biologist Dr Chris Fulton and Masters student Mae Noble sat around the campfire as the sun rose, looking at their frozen wetsuits.
Soon they would have to struggle into them ready for a day of snorkelling in freezing high country streams, looking for glimpses of the Murray Crayfish, the world’s second largest.
It had been a long hike the day before up into the high country west of Canberra, laden with underwater cameras and snorkelling gear. It had a confronting end as they reached their destination, the Goobarragandra River.
Dr Fulton had described to the American student the shady trees hanging over the idyllic stream of clear water gurgling over boulders he visited six years earlier.
But when they arrived, the trees had gone and only a muddy creek remained.
“It was hard to believe it was the same stream, it was pretty brutal,” says Fulton, GradCertHE ’09, a biologist from the ANU Research School of Biology.
Huge floods in 2012 had devastated the Goobarragandra, eroding the banks and choking it with silt.
As the pair began searching for the iconic crayfish with its distinctive white claws, their fears were confirmed. The population had plunged by 95 per cent.
Silicon holograms harness the full visible spectrum to bring holographic projections one step closer
We can’t yet send holographic videos to Obi-Wan Kenobi on our droid, but A*STAR researchers have got us a little bit closer by creating holograms from an array of silicon structures that work throughout the visible spectrum1.
Many recent advances in hologram technology use reflected light to form an image; however the hologram made by Dong Zhaogang and Joel Yang from the A*STAR Institute of Materials Research and Engineering uses transmitted light. This means the image is not muddled up with the light source.
The team demonstrated the hologram of three flat images at wavelengths ranging from blue (480 nanometers) to red (680 nanometers). The images appeared in planes 50 microns apart for red and higher spacings for shorter wavelengths.
“In principle, it can be tuned to any wavelength,” says Yang.
Holograms can record three-dimensional images, which mean they can store large amounts of information in increasingly thin layers.
Recently, holograms that are mere hundredths of the thickness of a human hair have been made from metal deposited onto materials such as silicon. The holograms are created by nanoscale patterns of metal that generate electromagnetic waves that travel at the metal–silicon interface; a field called plasmonics.
Silicon holograms are slightly thicker than the metal-based ones, but have the advantage of being broadband. Plasmonic holograms only operate in the red wavelengths because they undergo strong absorption at blue wavelengths.
A disadvantage of the silicon holograms is their poor efficiency at only three per cent; however Dong estimates this could easily be tripled.
“The losses can be lowered by optimizing the growth method to grow polycrystalline silicon instead of amorphous silicon,” he says.
The hologram is an array of tiny silicon skyscrapers, 370 nanometers tall with footprints 190 nanometers by 100 nanometers. Unlike a city grid, however, the tiny towers are not laid out in neat squares but at varying angles.
The hologram operates with circularly polarized light, and the information is encoded on to the light beam by the varied angles of the skyscrapers. These alter the phase of the transmitted light through the ‘Pancharatnam–Berry effect’.
“What’s interesting about this hologram is that it controls only the phase of the light by varying the orientation of the silicon nanostructures. The amplitude is the same everywhere; in principle you can get a lot of light transmitted,” says Yang.
The A*STAR researchers focused on nanofabrication and measurements and collaborated with Cheng-Wei Qiu from National University of Singapore, whose team specializes in hologram design.
- Huang, K., Dong, Z., Mei, S., Zhang, L., Liu, Y. et al. Silicon multi-meta-holograms for the broadband visible light. Laser & Photonics Reviews 10, 500–509 (2016). | Article
Original on A*STAR journal website, published by Nature Group.
I wrote this as a writing test in a job interview for CSIRO. Thought it was OK – but i didn’t get the job….
Have you ever wondered what would happen if a shooting star collided with a star? Well, scientists at CSIRO think they have discovered just that! Unfortunately the collision is too far away to see, but the scientists have discovered that Star PSR J0738-4042 is bombarded – regularly!
Shooting stars are actually pieces of spacerock that burn up as they fall into our atmosphere. Spacerocks are falling into PSR J0738-4042 as a result of it exploding in the past, flinging out debris that is now falling back in on itself.
In the explosion the star became a pulsar that shoots out radio waves as it spins, at nearly three turns per second. The falling debris gets zapped by the radio waves, turning it into plasma, which then affects the star’s regular pulses. By measuring changes in the pulses the scientists calculated the mass of one of the rocks at around a billion tonnes!
For Patricia Brennan, duck penis researcher from University of Massachusetts..
Give thanks for the birth of Duck minor
Mother duck has a corkscrew vagina
But daddy’s erection
curls in the other direction
Proof God’s no intelligent designer
Duck love making’s no simple deed
what’s more god has deceed
that the knob of this stud
will drop off in the mud
as soon as he’s planted his seed
If you think this seems a sad song
the drake will regrow his dong
this new percy I’ve heard
measures a third of the bird
a behemoth that’s 8 inches long!
Things then get wronger and wronger
Sir Drake scares his mates with his donger
If he thinks he’s the king
it shows up in his thing
which grows to be 20 % longer
So you think your love life’s out of luck
Be thankful you are not a duck.
your bits stay attached
and your organs are matched
when you’re both in the mood for a ….. cuddle.
Quantum physics is all about the simplest things in the universe. Matter – electrons and quarks (which make up neutrons and protons), and interactions – photons, forces etc.
The difference between the two is a simple rotation. It’s secret quantum mechanics knowledge, says head of ANU Dept of Quantum Physics, Professor Craig Savage.
Here he is proving it:
Filmed at Physics in the Pub ACT, 2016, August 17 at Smiths Alternative Bookshop
It’s a peaceful starry night, but Pete Kuzma has found the remains of a grisly murder in the sky – a dismembered dwarf. galaxy.
Part of the Physics in the Pub 2016 with Australian Institute of Physics ACT branch, supported by a National Science Week seed grant.
Filming by Jon and Liam from Crus Productions.